Re: [PATCH v4 2/3] cxlflash: Superpipe support

Michael Neuling
2015-08-11T05:23:19Z

Some comments inline

On Mon, 2015-08-10 at 12:09 -0500, Matthew R. Ochs wrote:
> Add superpipe supporting infrastructure to device driver for the IBM CXL
> Flash adapter. This patch allows userspace applications to take advantage
> of the accelerated I/O features that this adapter provides and bypass the
> traditional filesystem stack.
>
> Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
> Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
> ---
> Documentation/ioctl/ioctl-number.txt | 1 +
> Documentation/powerpc/cxlflash.txt | 297 +++++
> drivers/scsi/cxlflash/Makefile | 2 +-
> drivers/scsi/cxlflash/common.h | 19 +
> drivers/scsi/cxlflash/main.c | 21 +-
> drivers/scsi/cxlflash/superpipe.c | 2206 ++++++++++++++++++++++++++++++++++
> drivers/scsi/cxlflash/superpipe.h | 127 ++
> include/uapi/scsi/Kbuild | 1 +
> include/uapi/scsi/cxlflash_ioctl.h | 139 +++
> 9 files changed, 2810 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/powerpc/cxlflash.txt
> create mode 100644 drivers/scsi/cxlflash/superpipe.c
> create mode 100644 drivers/scsi/cxlflash/superpipe.h
> create mode 100644 include/uapi/scsi/cxlflash_ioctl.h
>
> diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
> index fdd35bf..67273e1 100644
> --- a/Documentation/ioctl/ioctl-number.txt
> +++ b/Documentation/ioctl/ioctl-number.txt
> @@ -315,6 +315,7 @@ Code Seq#(hex) Include File Comments
> 0xC0 00-0F linux/usb/iowarrior.h
> 0xC9 00-0F uapi/cxl-memcpy.h Reserved for non-upstream prototype

This above doesn't exist upstream. Make sure your patch applies to a
clean tree.

> 0xCA 00-0F uapi/misc/cxl.h
> +0xCA 80-8F uapi/scsi/cxlflash_ioctl.h
> 0xCB 00-1F CBM serial IEC bus in development:
> <mailto:michael.klein@puffin.lb.shuttle.de>
> 0xCD 01 linux/reiserfs_fs.h
> diff --git a/Documentation/powerpc/cxlflash.txt b/Documentation/powerpc/cxlflash.txt
> new file mode 100644
> index 0000000..4a59f1a
> --- /dev/null
> +++ b/Documentation/powerpc/cxlflash.txt
> @@ -0,0 +1,297 @@
> +Introduction
> +============
> +
> + The IBM Power architecture provides support for CAPI (Coherent
> + Accelerator Power Interface), which is available to certain PCIe slots
> + on Power 8 systems. CAPI can be thought of as a special tunneling
> + protocol through PCIe that allow PCIe adapters to look like special
> + purpose co-processors which can read or write an application's
> + memory and generate page faults. As a result, the host interface to
> + an adapter running in CAPI mode does not require the data buffers to
> + be mapped to the device's memory (IOMMU bypass) nor does it require
> + memory to be pinned.
> +
> + On Linux, Coherent Accelerator (CXL) kernel services present CAPI
> + devices as a PCI device by implementing a virtual PCI host bridge.
> + This abstraction simplifies the infrastructure and programming
> + model, allowing for drivers to look similar to other native PCI
> + device drivers.
> +
> + CXL provides a mechanism by which user space applications can
> + directly talk to a device (network or storage) bypassing the typical
> + kernel/device driver stack. The CXL Flash Adapter Driver enables a
> + user space application direct access to Flash storage.
> +
> + The CXL Flash Adapter Driver is a kernel module that sits in the
> + SCSI stack as a low level device driver (below the SCSI disk and
> + protocol drivers) for the IBM CXL Flash Adapter. This driver is
> + responsible for the initialization of the adapter, setting up the
> + special path for user space access, and performing error recovery. It
> + communicates directly the Flash Accelerator Functional Unit (AFU)
> + as described in Documentation/powerpc/cxl.txt.
> +
> + The cxlflash driver supports two, mutually exclusive, modes of
> + operation at the device (LUN) level:
> +
> + - Any flash device (LUN) can be configured to be accessed as a
> + regular disk device (i.e.: /dev/sdc). This is the default mode.
> +
> + - Any flash device (LUN) can be configured to be accessed from
> + user space with a special block library. This mode further
> + specifies the means of accessing the device and provides for
> + either raw access to the entire LUN (referred to as direct
> + or physical LUN access) or access to a kernel/AFU-mediated
> + partition of the LUN (referred to as virtual LUN access). The
> + segmentation of a disk device into virtual LUNs is assisted
> + by special translation services provided by the Flash AFU.
> +
> +Overview
> +========
> +
> + The Coherent Accelerator Interface Architecture (CAIA) introduces a
> + concept of a master context. A master typically has special privileges
> + granted to it by the kernel or hypervisor allowing it to perform AFU
> + wide management and control. The master may or may not be involved
> + directly in each user I/O, but at the minimum is involved in the
> + initial setup before the user application is allowed to send requests
> + directly to the AFU.
> +
> + The CXL Flash Adapter Driver establishes a master context with the
> + AFU. It uses memory mapped I/O (MMIO) for this control and setup. The
> + Adapter Problem Space Memory Map looks like this:
> +
> + +-------------------------------+
> + | 512 * 64 KB User MMIO |
> + | (per context) |
> + | User Accessible |
> + +-------------------------------+
> + | 512 * 128 B per context |
> + | Provisioning and Control |
> + | Trusted Process accessible |
> + +-------------------------------+
> + | 64 KB Global |
> + | Trusted Process accessible |
> + +-------------------------------+
> +
> + This driver configures itself into the SCSI software stack as an
> + adapter driver. The driver is the only entity that is considered a
> + Trusted Process to program the Provisioning and Control and Global
> + areas in the MMIO Space shown above. The master context driver
> + discovers all LUNs attached to the CXL Flash adapter and instantiates
> + scsi block devices (/dev/sdb, /dev/sdc etc.) for each unique LUN
> + seen from each path.
> +
> + Once these scsi block devices are instantiated, an application
> + written to a specification provided by the block library may get
> + access to the Flash from user space (without requiring a system call).
> +
> + This master context driver also provides a series of ioctls for this
> + block library to enable this user space access. The driver supports
> + two modes for accessing the block device.
> +
> + The first mode is called a virtual mode. In this mode a single scsi
> + block device (/dev/sdb) may be carved up into any number of distinct
> + virtual LUNs. The virtual LUNs may be resized as long as the sum of
> + the sizes of all the virtual LUNs, along with the meta-data associated
> + with it does not exceed the physical capacity.
> +
> + The second mode is called the physical mode. In this mode a single
> + block device (/dev/sdb) may be opened directly by the block library
> + and the entire space for the LUN is available to the application.
> +
> + Only the physical mode provides persistence of the data. i.e. The
> + data written to the block device will survive application exit and
> + restart and also reboot. The virtual LUNs do not persist (i.e. do
> + not survive after the application terminates or the system reboots).
> +
> +
> +Block library API
> +=================
> +
> + Applications intending to get access to the CXL Flash from user
> + space should use the block library, as it abstracts the details of
> + interfacing directly with the cxlflash driver that are necessary for
> + performing administrative actions (i.e.: setup, tear down, resize).
> + The block library can be thought of as a 'user' of services,
> + implemented as IOCTLs, that are provided by the cxlflash driver
> + specifically for devices (LUNs) operating in user space access
> + mode. While it is not a requirement that applications understand
> + the interface between the block library and the cxlflash driver,
> + a high-level overview of each supported service (IOCTL) is provided
> + below.
> +
> + The block library can be found on GitHub:
> + http://www.github.com/mikehollinger/ibmcapikv
> +
> +
> +CXL Flash Driver IOCTLs
> +=======================
> +
> + Users, such as the block library, that wish to interface with a flash
> + device (LUN) via user space access need to use the services provided
> + by the cxlflash driver. As these services are implemented as ioctls,
> + a file descriptor handle must first be obtained in order to establish
> + the communication channel between a user and the kernel. This file
> + descriptor is obtained by opening the device special file associated
> + with the scsi disk device (/dev/sdb) that was created during LUN
> + discovery. As per the location of the cxlflash driver within the
> + SCSI protocol stack, this open is actually not seen by the cxlflash
> + driver. Upon successful open, the user receives a file descriptor
> + (herein referred to as fd1) that should be used for issuing the
> + subsequent ioctls listed below.
> +
> + The structure definitions for these IOCTLs are available in:
> + uapi/scsi/cxlflash_ioctl.h
> +
> +DK_CXLFLASH_ATTACH
> +------------------
> +
> + This ioctl obtains, initializes, and starts a context using the CXL
> + kernel services. These services specify a context id (u16) by which
> + to uniquely identify the context and its allocated resources. The
> + services additionally provide a second file descriptor (herein
> + referred to as fd2) that is used by the block library to initiate
> + memory mapped I/O (via mmap()) to the CXL flash device and poll for
> + completion events. This file descriptor is intentionally installed by
> + this driver and not the CXL kernel services to allow for intermediary
> + notification and access in the event of a non-user-initiated close(),
> + such as a killed process. This design point is described in further
> + detail in the description for the DK_CXLFLASH_DETACH ioctl.
> +
> + There are a few important aspects regarding the "tokens" (context id
> + and fd2) that are provided back to the user:
> +
> + - These tokens are only valid for the process under which they
> + were created. The child of a forked process cannot continue
> + to use the context id or file descriptor created by its parent
> + (see DK_CXLFLASH_CLONE for further details).
> +
> + - These tokens are only valid for the lifetime of the context and
> + the process under which they were created. Once either is
> + destroyed, the tokens are to be considered stale and subsequent
> + usage will result in errors.
> +
> + - When a context is no longer needed, the user shall detach from
> + the context via the DK_CXLFLASH_DETACH ioctl.
> +
> + - A close on fd2 will invalidate the tokens. This operation is not
> + required by the user.
> +
> +DK_CXLFLASH_USER_DIRECT
> +-----------------------
> + This ioctl is responsible for transitioning the LUN to direct
> + (physical) mode access and configuring the AFU for direct access from
> + user space on a per-context basis. Additionally, the block size and
> + last logical block address (LBA) are returned to the user.
> +
> + As mentioned previously, when operating in user space access mode,
> + LUNs may be accessed in whole or in part. Only one mode is allowed
> + at a time and if one mode is active (outstanding references exist),
> + requests to use the LUN in a different mode are denied.
> +
> + The AFU is configured for direct access from user space by adding an
> + entry to the AFU's resource handle table. The index of the entry is
> + treated as a resource handle that is returned to the user. The user
> + is then able to use the handle to reference the LUN during I/O.
> +
> +DK_CXLFLASH_USER_VIRTUAL
> +------------------------
> + This ioctl is responsible for transitioning the LUN to virtual mode
> + of access and configuring the AFU for virtual access from user space
> + on a per-context basis. Additionally, the block size and last logical
> + block address (LBA) are returned to the user.
> +
> + As mentioned previously, when operating in user space access mode,
> + LUNs may be accessed in whole or in part. Only one mode is allowed
> + at a time and if one mode is active (outstanding references exist),
> + requests to use the LUN in a different mode are denied.
> +
> + The AFU is configured for virtual access from user space by adding
> + an entry to the AFU's resource handle table. The index of the entry
> + is treated as a resource handle that is returned to the user. The
> + user is then able to use the handle to reference the LUN during I/O.
> +
> + By default, the virtual LUN is created with a size of 0. The user
> + would need to use the DK_CXLFLASH_VLUN_RESIZE ioctl to adjust the grow
> + the virtual LUN to a desired size. To avoid having to perform this
> + resize for the initial creation of the virtual LUN, the user has the
> + option of specifying a size as part of the DK_CXLFLASH_USER_VIRTUAL
> + ioctl, such that when success is returned to the user, the
> + resource handle that is provided is already referencing provisioned
> + storage. This is reflected by the last LBA being a non-zero value.

This should be in the vlun patch.

> +DK_CXLFLASH_VLUN_RESIZE
> +-----------------------
> + This ioctl is responsible for resizing a previously created virtual
> + LUN and will fail if invoked upon a LUN that is not in virtual
> + mode. Upon success, an updated last LBA is returned to the user
> + indicating the new size of the virtual LUN associated with the
> + resource handle.
> +
> + The partitioning of virtual LUNs is jointly mediated by the cxlflash
> + driver and the AFU. An allocation table is kept for each LUN that is
> + operating in the virtual mode and used to program a LUN translation
> + table that the AFU references when provided with a resource handle.

All this vlun discussion would be in the next patch not this superpipe patch.

> +DK_CXLFLASH_RELEASE
> +-------------------
> + This ioctl is responsible for releasing a previously obtained
> + reference to either a physical or virtual LUN. This can be
> + thought of as the inverse of the DK_CXLFLASH_USER_DIRECT or
> + DK_CXLFLASH_USER_VIRTUAL ioctls. Upon success, the resource handle
> + is no longer valid and the entry in the resource handle table is
> + made available to be used again.
> +
> + As part of the release process for virtual LUNs, the virtual LUN
> + is first resized to 0 to clear out and free the translation tables
> + associated with the virtual LUN reference.

Looks like file_ops release calls these functions anyway. So why do we need
this?

> +DK_CXLFLASH_DETACH
> +------------------
> + This ioctl is responsible for unregistering a context with the
> + cxlflash driver and release outstanding resources that were
> + not explicitly released via the DK_CXLFLASH_RELEASE ioctl. Upon
> + success, all "tokens" which had been provided to the user from the
> + DK_CXLFLASH_ATTACH onward are no longer valid.

Why split this between detach and release? Can you reused a released context?

> +DK_CXLFLASH_CLONE
> +-----------------
> + This ioctl is responsible for cloning a previously created
> + context to a more recently created context. It exists solely to
> + support maintaining user space access to storage after a process
> + forks. Upon success, the child process (which invoked the ioctl)
> + will have access to the same LUNs via the same resource handle(s)
> + and fd2 as the parent, but under a different context.
> +
> + Context sharing across processes is not supported with CXL and
> + therefore each fork must be met with establishing a new context
> + for the child process. This ioctl simplifies the state management
> + and playback required by a user in such a scenario. When a process
> + forks, child process can clone the parents context by first creating
> + a context (via DK_CXLFLASH_ATTACH) and then using this ioctl to
> + perform the clone from the parent to the child.
> +
> + The clone itself is fairly simple. The resource handle and lun
> + translation tables are copied from the parent context to the child's
> + and then synced with the AFU.

This should be in the vlun patch.

Also, should be called DK_CXLFLASH_VLUN_CLONE to be consisten with VLUN_RESIZE

> +
> +DK_CXLFLASH_VERIFY
> +------------------
> + This ioctl is used to detect various changes such as the capacity of
> + the disk changing, the number of LUNs visible changing, etc. In cases
> + where the changes affect the application (such as a LUN resize), the
> + cxlflash driver will report the changed state to the application.
>

This needs a broader description. Verify exactly what?

> +DK_CXLFLASH_RECOVER_AFU
> +-----------------------
> + This ioctl is used to drive recovery (if such an action is warranted)
> + of a specified user context. Any state associated with the user context
> + is re-established upon successful recovery.

Why would I call this? What scenario?

> +
> +DK_CXLFLASH_MANAGE_LUN
> +----------------------
> + This ioctl is used to switch a LUN from a mode where it is available
> + for file-system access (legacy), to a mode where it is set aside for
> + exclusive user space access (superpipe). In case a LUN is visible
> + across multiple ports and adapters, this ioctl is used to uniquely
> + identify each LUN by its World Wide Node Name (WWNN).

Should this be called something specific? DK_CXLFLASH_SUPERPIPE_MODE?

> diff --git a/drivers/scsi/cxlflash/Makefile b/drivers/scsi/cxlflash/Makefile
> index dc95e20..3de309c 100644
> --- a/drivers/scsi/cxlflash/Makefile
> +++ b/drivers/scsi/cxlflash/Makefile
> @@ -1,2 +1,2 @@
> obj-$(CONFIG_CXLFLASH) += cxlflash.o
> -cxlflash-y += main.o
> +cxlflash-y += main.o superpipe.o
> diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
> index 7e663f4..a890a9a 100644
> --- a/drivers/scsi/cxlflash/common.h
> +++ b/drivers/scsi/cxlflash/common.h
> @@ -107,6 +107,18 @@ struct cxlflash_cfg {
> struct pci_pool *cxlflash_cmd_pool;
> struct pci_dev *parent_dev;
>
> + atomic_t recovery_threads;
> + struct mutex ctx_recovery_mutex;
> + struct mutex ctx_tbl_list_mutex;
> + struct ctx_info *ctx_tbl[MAX_CONTEXT];

MAX_CONTEXT=512. This is pretty big!

> + struct list_head ctx_err_recovery; /* contexts w/ recovery pending */
> + struct file_operations cxl_fops;
> +
> + atomic_t num_user_contexts;
> +
> + struct list_head lluns; /* list of llun_info structs */
> + spinlock_t slock;
> +
> wait_queue_head_t tmf_waitq;
> bool tmf_active;
> wait_queue_head_t limbo_waitq;
> @@ -182,5 +194,12 @@ int cxlflash_afu_reset(struct cxlflash_cfg *);
> struct afu_cmd *cxlflash_cmd_checkout(struct afu *);
> void cxlflash_cmd_checkin(struct afu_cmd *);
> int cxlflash_afu_sync(struct afu *, ctx_hndl_t, res_hndl_t, u8);
> +void cxlflash_list_init(void);
> +void cxlflash_list_terminate(void);
> +int cxlflash_ioctl(struct scsi_device *, int, void __user *);
> +void cxlflash_stop_term_user_contexts(struct cxlflash_cfg *);
> +int cxlflash_mark_contexts_error(struct cxlflash_cfg *);
> +void cxlflash_term_luns(struct cxlflash_cfg *);
> +
> #endif /* ifndef _CXLFLASH_COMMON_H */
>
> diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
> index 18359d4..eb1bdd7 100644
> --- a/drivers/scsi/cxlflash/main.c
> +++ b/drivers/scsi/cxlflash/main.c
> @@ -519,7 +519,7 @@ static int cxlflash_eh_host_reset_handler(struct scsi_cmnd *scp)
> case STATE_NORMAL:
> cfg->state = STATE_LIMBO;
> scsi_block_requests(cfg->host);
> -
> + cxlflash_mark_contexts_error(cfg);
> rcr = cxlflash_afu_reset(cfg);
> if (!rcr)
> rc = FAILED;
> @@ -723,6 +723,7 @@ static struct scsi_host_template driver_template = {
> .module = THIS_MODULE,
> .name = CXLFLASH_ADAPTER_NAME,
> .info = cxlflash_driver_info,
> + .ioctl = cxlflash_ioctl,
> .proc_name = CXLFLASH_NAME,
> .queuecommand = cxlflash_queuecommand,
> .eh_device_reset_handler = cxlflash_eh_device_reset_handler,
> @@ -870,9 +871,11 @@ static void cxlflash_remove(struct pci_dev *pdev)
> spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);
>
> cfg->state = STATE_FAILTERM;
> + cxlflash_stop_term_user_contexts(cfg);
>
> switch (cfg->init_state) {
> case INIT_STATE_SCSI:
> + cxlflash_term_luns(cfg);
> scsi_remove_host(cfg->host);
> scsi_host_put(cfg->host);
> /* Fall through */
> @@ -2272,6 +2275,11 @@ static int cxlflash_probe(struct pci_dev *pdev,
> INIT_WORK(&cfg->work_q, cxlflash_worker_thread);
> cfg->lr_state = LINK_RESET_INVALID;
> cfg->lr_port = -1;
> + mutex_init(&cfg->ctx_tbl_list_mutex);
> + mutex_init(&cfg->ctx_recovery_mutex);
> + spin_lock_init(&cfg->slock);
> + INIT_LIST_HEAD(&cfg->ctx_err_recovery);
> + INIT_LIST_HEAD(&cfg->lluns);
>
> pci_set_drvdata(pdev, cfg);
>
> @@ -2333,7 +2341,9 @@ out_remove:
> static pci_ers_result_t cxlflash_pci_error_detected(struct pci_dev *pdev,
> pci_channel_state_t state)
> {
> + int rc = 0;
> struct cxlflash_cfg *cfg = pci_get_drvdata(pdev);
> + struct device *dev = &cfg->dev->dev;
>
> pr_debug("%s: pdev=%p state=%u\n", __func__, pdev, state);
>
> @@ -2343,7 +2353,10 @@ static pci_ers_result_t cxlflash_pci_error_detected(struct pci_dev *pdev,
>
> /* Turn off legacy I/O */
> scsi_block_requests(cfg->host);
> -
> + rc = cxlflash_mark_contexts_error(cfg);
> + if (unlikely(rc))
> + dev_err(dev, "%s: Failed to mark user contexts!(%d)\n",
> + __func__, rc);
> term_mc(cfg, UNDO_START);
> stop_afu(cfg);
>
> @@ -2427,6 +2440,8 @@ static int __init init_cxlflash(void)
> pr_info("%s: IBM Power CXL Flash Adapter: %s\n",
> __func__, CXLFLASH_DRIVER_DATE);
>
> + cxlflash_list_init();
> +
> return pci_register_driver(&cxlflash_driver);
> }
>
> @@ -2435,6 +2450,8 @@ static int __init init_cxlflash(void)
> */
> static void __exit exit_cxlflash(void)
> {
> + cxlflash_list_terminate();
> +
> pci_unregister_driver(&cxlflash_driver);
> }
>
> diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
> new file mode 100644
> index 0000000..802f1f5
> --- /dev/null
> +++ b/drivers/scsi/cxlflash/superpipe.c
> @@ -0,0 +1,2206 @@
> +/*
> + * CXL Flash Device Driver
> + *
> + * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
> + * Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
> + *
> + * Copyright (C) 2015 IBM Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/file.h>
> +#include <linux/moduleparam.h>
> +#include <linux/syscalls.h>
> +#include <misc/cxl.h>
> +#include <asm/unaligned.h>
> +
> +#include <scsi/scsi.h>
> +#include <scsi/scsi_host.h>
> +#include <scsi/scsi_cmnd.h>
> +#include <scsi/scsi_eh.h>
> +#include <uapi/scsi/cxlflash_ioctl.h>
> +
> +#include "sislite.h"
> +#include "common.h"
> +#include "superpipe.h"
> +
> +static struct cxlflash_global global;
> +
> +/**
> + * marshal_det_to_rele() - translate detach to release structure
> + * @detach: Destination structure for the translate/copy.
> + * @rele: Source structure from which to translate/copy.
> + */
> +static void marshal_det_to_rele(struct dk_cxlflash_detach *detach,
> + struct dk_cxlflash_release *release)
> +{
> + release->hdr = detach->hdr;
> + release->context_id = detach->context_id;
> +}
> +
> +/**
> + * create_local() - allocate and initialize a local LUN information structure
> + * @sdev: SCSI device associated with LUN.
> + * @wwid: World Wide Node Name for LUN.
> + *
> + * Return: Allocated local llun_info structure on success, NULL on failure
> + */
> +static struct llun_info *create_local(struct scsi_device *sdev, u8 *wwid)
> +{
> + struct llun_info *lli = NULL;
> +
> + lli = kzalloc(sizeof(*lli), GFP_KERNEL);
> + if (unlikely(!lli)) {
> + pr_err("%s: could not allocate lli\n", __func__);
> + goto out;
> + }
> +
> + lli->sdev = sdev;
> + lli->newly_created = true;
> + lli->host_no = sdev->host->host_no;
> +
> + memcpy(lli->wwid, wwid, DK_CXLFLASH_MANAGE_LUN_WWID_LEN);
> +out:
> + return lli;
> +}
> +
> +/**
> + * create_global() - allocate and initialize a global LUN information structure
> + * @sdev: SCSI device associated with LUN.
> + * @wwid: World Wide Node Name for LUN.
> + *
> + * Return: Allocated global glun_info structure on success, NULL on failure
> + */
> +static struct glun_info *create_global(struct scsi_device *sdev, u8 *wwid)
> +{
> + struct glun_info *gli = NULL;
> +
> + gli = kzalloc(sizeof(*gli), GFP_KERNEL);
> + if (unlikely(!gli)) {
> + pr_err("%s: could not allocate gli\n", __func__);
> + goto out;
> + }
> +
> + memcpy(gli->wwid, wwid, DK_CXLFLASH_MANAGE_LUN_WWID_LEN);
> +out:
> + return gli;
> +}
> +
> +/**
> + * lookup_local() - find a local LUN information structure by WWID
> + * @cfg: Internal structure associated with the host.
> + * @wwid: WWID associated with LUN.
> + *
> + * Return: Found local lun_info structure on success, NULL on failure
> + */
> +static struct llun_info *lookup_local(struct cxlflash_cfg *cfg, u8 *wwid)
> +{
> + struct llun_info *lli, *temp;
> + ulong lock_flags;
> +
> + spin_lock_irqsave(&cfg->slock, lock_flags);
> +
> + list_for_each_entry_safe(lli, temp, &cfg->lluns, list)
> + if (!memcmp(lli->wwid, wwid, DK_CXLFLASH_MANAGE_LUN_WWID_LEN)) {
> + lli->newly_created = false;
> + spin_unlock_irqrestore(&cfg->slock, lock_flags);
> + return lli;
> + }
> +
> + spin_unlock_irqrestore(&cfg->slock, lock_flags);
> + return NULL;
> +}
> +
> +/**
> + * lookup_global() - find a global LUN information structure by WWID
> + * @wwid: WWID associated with LUN.
> + *
> + * Return: Found global lun_info structure on success, NULL on failure
> + */
> +static struct glun_info *lookup_global(u8 *wwid)
> +{
> + struct glun_info *gli, *temp;
> + ulong lock_flags;
> +
> + spin_lock_irqsave(&global.slock, lock_flags);
> +
> + list_for_each_entry_safe(gli, temp, &global.gluns, list)
> + if (!memcmp(gli->wwid, wwid, DK_CXLFLASH_MANAGE_LUN_WWID_LEN)) {
> + spin_unlock_irqrestore(&global.slock, lock_flags);
> + return gli;
> + }
> +
> + spin_unlock_irqrestore(&global.slock, lock_flags);
> + return NULL;
> +}
> +
> +/**
> + * lookup_lun() - find or create a local LUN information structure
> + * @sdev: SCSI device associated with LUN.
> + * @wwid: WWID associated with LUN.
> + *
> + * When a local LUN is not found and a global LUN is also not found, both
> + * a global LUN and local LUN are created. The global LUN is added to the
> + * global list and the local LUN is returned.
> + *
> + * Return: Found/Allocated local lun_info structure on success, NULL on failure
> + */
> +static struct llun_info *lookup_lun(struct scsi_device *sdev, u8 *wwid)

Should this been lookup_and_create_lun()? lookup_lun() does something quite
differnt to lookup_local() despite being named simlarly.

> +{
> + struct llun_info *lli = NULL;
> + struct glun_info *gli = NULL;
> + struct Scsi_Host *shost = sdev->host;
> + struct cxlflash_cfg *cfg = shost_priv(shost);
> + ulong lock_flags;
> +
> + if (unlikely(!wwid))
> + goto out;
> +
> + lli = lookup_local(cfg, wwid);
> + if (lli)
> + goto out;
> +
> + lli = create_local(sdev, wwid);
> + if (unlikely(!lli))
> + goto out;
> +
> + gli = lookup_global(wwid);
> + if (gli) {
> + lli->parent = gli;
> + spin_lock_irqsave(&cfg->slock, lock_flags);
> + list_add(&lli->list, &cfg->lluns);
> + spin_unlock_irqrestore(&cfg->slock, lock_flags);
> + goto out;
> + }
> +
> + gli = create_global(sdev, wwid);
> + if (unlikely(!gli)) {
> + kfree(lli);
> + lli = NULL;
> + goto out;
> + }
> +
> + lli->parent = gli;
> + spin_lock_irqsave(&cfg->slock, lock_flags);
> + list_add(&lli->list, &cfg->lluns);
> + spin_unlock_irqrestore(&cfg->slock, lock_flags);
> +
> + spin_lock_irqsave(&global.slock, lock_flags);
> + list_add(&gli->list, &global.gluns);
> + spin_unlock_irqrestore(&global.slock, lock_flags);
> +
> +out:
> + pr_debug("%s: returning %p\n", __func__, lli);
> + return lli;
> +}
> +
> +/**
> + * cxlflash_term_luns() - Delete all entries from local lun list, free.
> + * @cfg: Internal structure associated with the host.
> + */
> +void cxlflash_term_luns(struct cxlflash_cfg *cfg)

This just does local luns?

> +{
> + struct llun_info *lli, *temp;
> + ulong lock_flags;
> +
> + spin_lock_irqsave(&cfg->slock, lock_flags);
> + list_for_each_entry_safe(lli, temp, &cfg->lluns, list) {
> + list_del(&lli->list);
> + kfree(lli);
> + }
> + spin_unlock_irqrestore(&cfg->slock, lock_flags);
> +}
> +
> +/**
> + * cxlflash_list_init() - initializes the global LUN list
> + */
> +void cxlflash_list_init(void)
> +{
> + INIT_LIST_HEAD(&global.gluns);
> + spin_lock_init(&global.slock);
> + global.err_page = NULL;
> +}
> +
> +/**
> + * cxlflash_list_terminate() - frees resources associated with global LUN list
> + */
> +void cxlflash_list_terminate(void)
> +{
> + struct glun_info *gli, *temp;
> + ulong flags = 0;
> +
> + spin_lock_irqsave(&global.slock, flags);
> + list_for_each_entry_safe(gli, temp, &global.gluns, list) {
> + list_del(&gli->list);
> + kfree(gli);
> + }
> +
> + if (global.err_page) {
> + __free_page(global.err_page);
> + global.err_page = NULL;
> + }
> + spin_unlock_irqrestore(&global.slock, flags);
> +}
> +
> +/**
> + * cxlflash_stop_term_user_contexts() - stops/terminates known user contexts
> + * @cfg: Internal structure associated with the host.
> + *
> + * When the host needs to go down, all users must be quiesced and their
> + * memory freed. This is accomplished by putting the contexts in error
> + * state which will notify the user and let them 'drive' the teardown.
> + * Meanwhile, this routine camps until all user contexts have been removed.
> + */
> +void cxlflash_stop_term_user_contexts(struct cxlflash_cfg *cfg)
> +{
> + int i, found;
> +
> + cxlflash_mark_contexts_error(cfg);
> +
> + while (true) {
> + found = false;
> +
> + for (i = 0; i < MAX_CONTEXT; i++)
> + if (cfg->ctx_tbl[i]) {
> + found = true;
> + break;
> + }
> +
> + if (!found && list_empty(&cfg->ctx_err_recovery))
> + return;
> +
> + pr_debug("%s: Wait for user context to quiesce...\n", __func__);
> + wake_up_all(&cfg->limbo_waitq);
> + ssleep(1);

Why 1 sec and why in a loop? Can't you poll/wait for completion somewhere?

> + }
> +}
> +
> +/**
> + * find_error_context() - locates a context by cookie on the error recovery list
> + * @cfg: Internal structure associated with the host.
> + * @rctxid: Desired context by id.
> + * @file: Desired context by file.
> + *
> + * Return: Found context on success, NULL on failure
> + */
> +static struct ctx_info *find_error_context(struct cxlflash_cfg *cfg, u64 rctxid,
> + struct file *file)
> +{
> + struct ctx_info *ctxi;
> +
> + list_for_each_entry(ctxi, &cfg->ctx_err_recovery, list)
> + if ((ctxi->ctxid == rctxid) || (ctxi->file == file))
> + return ctxi;
> +
> + return NULL;
> +}
> +
> +/**
> + * get_context() - obtains a validated and locked context reference
> + * @cfg: Internal structure associated with the host.
> + * @rctxid: Desired context (raw, undecoded format).
> + * @arg: LUN information or file associated with request.
> + * @ctx_ctrl: Control information to 'steer' desired lookup.
> + *
> + * NOTE: despite the name pid, in linux, current->pid actually refers
> + * to the lightweight process id (tid) and can change if the process is
> + * multi threaded. The tgid remains constant for the process and only changes
> + * when the process of fork. For all intents and purposes, think of tgid
> + * as a pid in the traditional sense.
> + *
> + * Return: Validated context on success, NULL on failure
> + */
> +struct ctx_info *get_context(struct cxlflash_cfg *cfg, u64 rctxid,
> + void *arg, enum ctx_ctrl ctx_ctrl)
> +{
> + struct ctx_info *ctxi = NULL;
> + struct lun_access *lun_access = NULL;
> + struct file *file = NULL;
> + struct llun_info *lli = arg;
> + u64 ctxid = DECODE_CTXID(rctxid);
> + int rc;
> + pid_t pid = current->tgid, ctxpid = 0;
> +
> + if (ctx_ctrl & CTX_CTRL_FILE) {
> + lli = NULL;
> + file = (struct file *)arg;
> + }
> +
> + if (ctx_ctrl & CTX_CTRL_CLONE)
> + pid = current->parent->tgid;
> +
> + if (likely(ctxid < MAX_CONTEXT)) {
> +retry:
> + rc = mutex_lock_interruptible(&cfg->ctx_tbl_list_mutex);
> + if (rc)
> + goto out;
> +
> + ctxi = cfg->ctx_tbl[ctxid];
> + if (ctxi)
> + if ((file && (ctxi->file != file)) ||
> + (!file && (ctxi->ctxid != rctxid)))
> + ctxi = NULL;
> +
> + if ((ctx_ctrl & CTX_CTRL_ERR) ||
> + (!ctxi && (ctx_ctrl & CTX_CTRL_ERR_FALLBACK)))
> + ctxi = find_error_context(cfg, rctxid, file);
> + if (!ctxi) {
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + goto out;
> + }
> +
> + /*
> + * Need to acquire ownership of the context while still under
> + * the table/list lock to serialize with a remove thread. Use
> + * the 'try' to avoid stalling the table/list lock for a single
> + * context.
> + */
> + rc = mutex_trylock(&ctxi->mutex);
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + if (!rc)
> + goto retry;

Please just create a loop rather than this goto retry.

> +
> + if (ctxi->unavail)
> + goto denied;
> +
> + ctxpid = ctxi->pid;
> + if (likely(!(ctx_ctrl & CTX_CTRL_NOPID)))
> + if (pid != ctxpid)
> + goto denied;
> +
> + if (lli) {
> + list_for_each_entry(lun_access, &ctxi->luns, list)
> + if (lun_access->lli == lli)
> + goto out;
> + goto denied;
> + }
> + }
> +
> +out:
> + pr_debug("%s: rctxid=%016llX ctxinfo=%p ctxpid=%u pid=%u ctx_ctrl=%u\n",
> + __func__, rctxid, ctxi, ctxpid, pid, ctx_ctrl);
> +
> + return ctxi;
> +
> +denied:
> + mutex_unlock(&ctxi->mutex);
> + ctxi = NULL;
> + goto out;
> +}
> +
> +/**
> + * afu_attach() - attach a context to the AFU
> + * @cfg: Internal structure associated with the host.
> + * @ctxi: Context to attach.
> + *
> + * Upon setting the context capabilities, they must be confirmed with
> + * a read back operation as the context might have been closed since
> + * the mailbox was unlocked. When this occurs, registration is failed.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int afu_attach(struct cxlflash_cfg *cfg, struct ctx_info *ctxi)
> +{
> + struct afu *afu = cfg->afu;
> + struct sisl_ctrl_map *ctrl_map = ctxi->ctrl_map;
> + int rc = 0;
> + u64 val;
> +
> + /* Unlock cap and restrict user to read/write cmds in translated mode */
> + readq_be(&ctrl_map->mbox_r);
> + val = (SISL_CTX_CAP_READ_CMD | SISL_CTX_CAP_WRITE_CMD);
> + writeq_be(val, &ctrl_map->ctx_cap);
> + val = readq_be(&ctrl_map->ctx_cap);
> + if (val != (SISL_CTX_CAP_READ_CMD | SISL_CTX_CAP_WRITE_CMD)) {
> + pr_err("%s: ctx may be closed val=%016llX\n", __func__, val);
> + rc = -EAGAIN;
> + goto out;
> + }
> +
> + /* Set up MMIO registers pointing to the RHT */
> + writeq_be((u64)ctxi->rht_start, &ctrl_map->rht_start);
> + val = SISL_RHT_CNT_ID((u64)MAX_RHT_PER_CONTEXT, (u64)(afu->ctx_hndl));
> + writeq_be(val, &ctrl_map->rht_cnt_id);
> +out:
> + pr_debug("%s: returning rc=%d\n", __func__, rc);
> + return rc;
> +}
> +
> +/**
> + * read_cap16() - issues a SCSI READ_CAP16 command
> + * @sdev: SCSI device associated with LUN.
> + * @lli: LUN destined for capacity request.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int read_cap16(struct scsi_device *sdev, struct llun_info *lli)
> +{
> + struct glun_info *gli = lli->parent;
> + u8 *buf = NULL;
> + u8 *cmd_buf = NULL;
> + u8 *scsi_cmd = NULL;
> + u8 *sense_buf = NULL;
> + int rc = 0;
> + int result = 0;
> + int retry_cnt = 0;
> + u32 tout = (MC_DISCOVERY_TIMEOUT * HZ);
> + size_t size;
> +
> + size = CMD_BUFSIZE + MAX_COMMAND_SIZE + SCSI_SENSE_BUFFERSIZE;
> +retry:
> + buf = kzalloc(size, GFP_KERNEL);
> + if (unlikely(!buf)) {
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + cmd_buf = buf;
> + scsi_cmd = cmd_buf + CMD_BUFSIZE;
> + sense_buf = scsi_cmd + MAX_COMMAND_SIZE;
> +
> + scsi_cmd[0] = SERVICE_ACTION_IN_16; /* read cap(16) */
> + scsi_cmd[1] = SAI_READ_CAPACITY_16; /* service action */
> + put_unaligned_be32(CMD_BUFSIZE, &scsi_cmd[10]);
> +
> + pr_debug("%s: %ssending cmd(0x%x)\n", __func__, retry_cnt ? "re" : "",
> + scsi_cmd[0]);
> +
> + result = scsi_execute(sdev, scsi_cmd, DMA_FROM_DEVICE, cmd_buf,
> + CMD_BUFSIZE, sense_buf, tout, 5, 0, NULL);
> +
> + if (driver_byte(result) == DRIVER_SENSE) {
> + result &= ~(0xFF<<24); /* DRIVER_SENSE is not an error */
> + if (result & SAM_STAT_CHECK_CONDITION) {
> + struct scsi_sense_hdr sshdr;
> +
> + scsi_normalize_sense(sense_buf, SCSI_SENSE_BUFFERSIZE,
> + &sshdr);
> + switch (sshdr.sense_key) {
> + case NO_SENSE:
> + case RECOVERED_ERROR:
> + /* fall through */
> + case NOT_READY:
> + result &= ~SAM_STAT_CHECK_CONDITION;
> + break;
> + case UNIT_ATTENTION:
> + switch (sshdr.asc) {
> + case 0x29: /* Power on Reset or Device Reset */
> + /* fall through */
> + case 0x2A: /* Device capacity changed */
> + case 0x3F: /* Report LUNs changed */
> + /* Retry the command once more */
> + if (retry_cnt++ < 1) {
> + kfree(buf);
> + goto retry;
> + }
> + }
> + break;
> + default:
> + break;
> + }
> + }
> + }
> +
> + if (result) {
> + pr_err("%s: command failed, result=0x%x\n", __func__, result);
> + rc = -EIO;
> + goto out;
> + }
> +
> + /*
> + * Read cap was successful, grab values from the buffer;
> + * note that we don't need to worry about unaligned access
> + * as the buffer is allocated on an aligned boundary.
> + */
> + spin_lock(&gli->slock);
> + gli->max_lba = be64_to_cpu(*((u64 *)&cmd_buf[0]));
> + gli->blk_len = be32_to_cpu(*((u32 *)&cmd_buf[8]));
> + spin_unlock(&gli->slock);
> +
> +out:
> + kfree(buf);
> + pr_debug("%s: maxlba=%lld blklen=%d rc=%d\n", __func__,
> + gli->max_lba, gli->blk_len, rc);
> + return rc;
> +}
> +
> +/**
> + * get_rhte() - obtains validated resource handle table entry reference
> + * @ctxi: Context owning the resource handle.
> + * @rhndl: Resource handle associated with entry.
> + * @lli: LUN associated with request.
> + *
> + * Return: Validated RHTE on success, NULL on failure
> + */
> +struct sisl_rht_entry *get_rhte(struct ctx_info *ctxi, res_hndl_t rhndl,
> + struct llun_info *lli)
> +{
> + struct sisl_rht_entry *rhte = NULL;
> +
> + if (unlikely(!ctxi->rht_start)) {
> + pr_err("%s: Context does not have allocated RHT!\n", __func__);
> + goto out;
> + }
> +
> + if (unlikely(rhndl >= MAX_RHT_PER_CONTEXT)) {
> + pr_err("%s: Bad resource handle! (%d)\n", __func__, rhndl);
> + goto out;
> + }
> +
> + if (unlikely(ctxi->rht_lun[rhndl] != lli)) {
> + pr_err("%s: Bad resource handle LUN! (%d)\n", __func__, rhndl);
> + goto out;
> + }
> +
> + rhte = &ctxi->rht_start[rhndl];
> + if (unlikely(rhte->nmask == 0)) {
> + pr_err("%s: Unopened resource handle! (%d)\n", __func__, rhndl);
> + rhte = NULL;
> + goto out;
> + }
> +
> +out:
> + return rhte;
> +}
> +
> +/**
> + * rhte_checkout() - obtains free/empty resource handle table entry
> + * @ctxi: Context owning the resource handle.
> + * @lli: LUN associated with request.
> + *
> + * Return: Free RHTE on success, NULL on failure
> + */
> +struct sisl_rht_entry *rhte_checkout(struct ctx_info *ctxi,
> + struct llun_info *lli)
> +{
> + struct sisl_rht_entry *rhte = NULL;
> + int i;
> +
> + /* Find a free RHT entry */
> + for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
> + if (ctxi->rht_start[i].nmask == 0) {
> + rhte = &ctxi->rht_start[i];
> + ctxi->rht_out++;
> + break;
> + }
> +
> + if (likely(rhte))
> + ctxi->rht_lun[i] = lli;
> +
> + pr_debug("%s: returning rhte=%p (%d)\n", __func__, rhte, i);
> + return rhte;
> +}
> +
> +/**
> + * rhte_checkin() - releases a resource handle table entry
> + * @ctxi: Context owning the resource handle.
> + * @rhte: RHTE to release.
> + */
> +void rhte_checkin(struct ctx_info *ctxi,
> + struct sisl_rht_entry *rhte)
> +{
> + u32 rsrc_handle = rhte - ctxi->rht_start;
> +
> + rhte->nmask = 0;
> + rhte->fp = 0;
> + ctxi->rht_out--;
> + ctxi->rht_lun[rsrc_handle] = NULL;
> +}
> +
> +/**
> + * rhte_format1() - populates a RHTE for format 1
> + * @rhte: RHTE to populate.
> + * @lun_id: LUN ID of LUN associated with RHTE.
> + * @perm: Desired permissions for RHTE.
> + * @port_sel: Port selection mask
> + */
> +static void rht_format1(struct sisl_rht_entry *rhte, u64 lun_id, u32 perm,
> + u32 port_sel)
> +{
> + /*
> + * Populate the Format 1 RHT entry for direct access (physical
> + * LUN) using the synchronization sequence defined in the
> + * SISLite specification.
> + */
> + struct sisl_rht_entry_f1 dummy = { 0 };
> + struct sisl_rht_entry_f1 *rhte_f1 = (struct sisl_rht_entry_f1 *)rhte;
> +
> + memset(rhte_f1, 0, sizeof(*rhte_f1));
> + rhte_f1->fp = SISL_RHT_FP(1U, 0);
> + dma_wmb(); /* Make setting of format bit visible */
> +
> + rhte_f1->lun_id = lun_id;
> + dma_wmb(); /* Make setting of LUN id visible */
> +
> + /*
> + * Use a dummy RHT Format 1 entry to build the second dword
> + * of the entry that must be populated in a single write when
> + * enabled (valid bit set to TRUE).
> + */
> + dummy.valid = 0x80;
> + dummy.fp = SISL_RHT_FP(1U, perm);
> + dummy.port_sel = port_sel;
> + rhte_f1->dw = dummy.dw;
> +
> + dma_wmb(); /* Make remaining RHT entry fields visible */
> +}
> +
> +/**
> + * cxlflash_lun_attach() - attaches a user to a LUN and manages the LUN's mode
> + * @gli: LUN to attach.
> + * @mode: Desired mode of the LUN.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +int cxlflash_lun_attach(struct glun_info *gli, enum lun_mode mode)
> +{
> + int rc = 0;
> +
> + spin_lock(&gli->slock);
> + if (gli->mode == MODE_NONE)
> + gli->mode = mode;
> + else if (gli->mode != mode) {
> + pr_err("%s: LUN operating in mode %d, requested mode %d\n",
> + __func__, gli->mode, mode);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + gli->users++;
> + WARN_ON(gli->users <= 0);
> +out:
> + pr_debug("%s: Returning rc=%d gli->mode=%u gli->users=%u\n",
> + __func__, rc, gli->mode, gli->users);
> + spin_unlock(&gli->slock);
> + return rc;
> +}
> +
> +/**
> + * cxlflash_lun_detach() - detaches a user from a LUN and resets the LUN's mode
> + * @gli: LUN to detach.
> + *
> + * When resetting the mode, terminate block allocation resources as they
> + * are no longer required (service is safe to call even when block allocation
> + * resources were not present - such as when transitioning from physical mode).
> + * These resources will be reallocated when needed (subsequent transition to
> + * virtual mode).
> + */
> +void cxlflash_lun_detach(struct glun_info *gli)
> +{
> + spin_lock(&gli->slock);
> + WARN_ON(gli->mode == MODE_NONE);
> + if (--gli->users == 0)
> + gli->mode = MODE_NONE;
> + pr_debug("%s: gli->users=%u\n", __func__, gli->users);
> + WARN_ON(gli->users < 0);
> + spin_unlock(&gli->slock);
> +}
> +
> +/**
> + * _cxlflash_disk_release() - releases the specified resource entry
> + * @sdev: SCSI device associated with LUN.
> + * @ctxi: Context owning resources.
> + * @release: Release ioctl data structure.
> + *
> + * For LUN's in virtual mode, the virtual lun associated with the specified
> + * resource handle is resized to 0 prior to releasing the RHTE. Note that the
> + * AFU sync should _not_ be performed when the context is sitting on the error
> + * recovery list. A context on the error recovery list is not known to the AFU
> + * due to reset. When the context is recovered, it will be reattached and made
> + * known again to the AFU.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +int _cxlflash_disk_release(struct scsi_device *sdev,
> + struct ctx_info *ctxi,
> + struct dk_cxlflash_release *release)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct llun_info *lli = sdev->hostdata;
> + struct glun_info *gli = lli->parent;
> + struct afu *afu = cfg->afu;
> + bool unlock_ctx = false;
> +
> + res_hndl_t rhndl = release->rsrc_handle;
> +
> + int rc = 0;
> + u64 ctxid = DECODE_CTXID(release->context_id),
> + rctxid = release->context_id;
> +
> + struct sisl_rht_entry *rhte;
> + struct sisl_rht_entry_f1 *rhte_f1;
> +
> + pr_debug("%s: ctxid=%llu rhndl=0x%llx gli->mode=%u gli->users=%u\n",
> + __func__, ctxid, release->rsrc_handle, gli->mode, gli->users);
> +
> + if (!ctxi) {
> + ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%llu)\n", __func__, ctxid);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + unlock_ctx = true;
> + }
> +
> + rhte = get_rhte(ctxi, rhndl, lli);
> + if (unlikely(!rhte)) {
> + pr_err("%s: Bad resource handle! (%d)\n", __func__, rhndl);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + /*
> + * Resize to 0 for virtual LUNS by setting the size
> + * to 0. This will clear LXT_START and LXT_CNT fields
> + * in the RHT entry and properly sync with the AFU.
> + *
> + * Afterwards we clear the remaining fields.
> + */
> + switch (gli->mode) {
> + case MODE_PHYSICAL:
> + /*
> + * Clear the Format 1 RHT entry for direct access
> + * (physical LUN) using the synchronization sequence
> + * defined in the SISLite specification.
> + */
> + rhte_f1 = (struct sisl_rht_entry_f1 *)rhte;
> +
> + rhte_f1->valid = 0;
> + dma_wmb(); /* Make revocation of RHT entry visible */
> +
> + rhte_f1->lun_id = 0;
> + dma_wmb(); /* Make clearing of LUN id visible */
> +
> + rhte_f1->dw = 0;
> + dma_wmb(); /* Make RHT entry bottom-half clearing visible */
> +
> + if (!ctxi->err_recovery_active)
> + cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
> + break;
> + default:
> + WARN(1, "Unsupported LUN mode!");
> + goto out;
> + }
> +
> + rhte_checkin(ctxi, rhte);
> + cxlflash_lun_detach(gli);
> +
> +out:
> + if (unlock_ctx)
> + mutex_unlock(&ctxi->mutex);

Where is the matching lock for this?

> + pr_debug("%s: returning rc=%d\n", __func__, rc);
> + return rc;
> +}
> +
> +int cxlflash_disk_release(struct scsi_device *sdev,
> + struct dk_cxlflash_release *release)
> +{
> + return _cxlflash_disk_release(sdev, NULL, release);
> +}
> +
> +/**
> + * destroy_context() - releases a context
> + * @cfg: Internal structure associated with the host.
> + * @ctxi: Context to release.
> + *
> + * Note that the rht_lun member of the context was cut from a single
> + * allocation when the context was created and therefore does not need
> + * to be explicitly freed. Also note that we conditionally check for the
> + * existence of the context control map before clearing the RHT registers
> + * and context capbilities because it is possible to destroy a context
> + * while the context is in the error state (previous mapping was removed
> + * [so we don't have to worry about clearing] and context is waiting for
> + * a new mapping).
> + */
> +static void destroy_context(struct cxlflash_cfg *cfg,
> + struct ctx_info *ctxi)
> +{
> + struct afu *afu = cfg->afu;
> +
> + WARN_ON(!list_empty(&ctxi->luns));
> +
> + /* Clear RHT registers and drop all capabilities for this context */
> + if (afu->afu_map && ctxi->ctrl_map) {
> + writeq_be(0, &ctxi->ctrl_map->rht_start);
> + writeq_be(0, &ctxi->ctrl_map->rht_cnt_id);
> + writeq_be(0, &ctxi->ctrl_map->ctx_cap);
> + }
> +
> + /*
> + * Free the RHT memory and context; note that rht_lun
> + * was carved from the same memory as the context.
> + */
> + free_page((ulong)ctxi->rht_start);
> + kfree(ctxi);
> + atomic_dec_if_positive(&cfg->num_user_contexts);
> +}
> +
> +/**
> + * create_context() - allocates and initializes a context
> + * @cfg: Internal structure associated with the host.
> + * @ctx: Previously obtained CXL context reference.
> + * @ctxid: Previously obtained process element associated with CXL context.
> + * @adap_fd: Previously obtained adapter fd associated with CXL context.
> + * @file: Previously obtained file associated with CXL context.
> + * @perms: User-specified permissions.
> + *
> + * The context's mutex is locked when an allocated context is returned.
> + *
> + * Return: Allocated context on success, NULL on failure
> + */
> +static struct ctx_info *create_context(struct cxlflash_cfg *cfg,
> + struct cxl_context *ctx, int ctxid,
> + int adap_fd, struct file *file,
> + u32 perms)
> +{
> + char *tmp = NULL;
> + size_t size;
> + struct afu *afu = cfg->afu;
> + struct ctx_info *ctxi = NULL;
> + struct sisl_rht_entry *rhte;
> +
> + size = (MAX_RHT_PER_CONTEXT * sizeof(*ctxi->rht_lun));
> + size += sizeof(*ctxi);
> +
> + tmp = kzalloc(size, GFP_KERNEL);

Just do two allocs. One for ctxi and one for rht_lun. This is overly
complicated.

> + if (unlikely(!tmp)) {
> + pr_err("%s: Unable to allocate context! (%ld)\n",
> + __func__, size);
> + goto out;
> + }
> +
> + rhte = (struct sisl_rht_entry *)get_zeroed_page(GFP_KERNEL);
> + if (unlikely(!rhte)) {
> + pr_err("%s: Unable to allocate RHT!\n", __func__);
> + goto err;
> + }
> +
> + ctxi = (struct ctx_info *)tmp;
> + tmp += sizeof(*ctxi);
> + ctxi->rht_lun = (struct llun_info **)tmp;

Yuck... just do two allocs rather than this throbbing.

> + ctxi->rht_start = rhte;
> + ctxi->rht_perms = perms;
> +
> + ctxi->ctrl_map = &afu->afu_map->ctrls[ctxid].ctrl;
> + ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
> + ctxi->lfd = adap_fd;
> + ctxi->pid = current->tgid; /* tgid = pid */
> + ctxi->ctx = ctx;
> + ctxi->file = file;
> + mutex_init(&ctxi->mutex);
> + INIT_LIST_HEAD(&ctxi->luns);
> + INIT_LIST_HEAD(&ctxi->list); /* initialize for list_empty() */
> +
> + atomic_inc(&cfg->num_user_contexts);
> + mutex_lock(&ctxi->mutex);
> +out:
> + return ctxi;
> +
> +err:
> + kfree(tmp);
> + goto out;
> +}
> +
> +/**
> + * _cxlflash_disk_detach() - detaches a LUN from a context
> + * @sdev: SCSI device associated with LUN.
> + * @ctxi: Context owning resources.
> + * @detach: Detach ioctl data structure.
> + *
> + * As part of the detach, all per-context resources associated with the LUN
> + * are cleaned up. When detaching the last LUN for a context, the context
> + * itself is cleaned up and released.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int _cxlflash_disk_detach(struct scsi_device *sdev,
> + struct ctx_info *ctxi,
> + struct dk_cxlflash_detach *detach)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct llun_info *lli = sdev->hostdata;
> + struct lun_access *lun_access, *t;
> + struct dk_cxlflash_release rel;
> + bool unlock_ctx = false;
> +
> + int i;
> + int rc = 0;
> + int lfd;
> + u64 ctxid = DECODE_CTXID(detach->context_id),
> + rctxid = detach->context_id;
> +
> + pr_debug("%s: ctxid=%llu\n", __func__, ctxid);
> +
> + if (!ctxi) {
> + ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%llu)\n", __func__, ctxid);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + unlock_ctx = true;
> + }
> +
> + /* Cleanup outstanding resources tied to this LUN */
> + if (ctxi->rht_out) {
> + marshal_det_to_rele(detach, &rel);
> + for (i = 0; i < MAX_RHT_PER_CONTEXT; i++) {
> + if (ctxi->rht_lun[i] == lli) {
> + rel.rsrc_handle = i;
> + _cxlflash_disk_release(sdev, ctxi, &rel);
> + }
> +
> + /* No need to loop further if we're done */
> + if (ctxi->rht_out == 0)
> + break;
> + }
> + }
> +
> + /* Take our LUN out of context, free the node */
> + list_for_each_entry_safe(lun_access, t, &ctxi->luns, list)
> + if (lun_access->lli == lli) {
> + list_del(&lun_access->list);
> + kfree(lun_access);
> + lun_access = NULL;
> + break;
> + }
> +
> + /* Tear down context following last LUN cleanup */
> + if (list_empty(&ctxi->luns)) {
> + ctxi->unavail = true;
> + mutex_unlock(&ctxi->mutex);
> + mutex_lock(&cfg->ctx_tbl_list_mutex);
> + mutex_lock(&ctxi->mutex);
> +
> + /* Might not have been in error list so conditionally remove */
> + if (!list_empty(&ctxi->list))
> + list_del(&ctxi->list);
> + cfg->ctx_tbl[ctxid] = NULL;
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + mutex_unlock(&ctxi->mutex);
> +
> + lfd = ctxi->lfd;
> + destroy_context(cfg, ctxi);
> + ctxi = NULL;
> + unlock_ctx = false;
> +
> + /*
> + * As a last step, clean up external resources when not
> + * already on an external cleanup thread, ie: close(adap_fd).
> + *
> + * NOTE: this will free up the context from the CXL services,
> + * allowing it to dole out the same context_id on a future
> + * (or even currently in-flight) disk_attach operation.
> + */
> + if (lfd != -1)
> + sys_close(lfd);
> + }
> +
> +out:
> + if (unlock_ctx)
> + mutex_unlock(&ctxi->mutex);

Where is the matching lock for this?

> + pr_debug("%s: returning rc=%d\n", __func__, rc);
> + return rc;
> +}
> +
> +static int cxlflash_disk_detach(struct scsi_device *sdev,
> + struct dk_cxlflash_detach *detach)
> +{
> + return _cxlflash_disk_detach(sdev, NULL, detach);
> +}
> +
> +/**
> + * cxlflash_cxl_release() - release handler for adapter file descriptor
> + * @inode: Filesystem inode associated with fd.
> + * @file: File installed with adapter file descriptor.
> + *
> + * This routine is the release handler for the fops registered with
> + * the CXL services on an initial attach for a context. It is called
> + * when a close is performed on the adapter file descriptor returned
> + * to the user. Programmatically, the user is not required to perform
> + * the close, as it is handled internally via the detach ioctl when
> + * a context is being removed. Note that nothing prevents the user
> + * from performing a close, but the user should be aware that doing
> + * so is considered catastrophic and subsequent usage of the superpipe
> + * API with previously saved off tokens will fail.
> + *
> + * When initiated from an external close (either by the user or via
> + * a process tear down), the routine derives the context reference
> + * and calls detach for each LUN associated with the context. The
> + * final detach operation will cause the context itself to be freed.
> + * Note that the saved off lfd is reset prior to calling detach to
> + * signify that the final detach should not perform a close.
> + *
> + * When initiated from a detach operation as part of the tear down
> + * of a context, the context is first completely freed and then the
> + * close is performed. This routine will fail to derive the context
> + * reference (due to the context having already been freed) and then
> + * call into the CXL release entry point.
> + *
> + * Thus, with exception to when the CXL process element (context id)
> + * lookup fails (a case that should theoretically never occur), every
> + * call into this routine results in a complete freeing of a context.
> + *
> + * As part of the detach, all per-context resources associated with the LUN
> + * are cleaned up. When detaching the last LUN for a context, the context
> + * itself is cleaned up and released.
> + *
> + * Return: 0 on success
> + */
> +static int cxlflash_cxl_release(struct inode *inode, struct file *file)
> +{
> + struct cxl_context *ctx = cxl_fops_get_context(file);
> + struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
> + cxl_fops);
> + struct ctx_info *ctxi = NULL;
> + struct dk_cxlflash_detach detach = { { 0 }, 0 };
> + struct lun_access *lun_access, *t;
> + enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
> + int ctxid;
> +
> + ctxid = cxl_process_element(ctx);
> + if (unlikely(ctxid < 0)) {
> + pr_err("%s: Context %p was closed! (%d)\n",
> + __func__, ctx, ctxid);
> + goto out;
> + }
> +
> + ctxi = get_context(cfg, ctxid, file, ctrl);
> + if (unlikely(!ctxi)) {
> + ctxi = get_context(cfg, ctxid, file, ctrl | CTX_CTRL_CLONE);
> + if (!ctxi) {
> + pr_debug("%s: Context %d already free!\n",
> + __func__, ctxid);
> + goto out_release;
> + }
> +
> + pr_debug("%s: Another process owns context %d!\n",
> + __func__, ctxid);
> + mutex_unlock(&ctxi->mutex);
> + goto out;
> + }
> +
> + pr_debug("%s: close(%d) for context %d\n",
> + __func__, ctxi->lfd, ctxid);
> +
> + /* Reset the file descriptor to indicate we're on a close() thread */
> + ctxi->lfd = -1;
> + detach.context_id = ctxi->ctxid;
> + list_for_each_entry_safe(lun_access, t, &ctxi->luns, list)
> + _cxlflash_disk_detach(lun_access->sdev, ctxi, &detach);
> +out_release:
> + cxl_fd_release(inode, file);
> +out:
> + pr_debug("%s: returning\n", __func__);
> + return 0;
> +}
> +
> +/**
> + * unmap_context() - clears a previously established mapping
> + * @ctxi: Context owning the mapping.
> + *
> + * This routine is used to switch between the error notification page
> + * (dummy page of all 1's) and the real mapping (established by the CXL
> + * fault handler).
> + */
> +static void unmap_context(struct ctx_info *ctxi)
> +{
> + unmap_mapping_range(ctxi->file->f_mapping, 0, 0, 1);
> +}
> +
> +/**
> + * get_err_page() - obtains and allocates the error notification page
> + *
> + * Return: error notification page on success, NULL on failure
> + */
> +static struct page *get_err_page(void)
> +{
> + struct page *err_page = global.err_page;
> + ulong flags = 0;
> +
> + if (unlikely(!err_page)) {
> + err_page = alloc_page(GFP_KERNEL);
> + if (unlikely(!err_page)) {
> + pr_err("%s: Unable to allocate err_page!\n", __func__);
> + goto out;
> + }
> +
> + memset(page_address(err_page), -1, PAGE_SIZE);
> +
> + /* Serialize update w/ other threads to avoid a leak */
> + spin_lock_irqsave(&global.slock, flags);
> + if (likely(!global.err_page))
> + global.err_page = err_page;
> + else {
> + __free_page(err_page);
> + err_page = global.err_page;
> + }
> + spin_unlock_irqrestore(&global.slock, flags);
> + }
> +
> +out:
> + pr_debug("%s: returning err_page=%p\n", __func__, err_page);
> + return err_page;
> +}
> +
> +/**
> + * cxlflash_mmap_fault() - mmap fault handler for adapter file descriptor
> + * @vma: VM area associated with mapping.
> + * @vmf: VM fault associated with current fault.
> + *
> + * To support error notification via MMIO, faults are 'caught' by this routine
> + * that was inserted before passing back the adapter file descriptor on attach.
> + * When a fault occurs, this routine evaluates if error recovery is active and
> + * if so, installs the error page to 'notify' the user about the error state.
> + * During normal operation, the fault is simply handled by the original fault
> + * handler that was installed by CXL services as part of initializing the
> + * adapter file descriptor. The VMA's page protection bits are toggled to
> + * indicate cached/not-cached depending on the memory backing the fault.
> + *
> + * Return: 0 on success, VM_FAULT_SIGBUS on failure
> + */
> +static int cxlflash_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> +{
> + struct file *file = vma->vm_file;
> + struct cxl_context *ctx = cxl_fops_get_context(file);
> + struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
> + cxl_fops);
> + struct ctx_info *ctxi = NULL;
> + struct page *err_page = NULL;
> + enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
> + int rc = 0;
> + int ctxid;
> +
> + ctxid = cxl_process_element(ctx);
> + if (unlikely(ctxid < 0)) {
> + pr_err("%s: Context %p was closed! (%d)\n",
> + __func__, ctx, ctxid);
> + goto err;
> + }
> +
> + ctxi = get_context(cfg, ctxid, file, ctrl);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%d)\n", __func__, ctxid);
> + goto err;
> + }
> +
> + pr_debug("%s: fault(%d) for context %d\n",
> + __func__, ctxi->lfd, ctxid);
> +
> + if (likely(!ctxi->err_recovery_active)) {
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> + rc = ctxi->cxl_mmap_vmops->fault(vma, vmf);
> + } else {
> + pr_debug("%s: err recovery active, use err_page!\n", __func__);
> +
> + err_page = get_err_page();
> + if (unlikely(!err_page)) {
> + pr_err("%s: Could not obtain error page!\n", __func__);
> + rc = VM_FAULT_RETRY;
> + goto out;
> + }
> +
> + get_page(err_page);
> + vmf->page = err_page;
> + vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
> + }
> +
> +out:
> + if (likely(ctxi))
> + mutex_unlock(&ctxi->mutex);
> + pr_debug("%s: returning rc=%d\n", __func__, rc);
> + return rc;
> +
> +err:
> + rc = VM_FAULT_SIGBUS;
> + goto out;
> +}
> +
> +/*
> + * Local MMAP vmops to 'catch' faults
> + */
> +static const struct vm_operations_struct cxlflash_mmap_vmops = {
> + .fault = cxlflash_mmap_fault,
> +};
> +
> +/**
> + * cxlflash_cxl_mmap() - mmap handler for adapter file descriptor
> + * @file: File installed with adapter file descriptor.
> + * @vma: VM area associated with mapping.
> + *
> + * Installs local mmap vmops to 'catch' faults for error notification support.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_cxl_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + struct cxl_context *ctx = cxl_fops_get_context(file);
> + struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
> + cxl_fops);
> + struct ctx_info *ctxi = NULL;
> + enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
> + int ctxid;
> + int rc = 0;
> +
> + ctxid = cxl_process_element(ctx);
> + if (unlikely(ctxid < 0)) {
> + pr_err("%s: Context %p was closed! (%d)\n",
> + __func__, ctx, ctxid);
> + rc = -EIO;
> + goto out;
> + }
> +
> + ctxi = get_context(cfg, ctxid, file, ctrl);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%d)\n", __func__, ctxid);
> + rc = -EIO;
> + goto out;
> + }
> +
> + pr_debug("%s: mmap(%d) for context %d\n", __func__, ctxi->lfd, ctxid);
> +
> + rc = cxl_fd_mmap(file, vma);
> + if (likely(!rc)) {
> + /* Insert ourself in the mmap fault handler path */
> + ctxi->cxl_mmap_vmops = vma->vm_ops;
> + vma->vm_ops = &cxlflash_mmap_vmops;
> + }
> +
> +out:
> + if (likely(ctxi))
> + mutex_unlock(&ctxi->mutex);

Where is the matching lock for this?

> + return rc;
> +}
> +
> +/*
> + * Local fops for adapter file descriptor
> + */
> +static const struct file_operations cxlflash_cxl_fops = {
> + .owner = THIS_MODULE,
> + .mmap = cxlflash_cxl_mmap,
> + .release = cxlflash_cxl_release,
> +};
> +
> +/**
> + * cxlflash_mark_contexts_error() - move contexts to error state and list
> + * @cfg: Internal structure associated with the host.
> + *
> + * A context is only moved over to the error list when there are no outstanding
> + * references to it. This ensures that a running operation has completed.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +int cxlflash_mark_contexts_error(struct cxlflash_cfg *cfg)
> +{
> + int i, rc = 0;
> + struct ctx_info *ctxi = NULL;
> +
> + mutex_lock(&cfg->ctx_tbl_list_mutex);
> +
> + for (i = 0; i < MAX_CONTEXT; i++) {
> + ctxi = cfg->ctx_tbl[i];
> + if (ctxi) {
> + mutex_lock(&ctxi->mutex);
> + cfg->ctx_tbl[i] = NULL;
> + list_add(&ctxi->list, &cfg->ctx_err_recovery);
> + ctxi->err_recovery_active = true;
> + ctxi->ctrl_map = NULL;
> + unmap_context(ctxi);
> + mutex_unlock(&ctxi->mutex);
> + }
> + }
> +
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + return rc;
> +}
> +
> +/*
> + * Dummy NULL fops
> + */
> +static const struct file_operations null_fops = {
> + .owner = THIS_MODULE,
> +};
> +
> +/**
> + * cxlflash_disk_attach() - attach a LUN to a context
> + * @sdev: SCSI device associated with LUN.
> + * @attach: Attach ioctl data structure.
> + *
> + * Creates a context and attaches LUN to it. A LUN can only be attached
> + * one time to a context (subsequent attaches for the same context/LUN pair
> + * are not supported). Additional LUNs can be attached to a context by
> + * specifying the 'reuse' flag defined in the cxlflash_ioctl.h header.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_disk_attach(struct scsi_device *sdev,
> + struct dk_cxlflash_attach *attach)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct afu *afu = cfg->afu;
> + struct llun_info *lli = sdev->hostdata;
> + struct glun_info *gli = lli->parent;
> + struct cxl_ioctl_start_work *work;
> + struct ctx_info *ctxi = NULL;
> + struct lun_access *lun_access = NULL;
> + int rc = 0;
> + u32 perms;
> + int ctxid = -1;
> + u64 rctxid = 0UL;
> + struct file *file;
> +
> + struct cxl_context *ctx;
> +
> + int fd = -1;
> +
> + /* On first attach set fileops */
> + if (atomic_read(&cfg->num_user_contexts) == 0)
> + cfg->cxl_fops = cxlflash_cxl_fops;
> +
> + if (attach->num_interrupts > 4) {
> + pr_err("%s: Cannot support this many interrupts %llu\n",
> + __func__, attach->num_interrupts);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + if (gli->max_lba == 0) {
> + pr_debug("%s: No capacity info yet for this LUN (%016llX)\n",
> + __func__, lli->lun_id[sdev->channel]);
> + rc = read_cap16(sdev, lli);
> + if (rc) {
> + pr_err("%s: Invalid device! (%d)\n", __func__, rc);
> + rc = -ENODEV;
> + goto out;
> + }
> + pr_debug("%s: LBA = %016llX\n", __func__, gli->max_lba);
> + pr_debug("%s: BLK_LEN = %08X\n", __func__, gli->blk_len);
> + }
> +
> + if (attach->hdr.flags & DK_CXLFLASH_ATTACH_REUSE_CONTEXT) {
> + rctxid = attach->context_id;
> + ctxi = get_context(cfg, rctxid, NULL, 0);
> + if (!ctxi) {
> + pr_err("%s: Bad context! (%016llX)\n",
> + __func__, rctxid);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + list_for_each_entry(lun_access, &ctxi->luns, list)
> + if (lun_access->lli == lli) {
> + pr_err("%s: Already attached!\n", __func__);
> + rc = -EINVAL;
> + goto out;
> + }
> + }
> +
> + lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
> + if (unlikely(!lun_access)) {
> + pr_err("%s: Unable to allocate lun_access!\n", __func__);
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + lun_access->lli = lli;
> + lun_access->sdev = sdev;
> +
> + /* Non-NULL context indicates reuse */
> + if (ctxi) {
> + pr_debug("%s: Reusing context for LUN! (%016llX)\n",
> + __func__, rctxid);
> + list_add(&lun_access->list, &ctxi->luns);
> + fd = ctxi->lfd;
> + goto out_attach;
> + }
> +
> + ctx = cxl_dev_context_init(cfg->dev);
> + if (unlikely(IS_ERR_OR_NULL(ctx))) {
> + pr_err("%s: Could not initialize context %p\n", __func__, ctx);
> + rc = -ENODEV;
> + goto err0;
> + }
> +
> + ctxid = cxl_process_element(ctx);
> + if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
> + pr_err("%s: ctxid (%d) invalid!\n", __func__, ctxid);
> + rc = -EPERM;
> + goto err1;
> + }
> +
> + file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);

You should create a new fops for each call here. We write the fops to fill it
out. I think it'll work as you have now but it's a bit dodgy.

> + if (unlikely(fd < 0)) {
> + rc = -ENODEV;
> + pr_err("%s: Could not get file descriptor\n", __func__);
> + goto err1;
> + }
> +
> + /* Translate read/write O_* flags from fcntl.h to AFU permission bits */
> + perms = SISL_RHT_PERM(attach->hdr.flags + 1);
> +
> + ctxi = create_context(cfg, ctx, ctxid, fd, file, perms);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Failed to create context! (%d)\n", __func__, ctxid);
> + goto err2;
> + }
> +
> + work = &ctxi->work;
> + work->num_interrupts = attach->num_interrupts;
> + work->flags = CXL_START_WORK_NUM_IRQS;
> +
> + rc = cxl_start_work(ctx, work);
> + if (unlikely(rc)) {
> + pr_debug("%s: Could not start context rc=%d\n", __func__, rc);
> + goto err3;
> + }
> +
> + rc = afu_attach(cfg, ctxi);
> + if (unlikely(rc)) {
> + pr_err("%s: Could not attach AFU rc %d\n", __func__, rc);
> + goto err4;
> + }
> +
> + /*
> + * No error paths after this point. Once the fd is installed it's
> + * visible to user space and can't be undone safely on this thread.
> + * There is no need to worry about a deadlock here because no one
> + * knows about us yet; we can be the only one holding our mutex.
> + */
> + list_add(&lun_access->list, &ctxi->luns);
> + mutex_unlock(&ctxi->mutex);

Where is the matching lock for this?

> + mutex_lock(&cfg->ctx_tbl_list_mutex);
> + mutex_lock(&ctxi->mutex);
> + cfg->ctx_tbl[ctxid] = ctxi;
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + fd_install(fd, file);
> +
> +out_attach:
> + attach->hdr.return_flags = 0;
> + attach->context_id = ctxi->ctxid;
> + attach->block_size = gli->blk_len;
> + attach->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
> + attach->last_lba = gli->max_lba;
> + attach->max_xfer = (sdev->host->max_sectors * 512) / gli->blk_len;
> +
> +out:
> + attach->adap_fd = fd;
> +
> + if (ctxi)
> + mutex_unlock(&ctxi->mutex);
> +
> + pr_debug("%s: returning ctxid=%d fd=%d bs=%lld rc=%d llba=%lld\n",
> + __func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
> + return rc;
> +
> +err4:
> + cxl_stop_context(ctx);
> +err3:
> + mutex_unlock(&ctxi->mutex);
> + destroy_context(cfg, ctxi);
> + ctxi = NULL;
> +err2:
> + /*
> + * Here, we're overriding the fops with a dummy all-NULL fops because
> + * fput() calls the release fop, which will cause us to mistakenly
> + * call into the CXL code. Rather than try to add yet more complexity
> + * to that routine (cxlflash_cxl_release) we should try to fix the
> + * issue here.
> + */
> + file->f_op = &null_fops;
> + fput(file);
> + put_unused_fd(fd);
> + fd = -1;
> +err1:
> + cxl_release_context(ctx);
> +err0:
> + kfree(lun_access);
> + goto out;
> +}
> +
> +/**
> + * cxlflash_manage_lun() - handles lun management activities
> + * @sdev: SCSI device associated with LUN.
> + * @manage: Manage ioctl data structure.
> + *
> + * This routine is used to notify the driver about a LUN's WWID and associate
> + * SCSI devices (sdev) with a global LUN instance. Additionally it serves to
> + * change a LUN's operating mode: legacy or superpipe.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_manage_lun(struct scsi_device *sdev,
> + struct dk_cxlflash_manage_lun *manage)
> +{
> + int rc = 0;
> + struct llun_info *lli = NULL;
> + u64 flags = manage->hdr.flags;
> + u32 chan = sdev->channel;
> +
> + lli = lookup_lun(sdev, manage->wwid);
> + pr_debug("%s: ENTER: WWID = %016llX%016llX, flags = %016llX li = %p\n",
> + __func__, get_unaligned_le64(&manage->wwid[0]),
> + get_unaligned_le64(&manage->wwid[8]),
> + manage->hdr.flags, lli);
> + if (unlikely(!lli)) {
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + if (flags & DK_CXLFLASH_MANAGE_LUN_ENABLE_SUPERPIPE) {
> + if (lli->newly_created)
> + lli->port_sel = CHAN2PORT(chan);
> + else
> + lli->port_sel = BOTH_PORTS;
> + /* Store off lun in unpacked, AFU-friendly format */
> + lli->lun_id[chan] = lun_to_lunid(sdev->lun);
> + sdev->hostdata = lli;
> + } else if (flags & DK_CXLFLASH_MANAGE_LUN_DISABLE_SUPERPIPE) {
> + if (lli->parent->mode != MODE_NONE)
> + rc = -EBUSY;
> + else
> + sdev->hostdata = NULL;
> + }
> +
> +out:
> + pr_debug("%s: returning rc=%d\n", __func__, rc);
> + return rc;
> +}
> +
> +/**
> + * recover_context() - recovers a context in error
> + * @cfg: Internal structure associated with the host.
> + * @ctxi: Context to release.
> + *
> + * Restablishes the state for a context-in-error.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int recover_context(struct cxlflash_cfg *cfg, struct ctx_info *ctxi)
> +{
> + int rc = 0;
> + int old_fd, fd = -1;
> + int ctxid = -1;
> + struct file *file;
> + struct cxl_context *ctx;
> + struct afu *afu = cfg->afu;
> +
> + ctx = cxl_dev_context_init(cfg->dev);
> + if (unlikely(IS_ERR_OR_NULL(ctx))) {
> + pr_err("%s: Could not initialize context %p\n", __func__, ctx);
> + rc = -ENODEV;
> + goto out;
> + }
> +
> + ctxid = cxl_process_element(ctx);
> + if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
> + pr_err("%s: ctxid (%d) invalid!\n", __func__, ctxid);
> + rc = -EPERM;
> + goto err1;
> + }
> +
> + file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
> + if (unlikely(fd < 0)) {
> + rc = -ENODEV;
> + pr_err("%s: Could not get file descriptor\n", __func__);
> + goto err1;
> + }
> +
> + rc = cxl_start_work(ctx, &ctxi->work);
> + if (unlikely(rc)) {
> + pr_err("%s: Could not start context rc=%d\n", __func__, rc);
> + goto err2;
> + }
> +
> + /* Update with new MMIO area based on updated context id */
> + ctxi->ctrl_map = &afu->afu_map->ctrls[ctxid].ctrl;
> +
> + rc = afu_attach(cfg, ctxi);
> + if (rc) {
> + pr_err("%s: Could not attach AFU rc %d\n", __func__, rc);
> + goto err3;
> + }
> +
> + /*
> + * No error paths after this point. Once the fd is installed it's
> + * visible to user space and can't be undone safely on this thread.
> + */
> + old_fd = ctxi->lfd;
> + ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
> + ctxi->lfd = fd;
> + ctxi->ctx = ctx;
> + ctxi->file = file;
> +
> + /*
> + * Put context back in table (note the reinit of the context list);
> + * we must first drop the context's mutex and then acquire it in
> + * order with the table/list mutex to avoid a deadlock - safe to do
> + * here because no one can find us at this moment in time.
> + */
> + mutex_unlock(&ctxi->mutex);
> + mutex_lock(&cfg->ctx_tbl_list_mutex);
> + mutex_lock(&ctxi->mutex);
> + list_del_init(&ctxi->list);
> + cfg->ctx_tbl[ctxid] = ctxi;
> + mutex_unlock(&cfg->ctx_tbl_list_mutex);
> + fd_install(fd, file);
> +
> + /* Release the original adapter fd and associated CXL resources */
> + sys_close(old_fd);
> +out:
> + pr_debug("%s: returning ctxid=%d fd=%d rc=%d\n",
> + __func__, ctxid, fd, rc);
> + return rc;
> +
> +err3:
> + cxl_stop_context(ctx);
> +err2:
> + fput(file);
> + put_unused_fd(fd);
> +err1:
> + cxl_release_context(ctx);
> + goto out;
> +}
> +
> +/**
> + * check_state() - checks and responds to the current adapter state
> + * @cfg: Internal structure associated with the host.
> + *
> + * This routine can block and should only be used on process context.
> + * Note that when waking up from waiting in limbo, the state is unknown
> + * and must be checked again before proceeding.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int check_state(struct cxlflash_cfg *cfg)
> +{
> + int rc = 0;
> +
> +retry:
> + switch (cfg->state) {
> + case STATE_LIMBO:
> + pr_debug("%s: Limbo, going to wait...\n", __func__);
> + rc = wait_event_interruptible(cfg->limbo_waitq,
> + cfg->state != STATE_LIMBO);
> + if (unlikely(rc))
> + goto out;
> + goto retry;
> + case STATE_FAILTERM:
> + pr_debug("%s: Failed/Terminating!\n", __func__);
> + rc = -ENODEV;
> + goto out;
> + default:
> + break;
> + }
> +out:
> + return rc;
> +}
> +
> +/**
> + * cxlflash_afu_recover() - initiates AFU recovery
> + * @sdev: SCSI device associated with LUN.
> + * @recover: Recover ioctl data structure.
> + *
> + * Only a single recovery is allowed at a time to avoid exhausting CXL
> + * resources (leading to recovery failure) in the event that we're up
> + * against the maximum number of contexts limit. For similar reasons,
> + * a context recovery is retried if there are multiple recoveries taking
> + * place at the same time and the failure was due to CXL services being
> + * unable to keep up.
> + *
> + * Because a user can detect an error condition before the kernel, it is
> + * quite possible for this routine to act as the kernel's EEH detection
> + * source (MMIO read of mbox_r). Because of this, there is a window of
> + * time where an EEH might have been detected but not yet 'serviced'
> + * (callback invoked, causing the device to enter limbo state). To avoid
> + * looping in this routine during that window, a 1 second sleep is in place
> + * between the time the MMIO failure is detected and the time a wait on the
> + * limbo wait queue is attempted via check_state().
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_afu_recover(struct scsi_device *sdev,
> + struct dk_cxlflash_recover_afu *recover)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct llun_info *lli = sdev->hostdata;
> + struct afu *afu = cfg->afu;
> + struct ctx_info *ctxi = NULL;
> + struct mutex *mutex = &cfg->ctx_recovery_mutex;
> + u64 ctxid = DECODE_CTXID(recover->context_id),
> + rctxid = recover->context_id;
> + long reg;
> + int lretry = 20; /* up to 2 seconds */
> + int rc = 0;
> +
> + atomic_inc(&cfg->recovery_threads);
> + rc = mutex_lock_interruptible(mutex);
> + if (rc)
> + goto out;
> +
> + pr_debug("%s: reason 0x%016llX rctxid=%016llX\n", __func__,
> + recover->reason, rctxid);
> +
> +retry:
> + /* Ensure that this process is attached to the context */
> + ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%llu)\n", __func__, ctxid);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + if (ctxi->err_recovery_active) {
> +retry_recover:
> + rc = recover_context(cfg, ctxi);
> + if (unlikely(rc)) {
> + pr_err("%s: Recovery failed for context %llu (rc=%d)\n",
> + __func__, ctxid, rc);
> + if ((rc == -ENODEV) &&
> + ((atomic_read(&cfg->recovery_threads) > 1) ||
> + (lretry--))) {
> + pr_debug("%s: Going to try again!\n", __func__);
> + mutex_unlock(mutex);
> + msleep(100);
> + rc = mutex_lock_interruptible(mutex);
> + if (rc)
> + goto out;
> + goto retry_recover;
> + }
> +
> + goto out;
> + }
> +
> + ctxi->err_recovery_active = false;
> + recover->context_id = ctxi->ctxid;
> + recover->adap_fd = ctxi->lfd;
> + recover->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
> + recover->hdr.return_flags |=
> + DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET;
> + goto out;
> + }
> +
> + /* Test if in error state */
> + reg = readq_be(&afu->ctrl_map->mbox_r);
> + if (reg == -1) {
> + pr_info("%s: MMIO read fail! Wait for recovery...\n", __func__);
> + mutex_unlock(&ctxi->mutex);
> + ctxi = NULL;
> + ssleep(1);
> + rc = check_state(cfg);
> + if (unlikely(rc))
> + goto out;
> + goto retry;
> + }
> +
> + pr_debug("%s: MMIO working, no recovery required!\n", __func__);
> +out:
> + if (likely(ctxi))
> + mutex_unlock(&ctxi->mutex);
> + mutex_unlock(mutex);
> + atomic_dec_if_positive(&cfg->recovery_threads);
> + return rc;
> +}
> +
> +/**
> + * process_sense() - evaluates and processes sense data
> + * @sdev: SCSI device associated with LUN.
> + * @verify: Verify ioctl data structure.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int process_sense(struct scsi_device *sdev,
> + struct dk_cxlflash_verify *verify)
> +{
> + struct llun_info *lli = sdev->hostdata;
> + struct glun_info *gli = lli->parent;
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + u64 prev_lba = gli->max_lba;
> + struct scsi_sense_hdr sshdr = { 0 };
> + int rc = 0;
> +
> + rc = scsi_normalize_sense((const u8 *)&verify->sense_data,
> + DK_CXLFLASH_VERIFY_SENSE_LEN, &sshdr);
> + if (!rc) {
> + pr_err("%s: Failed to normalize sense data!\n", __func__);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + switch (sshdr.sense_key) {
> + case NO_SENSE:
> + case RECOVERED_ERROR:
> + /* fall through */
> + case NOT_READY:
> + break;
> + case UNIT_ATTENTION:
> + switch (sshdr.asc) {
> + case 0x29: /* Power on Reset or Device Reset */
> + /* fall through */
> + case 0x2A: /* Device settings/capacity changed */
> + rc = read_cap16(sdev, lli);
> + if (rc) {
> + rc = -ENODEV;
> + break;
> + }
> + if (prev_lba != gli->max_lba)
> + pr_debug("%s: Capacity changed old=%lld "
> + "new=%lld\n", __func__, prev_lba,
> + gli->max_lba);
> + break;
> + case 0x3F: /* Report LUNs changed, Rescan. */
> + scsi_scan_host(cfg->host);
> + break;
> + default:
> + rc = -EIO;
> + break;
> + }
> + break;
> + default:
> + rc = -EIO;
> + break;
> + }
> +out:
> + pr_debug("%s: sense_key %x asc %x ascq %x rc %d\n", __func__,
> + sshdr.sense_key, sshdr.asc, sshdr.ascq, rc);
> + return rc;
> +}
> +
> +/**
> + * cxlflash_disk_verify() - verifies a LUN is the same and handle size changes
> + * @sdev: SCSI device associated with LUN.
> + * @verify: Verify ioctl data structure.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_disk_verify(struct scsi_device *sdev,
> + struct dk_cxlflash_verify *verify)
> +{
> + int rc = 0;
> + struct ctx_info *ctxi = NULL;
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct llun_info *lli = sdev->hostdata;
> + struct glun_info *gli = lli->parent;
> + struct sisl_rht_entry *rhte = NULL;
> + res_hndl_t rhndl = verify->rsrc_handle;
> + u64 ctxid = DECODE_CTXID(verify->context_id),
> + rctxid = verify->context_id;
> + u64 last_lba = 0;
> +
> + pr_debug("%s: ctxid=%llu rhndl=%016llX, hint=%016llX, flags=%016llX\n",
> + __func__, ctxid, verify->rsrc_handle, verify->hint,
> + verify->hdr.flags);
> +
> + ctxi = get_context(cfg, rctxid, lli, 0);
> + if (unlikely(!ctxi)) {
> + pr_err("%s: Bad context! (%llu)\n", __func__, ctxid);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + rhte = get_rhte(ctxi, rhndl, lli);
> + if (unlikely(!rhte)) {
> + pr_err("%s: Bad resource handle! (%d)\n", __func__, rhndl);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + /*
> + * Look at the hint/sense to see if it requires us to redrive
> + * inquiry (i.e. the Unit attention is due to the WWN changing).
> + */
> + if (verify->hint & DK_CXLFLASH_VERIFY_HINT_SENSE) {
> + rc = process_sense(sdev, verify);
> + if (unlikely(rc)) {
> + pr_err("%s: Failed to validate sense data! (%d)\n",
> + __func__, rc);
> + goto out;
> + }
> + }
> +
> + switch (gli->mode) {
> + case MODE_PHYSICAL:
> + last_lba = gli->max_lba;
> + break;
> + default:
> + WARN(1, "Unsupported LUN mode!");
> + }
> +
> + verify->last_lba = last_lba;
> +
> +out:
> + if (likely(ctxi))
> + mutex_unlock(&ctxi->mutex);
> + pr_debug("%s: returning rc=%d llba=%llX\n",
> + __func__, rc, verify->last_lba);
> + return rc;
> +}
> +
> +/**
> + * decode_ioctl() - translates an encoded ioctl to an easily identifiable string
> + * @cmd: The ioctl command to decode.
> + *
> + * Return: A string identifying the decoded ioctl.
> + */
> +static char *decode_ioctl(int cmd)
> +{
> + switch (cmd) {
> + case DK_CXLFLASH_ATTACH:
> + return __stringify_1(DK_CXLFLASH_ATTACH);
> + case DK_CXLFLASH_USER_DIRECT:
> + return __stringify_1(DK_CXLFLASH_USER_DIRECT);
> + case DK_CXLFLASH_RELEASE:
> + return __stringify_1(DK_CXLFLASH_RELEASE);
> + case DK_CXLFLASH_DETACH:
> + return __stringify_1(DK_CXLFLASH_DETACH);
> + case DK_CXLFLASH_VERIFY:
> + return __stringify_1(DK_CXLFLASH_VERIFY);
> + case DK_CXLFLASH_RECOVER_AFU:
> + return __stringify_1(DK_CXLFLASH_RECOVER_AFU);
> + case DK_CXLFLASH_MANAGE_LUN:
> + return __stringify_1(DK_CXLFLASH_MANAGE_LUN);
> + }
> +
> + return "UNKNOWN";
> +}
> +
> +/**
> + * cxlflash_disk_direct_open() - opens a direct (physical) disk
> + * @sdev: SCSI device associated with LUN.
> + * @arg: UDirect ioctl data structure.
> + *
> + * On successful return, the user is informed of the resource handle
> + * to be used to identify the direct lun and the size (in blocks) of
> + * the direct lun in last LBA format.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int cxlflash_disk_direct_open(struct scsi_device *sdev, void *arg)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct device *dev = &cfg->dev->dev;
> + struct afu *afu = cfg->afu;
> + struct llun_info *lli = sdev->hostdata;
> + struct glun_info *gli = lli->parent;
> +
> + struct dk_cxlflash_udirect *pphys = (struct dk_cxlflash_udirect *)arg;
> +
> + u64 ctxid = DECODE_CTXID(pphys->context_id),
> + rctxid = pphys->context_id;
> + u64 lun_size = 0;
> + u64 last_lba = 0;
> + u64 rsrc_handle = -1;
> + u32 port = CHAN2PORT(sdev->channel);
> +
> + int rc = 0;
> +
> + struct ctx_info *ctxi = NULL;
> + struct sisl_rht_entry *rhte = NULL;
> +
> + pr_debug("%s: ctxid=%llu ls=0x%llx\n", __func__, ctxid, lun_size);
> +
> + rc = cxlflash_lun_attach(gli, MODE_PHYSICAL);
> + if (unlikely(rc)) {
> + dev_err(dev, "%s: Failed to attach to LUN! (PHYSICAL)\n",

Is this going to spam the console from userspace? Same below.

> + __func__);
> + goto out;
> + }
> +
> + ctxi = get_context(cfg, rctxid, lli, 0);
> + if (unlikely(!ctxi)) {
> + dev_err(dev, "%s: Bad context! (%llu)\n", __func__, ctxid);
> + rc = -EINVAL;
> + goto err1;
> + }
> +
> + rhte = rhte_checkout(ctxi, lli);
> + if (unlikely(!rhte)) {
> + dev_err(dev, "%s: too many opens for this context\n", __func__);
> + rc = -EMFILE; /* too many opens */
> + goto err1;
> + }
> +
> + rsrc_handle = (rhte - ctxi->rht_start);
> +
> + rht_format1(rhte, lli->lun_id[sdev->channel], ctxi->rht_perms, port);
> + cxlflash_afu_sync(afu, ctxid, rsrc_handle, AFU_LW_SYNC);
> +
> + last_lba = gli->max_lba;
> + pphys->hdr.return_flags = 0;
> + pphys->last_lba = last_lba;
> + pphys->rsrc_handle = rsrc_handle;
> +
> +out:
> + if (likely(ctxi))
> + mutex_unlock(&ctxi->mutex);
> + pr_debug("%s: returning handle 0x%llx rc=%d llba %lld\n",
> + __func__, rsrc_handle, rc, last_lba);
> + return rc;
> +
> +err1:
> + cxlflash_lun_detach(gli);
> + goto out;
> +}
> +
> +/**
> + * ioctl_common() - common IOCTL handler for driver
> + * @sdev: SCSI device associated with LUN.
> + * @cmd: IOCTL command.
> + *
> + * Handles common fencing operations that are valid for multiple ioctls. Always
> + * allow through ioctls that are cleanup oriented in nature, even when operating
> + * in a failed/terminating state.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +static int ioctl_common(struct scsi_device *sdev, int cmd)
> +{
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct llun_info *lli = sdev->hostdata;
> + int rc = 0;
> +
> + if (unlikely(!lli)) {
> + pr_debug("%s: Unknown LUN\n", __func__);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + rc = check_state(cfg);
> + if (unlikely(rc) && (cfg->state == STATE_FAILTERM)) {
> + switch (cmd) {
> + case DK_CXLFLASH_RELEASE:
> + case DK_CXLFLASH_DETACH:
> + pr_debug("%s: Command override! (%d)\n", __func__, rc);
> + rc = 0;
> + break;
> + }
> + }
> +out:
> + return rc;
> +}
> +
> +/**
> + * cxlflash_ioctl() - IOCTL handler for driver
> + * @sdev: SCSI device associated with LUN.
> + * @cmd: IOCTL command.
> + * @arg: Userspace ioctl data structure.
> + *
> + * Return: 0 on success, -errno on failure
> + */
> +int cxlflash_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
> +{
> + typedef int (*sioctl) (struct scsi_device *, void *);
> +
> + struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
> + struct afu *afu = cfg->afu;
> + struct dk_cxlflash_hdr *hdr;
> + char buf[MAX_CXLFLASH_IOCTL_SZ];

why is buf not just a "union cxlflash_ioctls"?

> + size_t size = 0;
> + bool known_ioctl = false;
> + int idx;
> + int rc = 0;
> + struct Scsi_Host *shost = sdev->host;
> + sioctl do_ioctl = NULL;
> +
> + static const struct {
> + size_t size;
> + sioctl ioctl;
> + } ioctl_tbl[] = { /* NOTE: order matters here */
> + {sizeof(struct dk_cxlflash_attach), (sioctl)cxlflash_disk_attach},
> + {sizeof(struct dk_cxlflash_udirect), cxlflash_disk_direct_open},
> + {sizeof(struct dk_cxlflash_release), (sioctl)cxlflash_disk_release},
> + {sizeof(struct dk_cxlflash_detach), (sioctl)cxlflash_disk_detach},
> + {sizeof(struct dk_cxlflash_verify), (sioctl)cxlflash_disk_verify},
> + {sizeof(struct dk_cxlflash_recover_afu), (sioctl)cxlflash_afu_recover},
> + {sizeof(struct dk_cxlflash_manage_lun), (sioctl)cxlflash_manage_lun},
> + };
> +
> + /* Restrict command set to physical support only for internal LUN */
> + if (afu->internal_lun)
> + switch (cmd) {
> + case DK_CXLFLASH_RELEASE:
> + pr_err("%s: %s not supported for lun_mode=%d\n",
> + __func__, decode_ioctl(cmd), afu->internal_lun);
> + rc = -EINVAL;
> + goto cxlflash_ioctl_exit;
> + }
> +
> + switch (cmd) {
> + case DK_CXLFLASH_ATTACH:
> + case DK_CXLFLASH_USER_DIRECT:
> + case DK_CXLFLASH_RELEASE:
> + case DK_CXLFLASH_DETACH:
> + case DK_CXLFLASH_VERIFY:
> + case DK_CXLFLASH_RECOVER_AFU:
> + pr_debug("%s: %s (%08X) on dev(%d/%d/%d/%llu)\n", __func__,
> + decode_ioctl(cmd), cmd, shost->host_no, sdev->channel,
> + sdev->id, sdev->lun);
> + rc = ioctl_common(sdev, cmd);
> + if (unlikely(rc))
> + goto cxlflash_ioctl_exit;
> +
> + /* fall through */
> +
> + case DK_CXLFLASH_MANAGE_LUN:
> + known_ioctl = true;
> + idx = _IOC_NR(cmd) - _IOC_NR(DK_CXLFLASH_ATTACH);
> + size = ioctl_tbl[idx].size;
> + do_ioctl = ioctl_tbl[idx].ioctl;
> +
> + if (likely(do_ioctl))
> + break;
> +
> + /* fall through */
> + default:
> + rc = -EINVAL;
> + goto cxlflash_ioctl_exit;
> + }
> +
> + if (unlikely(copy_from_user(&buf, arg, size))) {
> + pr_err("%s: copy_from_user() fail! "
> + "size=%lu cmd=%d (%s) arg=%p\n",
> + __func__, size, cmd, decode_ioctl(cmd), arg);
> + rc = -EFAULT;
> + goto cxlflash_ioctl_exit;
> + }
> +
> + hdr = (struct dk_cxlflash_hdr *)&buf;
> + if (hdr->version != 0) {
> + pr_err("%s: Version %u not supported for %s\n",
> + __func__, hdr->version, decode_ioctl(cmd));
> + rc = -EINVAL;
> + goto cxlflash_ioctl_exit;
> + }

Do you advertise this version anywhere? Users just have to call it and fail?

You should check hdr->flags are zero incase some new userspace tries to set
them. Same for hdr->rsvd.

Also, can you do these checks earlier. It seems you've already done a bunch of
stuff before here.

> +
> + rc = do_ioctl(sdev, (void *)&buf);
> + if (likely(!rc))
> + if (unlikely(copy_to_user(arg, &buf, size))) {
> + pr_err("%s: copy_to_user() fail! "
> + "size=%lu cmd=%d (%s) arg=%p\n",
> + __func__, size, cmd, decode_ioctl(cmd), arg);
> + rc = -EFAULT;
> + }
> +
> + /* fall through to exit */
> +
> +cxlflash_ioctl_exit:
> + if (unlikely(rc && known_ioctl))
> + pr_err("%s: ioctl %s (%08X) on dev(%d/%d/%d/%llu) "
> + "returned rc %d\n", __func__,
> + decode_ioctl(cmd), cmd, shost->host_no,
> + sdev->channel, sdev->id, sdev->lun, rc);
> + else
> + pr_debug("%s: ioctl %s (%08X) on dev(%d/%d/%d/%llu) "
> + "returned rc %d\n", __func__, decode_ioctl(cmd),
> + cmd, shost->host_no, sdev->channel, sdev->id,
> + sdev->lun, rc);
> + return rc;
> +}
> +

git am complains about this trailing new line.

> diff --git a/drivers/scsi/cxlflash/superpipe.h b/drivers/scsi/cxlflash/superpipe.h
> new file mode 100644
> index 0000000..030892b
> --- /dev/null
> +++ b/drivers/scsi/cxlflash/superpipe.h
> @@ -0,0 +1,127 @@
> +/*
> + * CXL Flash Device Driver
> + *
> + * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
> + * Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
> + *
> + * Copyright (C) 2015 IBM Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#ifndef _CXLFLASH_SUPERPIPE_H
> +#define _CXLFLASH_SUPERPIPE_H
> +
> +/*
> + * Terminology: use afu (and not adapter) to refer to the HW.
> + * Adapter is the entire slot and includes PSL out of which
> + * only the AFU is visible to user space.
> + */
> +
> +/* Chunk size parms: note sislite minimum chunk size is
> + 0x10000 LBAs corresponding to a NMASK or 16.
> +*/
> +#define MC_CHUNK_SIZE (1 << MC_RHT_NMASK) /* in LBAs, see mclient.h */
> +
> +#define MC_DISCOVERY_TIMEOUT 5 /* 5 secs */
> +
> +#define CHAN2PORT(_x) ((_x) + 1)
> +
> +enum lun_mode {
> + MODE_NONE = 0,
> + MODE_PHYSICAL
> +};
> +
> +/* Global (entire driver, spans adapters) lun_info structure */
> +struct glun_info {
> + u64 max_lba; /* from read cap(16) */
> + u32 blk_len; /* from read cap(16) */
> + enum lun_mode mode; /* NONE, PHYSICAL */
> + int users; /* Number of users w/ references to LUN */
> +
> + u8 wwid[16];
> +
> + spinlock_t slock;
> +
> + struct list_head list;
> +};
> +
> +/* Local (per-adapter) lun_info structure */
> +struct llun_info {
> + u64 lun_id[CXLFLASH_NUM_FC_PORTS]; /* from REPORT_LUNS */
> + u32 lun_index; /* Index in the lun table */
> + u32 host_no; /* host_no from Scsi_host */
> + u32 port_sel; /* What port to use for this LUN */
> + bool newly_created; /* Whether the LUN was just discovered */
> +
> + u8 wwid[16]; /* Keep a duplicate copy here? */
> +
> + struct glun_info *parent; /* Pointer to entry in global lun structure */
> + struct scsi_device *sdev;
> + struct list_head list;
> +};
> +
> +struct lun_access {
> + struct llun_info *lli;
> + struct scsi_device *sdev;
> + struct list_head list;
> +};
> +
> +enum ctx_ctrl {
> + CTX_CTRL_CLONE = (1 << 1),
> + CTX_CTRL_ERR = (1 << 2),
> + CTX_CTRL_ERR_FALLBACK = (1 << 3),
> + CTX_CTRL_NOPID = (1 << 4),
> + CTX_CTRL_FILE = (1 << 5)
> +};
> +
> +#define ENCODE_CTXID(_ctx, _id) (((((u64)_ctx) & 0xFFFFFFFF0) << 28) | _id)
> +#define DECODE_CTXID(_val) (_val & 0xFFFFFFFF)
> +
> +struct ctx_info {
> + struct sisl_ctrl_map *ctrl_map; /* initialized at startup */
> + struct sisl_rht_entry *rht_start; /* 1 page (req'd for alignment),
> + alloc/free on attach/detach */
> + u32 rht_out; /* Number of checked out RHT entries */
> + u32 rht_perms; /* User-defined permissions for RHT entries */
> + struct llun_info **rht_lun; /* Mapping of RHT entries to LUNs */
> +
> + struct cxl_ioctl_start_work work;
> + u64 ctxid;
> + int lfd;
> + pid_t pid;
> + bool unavail;
> + bool err_recovery_active;
> + struct mutex mutex; /* Context protection */
> + struct cxl_context *ctx;
> + struct list_head luns; /* LUNs attached to this context */
> + const struct vm_operations_struct *cxl_mmap_vmops;
> + struct file *file;
> + struct list_head list; /* Link contexts in error recovery */
> +};
> +
> +struct cxlflash_global {
> + spinlock_t slock;
> + struct list_head gluns;/* list of glun_info structs */
> + struct page *err_page; /* One page of all 0xF for error notification */
> +};
> +
> +int cxlflash_disk_release(struct scsi_device *, struct dk_cxlflash_release *);
> +int _cxlflash_disk_release(struct scsi_device *, struct ctx_info *,
> + struct dk_cxlflash_release *);
> +
> +int cxlflash_lun_attach(struct glun_info *, enum lun_mode);
> +void cxlflash_lun_detach(struct glun_info *);
> +
> +struct ctx_info *get_context(struct cxlflash_cfg *, u64, void *, enum ctx_ctrl);
> +
> +struct sisl_rht_entry *get_rhte(struct ctx_info *, res_hndl_t,
> + struct llun_info *);
> +
> +struct sisl_rht_entry *rhte_checkout(struct ctx_info *, struct llun_info *);
> +void rhte_checkin(struct ctx_info *, struct sisl_rht_entry *);
> +
> +#endif /* ifndef _CXLFLASH_SUPERPIPE_H */
> diff --git a/include/uapi/scsi/Kbuild b/include/uapi/scsi/Kbuild
> index 75746d5..d791e0a 100644
> --- a/include/uapi/scsi/Kbuild
> +++ b/include/uapi/scsi/Kbuild
> @@ -3,3 +3,4 @@ header-y += fc/
> header-y += scsi_bsg_fc.h
> header-y += scsi_netlink.h
> header-y += scsi_netlink_fc.h
> +header-y += cxlflash_ioctl.h
> diff --git a/include/uapi/scsi/cxlflash_ioctl.h b/include/uapi/scsi/cxlflash_ioctl.h
> new file mode 100644
> index 0000000..f11bdcf
> --- /dev/null
> +++ b/include/uapi/scsi/cxlflash_ioctl.h
> @@ -0,0 +1,139 @@
> +/*
> + * CXL Flash Device Driver
> + *
> + * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
> + * Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
> + *
> + * Copyright (C) 2015 IBM Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#ifndef _CXLFLASH_IOCTL_H
> +#define _CXLFLASH_IOCTL_H
> +
> +#include <linux/types.h>
> +
> +/*
> + * Structure and flag definitions CXL Flash superpipe ioctls
> + */
> +
> +struct dk_cxlflash_hdr {
> + __u16 version; /* Version data */
> + __u16 rsvd[3]; /* Reserved for future use */
> + __u64 flags; /* Input flags */
> + __u64 return_flags; /* Returned flags */

> +};
> +
> +/*
> + * Notes:
> + * -----
> + * The 'context_id' field of all ioctl structures contains the context
> + * identifier for a context in the lower 32-bits (upper 32-bits are not
> + * to be used when identifying a context to the AFU). That said, the value
> + * in its entirety (all 64-bits) is to be treated as an opaque cookie and
> + * should be presented as such when issuing ioctls.
> + *
> + * For DK_CXLFLASH_ATTACH ioctl, user specifies read/write access
> + * permissions via the O_RDONLY, O_WRONLY, and O_RDWR flags defined in
> + * the fcntl.h header file.
> + */
> +#define DK_CXLFLASH_ATTACH_REUSE_CONTEXT 0x8000000000000000ULL
> +
> +struct dk_cxlflash_attach {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 num_interrupts; /* Requested number of interrupts */
> + __u64 context_id; /* Returned context */
> + __u64 mmio_size; /* Returned size of MMIO area */
> + __u64 block_size; /* Returned block size, in bytes */
> + __u64 adap_fd; /* Returned adapter file descriptor */
> + __u64 last_lba; /* Returned last LBA on the device */
> + __u64 max_xfer; /* Returned max transfer size, blocks */
> + __u64 reserved[8]; /* Reserved for future use */

> +};
> +
> +struct dk_cxlflash_detach {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 context_id; /* Context to detach */
> + __u64 reserved[8]; /* Reserved for future use */
> +};
> +
> +struct dk_cxlflash_udirect {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 context_id; /* Context to own physical resources */
> + __u64 rsrc_handle; /* Returned resource handle */
> + __u64 last_lba; /* Returned last LBA on the device */
> + __u64 reserved[8]; /* Reserved for future use */
> +};
> +
> +struct dk_cxlflash_release {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 context_id; /* Context owning resources */
> + __u64 rsrc_handle; /* Resource handle to release */
> + __u64 reserved[8]; /* Reserved for future use */
> +};
> +
> +#define DK_CXLFLASH_VERIFY_SENSE_LEN 18
> +#define DK_CXLFLASH_VERIFY_HINT_SENSE 0x8000000000000000ULL
> +
> +struct dk_cxlflash_verify {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 context_id; /* Context owning resources to verify */
> + __u64 rsrc_handle; /* Resource handle of LUN */
> + __u64 hint; /* Reasons for verify */
> + __u64 last_lba; /* Returned last LBA of device */
> + __u8 sense_data[DK_CXLFLASH_VERIFY_SENSE_LEN]; /* SCSI sense data */
> + __u8 pad[6]; /* Pad to next 8-byte boundary */
> + __u64 reserved[8]; /* Reserved for future use */
> +};
> +
> +#define DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET 0x8000000000000000ULL
> +
> +struct dk_cxlflash_recover_afu {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u64 reason; /* Reason for recovery request */
> + __u64 context_id; /* Context to recover / updated ID */
> + __u64 mmio_size; /* Returned size of MMIO area */
> + __u64 adap_fd; /* Returned adapter file descriptor */
> + __u64 reserved[8]; /* Reserved for future use */
> +};
> +
> +#define DK_CXLFLASH_MANAGE_LUN_WWID_LEN 16
> +#define DK_CXLFLASH_MANAGE_LUN_ENABLE_SUPERPIPE 0x8000000000000000ULL
> +#define DK_CXLFLASH_MANAGE_LUN_DISABLE_SUPERPIPE 0x4000000000000000ULL
> +#define DK_CXLFLASH_MANAGE_LUN_ALL_PORTS_ACCESSIBLE 0x2000000000000000ULL
> +
> +struct dk_cxlflash_manage_lun {
> + struct dk_cxlflash_hdr hdr; /* Common fields */
> + __u8 wwid[DK_CXLFLASH_MANAGE_LUN_WWID_LEN]; /* Page83 WWID, NAA-6 */
> + __u64 reserved[8]; /* Rsvd, future use */
> +};
> +
> +union cxlflash_ioctls {
> + struct dk_cxlflash_attach attach;
> + struct dk_cxlflash_detach detach;
> + struct dk_cxlflash_udirect udirect;
> + struct dk_cxlflash_release release;
> + struct dk_cxlflash_verify verify;
> + struct dk_cxlflash_recover_afu recover_afu;
> + struct dk_cxlflash_manage_lun manage_lun;
> +};
> +
> +#define MAX_CXLFLASH_IOCTL_SZ (sizeof(union cxlflash_ioctls))
> +
> +
> +#define CXL_MAGIC 0xCA
> +#define CXL_IOWR(_n, _s) _IOWR(CXL_MAGIC, _n, struct _s)
> +
> +#define DK_CXLFLASH_ATTACH CXL_IOWR(0x80, dk_cxlflash_attach)
> +#define DK_CXLFLASH_USER_DIRECT CXL_IOWR(0x81, dk_cxlflash_udirect)
> +#define DK_CXLFLASH_RELEASE CXL_IOWR(0x84, dk_cxlflash_release)
> +#define DK_CXLFLASH_DETACH CXL_IOWR(0x85, dk_cxlflash_detach)
> +#define DK_CXLFLASH_VERIFY CXL_IOWR(0x86, dk_cxlflash_verify)
> +#define DK_CXLFLASH_RECOVER_AFU CXL_IOWR(0x88, dk_cxlflash_recover_afu)
> +#define DK_CXLFLASH_MANAGE_LUN CXL_IOWR(0x89, dk_cxlflash_manage_lun)

I'm not sure I'd leave these sparse. What happens if the vlun patches don't
get in?

> +
> +#endif /* ifndef _CXLFLASH_IOCTL_H */