Re: [PATCH V3 XRT Alveo 05/18] fpga: xrt: group platform driver

Tom Rix
2021-02-22T18:53:33Z

On 2/17/21 10:40 PM, Lizhi Hou wrote:
> group driver that manages life cycle of a bunch of leaf driver instances
> and bridges them with root.
>
> Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
> Signed-off-by: Max Zhen <max.zhen@xilinx.com>
> Signed-off-by: Lizhi Hou <lizhih@xilinx.com>
> ---
> drivers/fpga/xrt/include/group.h | 27 ++++
> drivers/fpga/xrt/lib/group.c | 265 +++++++++++++++++++++++++++++++
> 2 files changed, 292 insertions(+)
> create mode 100644 drivers/fpga/xrt/include/group.h
> create mode 100644 drivers/fpga/xrt/lib/group.c
>
> diff --git a/drivers/fpga/xrt/include/group.h b/drivers/fpga/xrt/include/group.h
> new file mode 100644
> index 000000000000..1874cdd5120d
> --- /dev/null
> +++ b/drivers/fpga/xrt/include/group.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Header file for Xilinx Runtime (XRT) driver
A bit too generic, please add a description or remove.
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + * Cheng Zhen <maxz@xilinx.com>
> + */
> +
> +#ifndef _XRT_GROUP_H_
> +#define _XRT_GROUP_H_
> +
> +#include "xleaf.h"
This is patch 6, consider comments on patch 4.
> +
> +/*
> + * Group driver IOCTL calls.

Are these really ioctl calls?

Seems more like messages between nodes in a tree.

Consider changing to better jagon, maybe ioctl -> msg

> + */
> +enum xrt_group_ioctl_cmd {
> + XRT_GROUP_GET_LEAF = XRT_XLEAF_CUSTOM_BASE, /* See comments in xleaf.h */
XRT_LEAF_CUSTOM_BASE is a #define, while these are enums. To be consistent, the XRT_LEAF_CUSTOM_BASE should be an enum in xleaf, you can initialize it to 64 there.
> + XRT_GROUP_PUT_LEAF,
> + XRT_GROUP_INIT_CHILDREN,
> + XRT_GROUP_FINI_CHILDREN,
> + XRT_GROUP_TRIGGER_EVENT,
> +};
> +
> +#endif /* _XRT_GROUP_H_ */
> diff --git a/drivers/fpga/xrt/lib/group.c b/drivers/fpga/xrt/lib/group.c
> new file mode 100644
> index 000000000000..6ba56eea479b
> --- /dev/null
> +++ b/drivers/fpga/xrt/lib/group.c
> @@ -0,0 +1,265 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Xilinx Alveo FPGA Group Driver
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + * Cheng Zhen <maxz@xilinx.com>
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include "xleaf.h"
> +#include "subdev_pool.h"
> +#include "group.h"
> +#include "metadata.h"
> +#include "main.h"
> +
> +#define XRT_GRP "xrt_group"
> +
> +struct xrt_group {
> + struct platform_device *pdev;
> + struct xrt_subdev_pool leaves;
> + bool leaves_created;
> + struct mutex lock; /* lock for group */
> +};
> +
> +static int xrt_grp_root_cb(struct device *dev, void *parg,
> + u32 cmd, void *arg)
could 'cmd' be some enum type ?
> +{
> + int rc;
> + struct platform_device *pdev =
> + container_of(dev, struct platform_device, dev);
> + struct xrt_group *xg = (struct xrt_group *)parg;
> +
> + switch (cmd) {
> + case XRT_ROOT_GET_LEAF_HOLDERS: {
> + struct xrt_root_ioctl_get_holders *holders =
> + (struct xrt_root_ioctl_get_holders *)arg;
> + rc = xrt_subdev_pool_get_holders(&xg->leaves,
> + holders->xpigh_pdev,
> + holders->xpigh_holder_buf,
> + holders->xpigh_holder_buf_len);
> + break;
> + }
> + default:
> + /* Forward parent call to root. */
> + rc = xrt_subdev_root_request(pdev, cmd, arg);
> + break;
> + }
> +
> + return rc;
> +}
> +
> +static int xrt_grp_create_leaves(struct xrt_group *xg)
> +{
> + struct xrt_subdev_platdata *pdata = DEV_PDATA(xg->pdev);
> + enum xrt_subdev_id did;
> + struct xrt_subdev_endpoints *eps = NULL;
> + int ep_count = 0, i, ret = 0, failed = 0;
> + unsigned long mlen;
> + char *dtb, *grp_dtb = NULL;
> + const char *ep_name;
> +
> + mutex_lock(&xg->lock);
> +
> + if (xg->leaves_created) {
> + mutex_unlock(&xg->lock);
This happens should be programming error, so print out some error message
> + return -EEXIST;
> + }
> +
> + xrt_info(xg->pdev, "bringing up leaves...");
> +
> + /* Create all leaves based on dtb. */
> + if (!pdata)
> + goto bail;
move to above the lock and fail with something like -EINVAL
> +
> + mlen = xrt_md_size(DEV(xg->pdev), pdata->xsp_dtb);
> + if (mlen == XRT_MD_INVALID_LENGTH) {
> + xrt_err(xg->pdev, "invalid dtb, len %ld", mlen);
> + goto bail;
> + }
> +
> + grp_dtb = vmalloc(mlen);
> + if (!grp_dtb)
> + goto bail;
failed is only set in the loop. This is an unreported -ENOMEM
> +
> + memcpy(grp_dtb, pdata->xsp_dtb, mlen);
> + for (did = 0; did < XRT_SUBDEV_NUM;) {
why isn't the did incremented ?
> + eps = eps ? eps + 1 : xrt_drv_get_endpoints(did);

this assumes the enpoints are in an array and accessed serially.

this is fragile.

convert to using just the xrt_drv_get_endpoints() call

> + if (!eps || !eps->xse_names) {
> + did++;
> + eps = NULL;
> + continue;
> + }
> + ret = xrt_md_create(DEV(xg->pdev), &dtb);
> + if (ret) {
> + xrt_err(xg->pdev, "create md failed, drv %s",
> + xrt_drv_name(did));
> + failed++;
failed but no cleanup of earier successes
> + continue;
> + }
> + for (i = 0; eps->xse_names[i].ep_name ||

this assumes that xse_names[] always has a guard.

why not use xse_min_ep ?

> + eps->xse_names[i].regmap_name; i++) {
> + ep_name = (char *)eps->xse_names[i].ep_name;
> + if (!ep_name) {
> + xrt_md_get_compatible_endpoint(DEV(xg->pdev),
> + grp_dtb,
> + eps->xse_names[i].regmap_name,
> + &ep_name);
> + }
> + if (!ep_name)
> + continue;
> +
> + ret = xrt_md_copy_endpoint(DEV(xg->pdev),
> + dtb, grp_dtb, ep_name,
> + (char *)eps->xse_names[i].regmap_name,
> + NULL);
> + if (ret)
> + continue;
> + xrt_md_del_endpoint(DEV(xg->pdev), grp_dtb, ep_name,
> + (char *)eps->xse_names[i].regmap_name);
> + ep_count++;
> + }
> + if (ep_count >= eps->xse_min_ep) {
This only happens if all additions are successful.
> + ret = xrt_subdev_pool_add(&xg->leaves, did,
> + xrt_grp_root_cb, xg, dtb);
> + eps = NULL;
> + if (ret < 0) {
> + failed++;
> + xrt_err(xg->pdev, "failed to create %s: %d",
> + xrt_drv_name(did), ret);
> + }
> + } else if (ep_count > 0) {
> + xrt_md_copy_all_endpoints(DEV(xg->pdev), grp_dtb, dtb);
> + }
> + vfree(dtb);
> + ep_count = 0;
> + }
> +
> + xg->leaves_created = true;
This is true even if some failed ?
> +
> +bail:
> + vfree(grp_dtb);
> + mutex_unlock(&xg->lock);
> +
> + return failed == 0 ? 0 : -ECHILD;
> +}
> +
> +static void xrt_grp_remove_leaves(struct xrt_group *xg)
> +{
> + mutex_lock(&xg->lock);
> +
> + if (!xg->leaves_created) {
> + mutex_unlock(&xg->lock);
> + return;
> + }
> +
> + xrt_info(xg->pdev, "tearing down leaves...");
> + xrt_subdev_pool_fini(&xg->leaves);
partial failure above and the subdev_pool is not created ?
> + xg->leaves_created = false;
> +
> + mutex_unlock(&xg->lock);
> +}
> +
> +static int xrt_grp_probe(struct platform_device *pdev)
> +{
> + struct xrt_group *xg;
> +
> + xrt_info(pdev, "probing...");
> +
> + xg = devm_kzalloc(&pdev->dev, sizeof(*xg), GFP_KERNEL);
> + if (!xg)
> + return -ENOMEM;
> +
> + xg->pdev = pdev;
> + mutex_init(&xg->lock);
> + xrt_subdev_pool_init(DEV(pdev), &xg->leaves);
> + platform_set_drvdata(pdev, xg);
> +
> + return 0;
> +}
> +
> +static int xrt_grp_remove(struct platform_device *pdev)
> +{
> + struct xrt_group *xg = platform_get_drvdata(pdev);
> +
> + xrt_info(pdev, "leaving...");
> + xrt_grp_remove_leaves(xg);

lock ?

Tom

> + return 0;
> +}
> +
> +static int xrt_grp_ioctl(struct platform_device *pdev, u32 cmd, void *arg)
> +{
> + int rc = 0;
> + struct xrt_group *xg = platform_get_drvdata(pdev);
> +
> + switch (cmd) {
> + case XRT_XLEAF_EVENT:
> + /* Simply forward to every child. */
> + xrt_subdev_pool_handle_event(&xg->leaves,
> + (struct xrt_event *)arg);
> + break;
> + case XRT_GROUP_GET_LEAF: {
> + struct xrt_root_ioctl_get_leaf *get_leaf =
> + (struct xrt_root_ioctl_get_leaf *)arg;
> +
> + rc = xrt_subdev_pool_get(&xg->leaves, get_leaf->xpigl_match_cb,
> + get_leaf->xpigl_match_arg,
> + DEV(get_leaf->xpigl_pdev),
> + &get_leaf->xpigl_leaf);
> + break;
> + }
> + case XRT_GROUP_PUT_LEAF: {
> + struct xrt_root_ioctl_put_leaf *put_leaf =
> + (struct xrt_root_ioctl_put_leaf *)arg;
> +
> + rc = xrt_subdev_pool_put(&xg->leaves, put_leaf->xpipl_leaf,
> + DEV(put_leaf->xpipl_pdev));
> + break;
> + }
> + case XRT_GROUP_INIT_CHILDREN:
> + rc = xrt_grp_create_leaves(xg);
> + break;
> + case XRT_GROUP_FINI_CHILDREN:
> + xrt_grp_remove_leaves(xg);
> + break;
> + case XRT_GROUP_TRIGGER_EVENT:
> + xrt_subdev_pool_trigger_event(&xg->leaves, (enum xrt_events)(uintptr_t)arg);
> + break;
> + default:
> + xrt_err(pdev, "unknown IOCTL cmd %d", cmd);
> + rc = -EINVAL;
> + break;
> + }
> + return rc;
> +}
> +
> +static struct xrt_subdev_drvdata xrt_grp_data = {
> + .xsd_dev_ops = {
> + .xsd_ioctl = xrt_grp_ioctl,
> + },
> +};
> +
> +static const struct platform_device_id xrt_grp_id_table[] = {
> + { XRT_GRP, (kernel_ulong_t)&xrt_grp_data },
> + { },
> +};
> +
> +static struct platform_driver xrt_group_driver = {
> + .driver = {
> + .name = XRT_GRP,
> + },
> + .probe = xrt_grp_probe,
> + .remove = xrt_grp_remove,
> + .id_table = xrt_grp_id_table,
> +};
> +
> +void group_leaf_init_fini(bool init)
> +{
> + if (init)
> + xleaf_register_driver(XRT_SUBDEV_GRP, &xrt_group_driver, NULL);
> + else
> + xleaf_unregister_driver(XRT_SUBDEV_GRP);
> +}