[PATCH 31/42] docs: scsi: convert scsi_mid_low_api.txt to ReST

Mauro Carvalho Chehab
2020-03-02T08:16:36Z

Documentation/scsi/scsi_eh.rst | 2 +-
...i_mid_low_api.txt => scsi_mid_low_api.rst} | 1730 +++++++++--------
scripts/documentation-file-ref-check | 2 +-
4 files changed, 895 insertions(+), 840 deletions(-)
rename Documentation/scsi/{scsi_mid_low_api.txt => scsi_mid_low_api.rst} (39%)

diff --git a/Documentation/scsi/index.rst b/Documentation/scsi/index.rst
index 119280f26da6..48337be1c3f1 100644
--- a/Documentation/scsi/index.rst
+++ b/Documentation/scsi/index.rst
@@ -35,5 +35,6 @@ Linux SCSI Subsystem
scsi_eh
scsi_fc_transport
scsi-generic
+ scsi_mid_low_api

scsi_transport_srp/figures
diff --git a/Documentation/scsi/scsi_eh.rst b/Documentation/scsi/scsi_eh.rst
index 341f22f35056..7d78c2475615 100644
--- a/Documentation/scsi/scsi_eh.rst
+++ b/Documentation/scsi/scsi_eh.rst
@@ -5,7 +5,7 @@ SCSI EH
=======

This document describes SCSI midlayer error handling infrastructure.
-Please refer to Documentation/scsi/scsi_mid_low_api.txt for more
+Please refer to Documentation/scsi/scsi_mid_low_api.rst for more
information regarding SCSI midlayer.

.. TABLE OF CONTENTS
diff --git a/Documentation/scsi/scsi_mid_low_api.txt b/Documentation/scsi/scsi_mid_low_api.rst
similarity index 39%
rename from Documentation/scsi/scsi_mid_low_api.txt
rename to Documentation/scsi/scsi_mid_low_api.rst
index 2a4be1c3e6db..37ee63b147e9 100644
--- a/Documentation/scsi/scsi_mid_low_api.txt
+++ b/Documentation/scsi/scsi_mid_low_api.rst
@@ -1,11 +1,13 @@
- Linux Kernel 2.6 series
- SCSI mid_level - lower_level driver interface
- =============================================
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================================
+SCSI mid_level - lower_level driver interface
+=============================================

Introduction
============
This document outlines the interface between the Linux SCSI mid level and
-SCSI lower level drivers. Lower level drivers (LLDs) are variously called
+SCSI lower level drivers. Lower level drivers (LLDs) are variously called
host bus adapter (HBA) drivers and host drivers (HD). A "host" in this
context is a bridge between a computer IO bus (e.g. PCI or ISA) and a
single SCSI initiator port on a SCSI transport. An "initiator" port
@@ -24,8 +26,8 @@ directory).
For example, the aic7xxx LLD controls Adaptec SCSI parallel interface
(SPI) controllers based on that company's 7xxx chip series. The aic7xxx
LLD can be built into the kernel or loaded as a module. There can only be
-one aic7xxx LLD running in a Linux system but it may be controlling many
-HBAs. These HBAs might be either on PCI daughter-boards or built into
+one aic7xxx LLD running in a Linux system but it may be controlling many
+HBAs. These HBAs might be either on PCI daughter-boards or built into
the motherboard (or both). Some aic7xxx based HBAs are dual controllers
and thus represent two hosts. Like most modern HBAs, each aic7xxx host
has its own PCI device address. [The one-to-one correspondence between
@@ -39,20 +41,20 @@ This version of the document roughly matches linux kernel version 2.6.8 .

Documentation
=============
-There is a SCSI documentation directory within the kernel source tree,
+There is a SCSI documentation directory within the kernel source tree,
typically Documentation/scsi . Most documents are in plain
-(i.e. ASCII) text. This file is named scsi_mid_low_api.txt and can be
+(i.e. ASCII) text. This file is named scsi_mid_low_api.txt and can be
found in that directory. A more recent copy of this document may be found
-at http://web.archive.org/web/20070107183357rn_1/sg.torque.net/scsi/.
+at http://web.archive.org/web/20070107183357rn_1/sg.torque.net/scsi/.
Many LLDs are documented there (e.g. aic7xxx.txt). The SCSI mid-level is
-briefly described in scsi.txt which contains a url to a document
-describing the SCSI subsystem in the lk 2.4 series. Two upper level
-drivers have documents in that directory: st.txt (SCSI tape driver) and
+briefly described in scsi.txt which contains a url to a document
+describing the SCSI subsystem in the lk 2.4 series. Two upper level
+drivers have documents in that directory: st.txt (SCSI tape driver) and
scsi-generic.txt (for the sg driver).

Some documentation (or urls) for LLDs may be found in the C source code
or in the same directory as the C source code. For example to find a url
-about the USB mass storage driver see the
+about the USB mass storage driver see the
/usr/src/linux/drivers/usb/storage directory.

Driver structure
@@ -62,7 +64,7 @@ the drivers/scsi directory. For example, a driver called "xyz" has a header
file "xyz.h" and a source file "xyz.c". [Actually there is no good reason
why this couldn't all be in one file; the header file is superfluous.] Some
drivers that have been ported to several operating systems have more than
-two files. For example the aic7xxx driver has separate files for generic
+two files. For example the aic7xxx driver has separate files for generic
and OS-specific code (e.g. FreeBSD and Linux). Such drivers tend to have
their own directory under the drivers/scsi directory.

@@ -80,10 +82,11 @@ to be hot plugged (and unplugged) during the lifetime of the LLD and will
be referred to as the "hotplug" initialization model. The newer model is
preferred as it can handle both traditional SCSI equipment that is
permanently connected as well as modern "SCSI" devices (e.g. USB or
-IEEE 1394 connected digital cameras) that are hotplugged. Both
+IEEE 1394 connected digital cameras) that are hotplugged. Both
initialization models are discussed in the following sections.

An LLD interfaces to the SCSI subsystem several ways:
+
a) directly invoking functions supplied by the mid level
b) passing a set of function pointers to a registration function
supplied by the mid level. The mid level will then invoke these
@@ -98,11 +101,11 @@ supplied functions" below.
Those functions in group b) are listed in a section entitled "Interface
functions" below. Their function pointers are placed in the members of
"struct scsi_host_template", an instance of which is passed to
-scsi_host_alloc() ** . Those interface functions that the LLD does not
-wish to supply should have NULL placed in the corresponding member of
-struct scsi_host_template. Defining an instance of struct
+scsi_host_alloc() [#]_. Those interface functions that the LLD does not
+wish to supply should have NULL placed in the corresponding member of
+struct scsi_host_template. Defining an instance of struct
scsi_host_template at file scope will cause NULL to be placed in function
- pointer members not explicitly initialized.
+pointer members not explicitly initialized.

Those usages in group c) should be handled with care, especially in a
"hotplug" environment. LLDs should be aware of the lifetime of instances
@@ -110,11 +113,11 @@ that are shared with the mid level and other layers.

All functions defined within an LLD and all data defined at file scope
should be static. For example the slave_alloc() function in an LLD
-called "xxx" could be defined as
-"static int xxx_slave_alloc(struct scsi_device * sdev) { /* code */ }"
+called "xxx" could be defined as
+``static int xxx_slave_alloc(struct scsi_device * sdev) { /* code */ }``

-** the scsi_host_alloc() function is a replacement for the rather vaguely
-named scsi_register() function in most situations.
+.. [#] the scsi_host_alloc() function is a replacement for the rather vaguely
+ named scsi_register() function in most situations.

Hotplug initialization model
@@ -136,48 +139,47 @@ aware of an LLD when that LLD registers its first HBA.

At some later time, the LLD becomes aware of an HBA and what follows
is a typical sequence of calls between the LLD and the mid level.
-This example shows the mid level scanning the newly introduced HBA for 3
-scsi devices of which only the first 2 respond:
+This example shows the mid level scanning the newly introduced HBA for 3
+scsi devices of which only the first 2 respond::

- HBA PROBE: assume 2 SCSI devices found in scan
-LLD mid level LLD
-===-------------------=========--------------------===------
-scsi_host_alloc() -->
-scsi_add_host() ---->
-scsi_scan_host() -------+
- |
- slave_alloc()
- slave_configure() --> scsi_change_queue_depth()
- |
- slave_alloc()
- slave_configure()
- |
- slave_alloc() ***
- slave_destroy() ***
-------------------------------------------------------------
+ HBA PROBE: assume 2 SCSI devices found in scan
+ LLD mid level LLD
+ ===-------------------=========--------------------===------
+ scsi_host_alloc() -->
+ scsi_add_host() ---->
+ scsi_scan_host() -------+
+ |
+ slave_alloc()
+ slave_configure() --> scsi_change_queue_depth()
+ |
+ slave_alloc()
+ slave_configure()
+ |
+ slave_alloc() ***
+ slave_destroy() ***
+
+
+ *** For scsi devices that the mid level tries to scan but do not
+ respond, a slave_alloc(), slave_destroy() pair is called.

If the LLD wants to adjust the default queue settings, it can invoke
scsi_change_queue_depth() in its slave_configure() routine.

-*** For scsi devices that the mid level tries to scan but do not
- respond, a slave_alloc(), slave_destroy() pair is called.
-
When an HBA is being removed it could be as part of an orderly shutdown
associated with the LLD module being unloaded (e.g. with the "rmmod"
command) or in response to a "hot unplug" indicated by sysfs()'s
remove() callback being invoked. In either case, the sequence is the
-same:
+same::
+
+ HBA REMOVE: assume 2 SCSI devices attached
+ LLD mid level LLD
+ ===----------------------=========-----------------===------
+ scsi_remove_host() ---------+
+ |
+ slave_destroy()
+ slave_destroy()
+ scsi_host_put()

- HBA REMOVE: assume 2 SCSI devices attached
-LLD mid level LLD
-===----------------------=========-----------------===------
-scsi_remove_host() ---------+
- |
- slave_destroy()
- slave_destroy()
-scsi_host_put()
-------------------------------------------------------------
-
It may be useful for a LLD to keep track of struct Scsi_Host instances
(a pointer is returned by scsi_host_alloc()). Such instances are "owned"
by the mid-level. struct Scsi_Host instances are freed from
@@ -193,16 +195,15 @@ The hotplug concept may be extended to SCSI devices. Currently, when an
HBA is added, the scsi_scan_host() function causes a scan for SCSI devices
attached to the HBA's SCSI transport. On newer SCSI transports the HBA
may become aware of a new SCSI device _after_ the scan has completed.
-An LLD can use this sequence to make the mid level aware of a SCSI device:
+An LLD can use this sequence to make the mid level aware of a SCSI device::

- SCSI DEVICE hotplug
-LLD mid level LLD
-===-------------------=========--------------------===------
-scsi_add_device() ------+
- |
- slave_alloc()
- slave_configure() [--> scsi_change_queue_depth()]
-------------------------------------------------------------
+ SCSI DEVICE hotplug
+ LLD mid level LLD
+ ===-------------------=========--------------------===------
+ scsi_add_device() ------+
+ |
+ slave_alloc()
+ slave_configure() [--> scsi_change_queue_depth()]

In a similar fashion, an LLD may become aware that a SCSI device has been
removed (unplugged) or the connection to it has been interrupted. Some
@@ -210,15 +211,14 @@ existing SCSI transports (e.g. SPI) may not become aware that a SCSI
device has been removed until a subsequent SCSI command fails which will
probably cause that device to be set offline by the mid level. An LLD that
detects the removal of a SCSI device can instigate its removal from
-upper layers with this sequence:
+upper layers with this sequence::

- SCSI DEVICE hot unplug
-LLD mid level LLD
-===----------------------=========-----------------===------
-scsi_remove_device() -------+
- |
- slave_destroy()
-------------------------------------------------------------
+ SCSI DEVICE hot unplug
+ LLD mid level LLD
+ ===----------------------=========-----------------===------
+ scsi_remove_device() -------+
+ |
+ slave_destroy()

It may be useful for an LLD to keep track of struct scsi_device instances
(a pointer is passed as the parameter to slave_alloc() and
@@ -237,10 +237,16 @@ where they do.

There are 3 reference counting functions of interest associated with
struct Scsi_Host:
- - scsi_host_alloc(): returns a pointer to new instance of struct
+
+ - scsi_host_alloc():
+ returns a pointer to new instance of struct
Scsi_Host which has its reference count ^^ set to 1
- - scsi_host_get(): adds 1 to the reference count of the given instance
- - scsi_host_put(): decrements 1 from the reference count of the given
+
+ - scsi_host_get():
+ adds 1 to the reference count of the given instance
+
+ - scsi_host_put():
+ decrements 1 from the reference count of the given
instance. If the reference count reaches 0 then the given instance
is freed

@@ -254,8 +260,10 @@ to bump its reference count. When it is finished with the pointer it can
use scsi_device_put() to decrement its reference count (and potentially
delete it).

-^^ struct Scsi_Host actually has 2 reference counts which are manipulated
-in parallel by these functions.
+.. Note::
+
+ struct Scsi_Host actually has 2 reference counts which are manipulated
+ in parallel by these functions.

Conventions
@@ -263,17 +271,17 @@ Conventions
First, Linus Torvalds's thoughts on C coding style can be found in the
Documentation/process/coding-style.rst file.

-Next, there is a movement to "outlaw" typedefs introducing synonyms for
+Next, there is a movement to "outlaw" typedefs introducing synonyms for
struct tags. Both can be still found in the SCSI subsystem, but
the typedefs have been moved to a single file, scsi_typedefs.h to
-make their future removal easier, for example:
+make their future removal easier, for example:
"typedef struct scsi_cmnd Scsi_Cmnd;"

Also, most C99 enhancements are encouraged to the extent they are supported
by the relevant gcc compilers. So C99 style structure and array
initializers are encouraged where appropriate. Don't go too far,
VLAs are not properly supported yet. An exception to this is the use of
-"//" style comments; /*...*/ comments are still preferred in Linux.
+``//`` style comments; ``/*...*/`` comments are still preferred in Linux.

Well written, tested and documented code, need not be re-formatted to
comply with the above conventions. For example, the aic7xxx driver
@@ -284,357 +292,358 @@ and Adaptec have their own coding conventions.
Mid level supplied functions
============================
These functions are supplied by the SCSI mid level for use by LLDs.
-The names (i.e. entry points) of these functions are exported
+The names (i.e. entry points) of these functions are exported
so an LLD that is a module can access them. The kernel will
arrange for the SCSI mid level to be loaded and initialized before any LLD
is initialized. The functions below are listed alphabetically and their
-names all start with "scsi_".
+names all start with ``scsi_``.

Summary:
- scsi_add_device - creates new scsi device (lu) instance
- scsi_add_host - perform sysfs registration and set up transport class
- scsi_change_queue_depth - change the queue depth on a SCSI device
- scsi_bios_ptable - return copy of block device's partition table
- scsi_block_requests - prevent further commands being queued to given host
- scsi_host_alloc - return a new scsi_host instance whose refcount==1
- scsi_host_get - increments Scsi_Host instance's refcount
- scsi_host_put - decrements Scsi_Host instance's refcount (free if 0)
- scsi_partsize - parse partition table into cylinders, heads + sectors
- scsi_register - create and register a scsi host adapter instance.
- scsi_remove_device - detach and remove a SCSI device
- scsi_remove_host - detach and remove all SCSI devices owned by host
- scsi_report_bus_reset - report scsi _bus_ reset observed
- scsi_scan_host - scan SCSI bus
- scsi_track_queue_full - track successive QUEUE_FULL events
- scsi_unblock_requests - allow further commands to be queued to given host
- scsi_unregister - [calls scsi_host_put()]
-
-
-Details:
-
-/**
- * scsi_add_device - creates new scsi device (lu) instance
- * @shost: pointer to scsi host instance
- * @channel: channel number (rarely other than 0)
- * @id: target id number
- * @lun: logical unit number
- *
- * Returns pointer to new struct scsi_device instance or
- * ERR_PTR(-ENODEV) (or some other bent pointer) if something is
- * wrong (e.g. no lu responds at given address)
- *
- * Might block: yes
- *
- * Notes: This call is usually performed internally during a scsi
- * bus scan when an HBA is added (i.e. scsi_scan_host()). So it
- * should only be called if the HBA becomes aware of a new scsi
- * device (lu) after scsi_scan_host() has completed. If successful
- * this call can lead to slave_alloc() and slave_configure() callbacks
- * into the LLD.
- *
- * Defined in: drivers/scsi/scsi_scan.c
- **/
-struct scsi_device * scsi_add_device(struct Scsi_Host *shost,
- unsigned int channel,
- unsigned int id, unsigned int lun)
-
-
-/**
- * scsi_add_host - perform sysfs registration and set up transport class
- * @shost: pointer to scsi host instance
- * @dev: pointer to struct device of type scsi class
- *
- * Returns 0 on success, negative errno of failure (e.g. -ENOMEM)
- *
- * Might block: no
- *
- * Notes: Only required in "hotplug initialization model" after a
- * successful call to scsi_host_alloc(). This function does not
- * scan the bus; this can be done by calling scsi_scan_host() or
- * in some other transport-specific way. The LLD must set up
- * the transport template before calling this function and may only
- * access the transport class data after this function has been called.
- *
- * Defined in: drivers/scsi/hosts.c
- **/
-int scsi_add_host(struct Scsi_Host *shost, struct device * dev)
-
-
-/**
- * scsi_change_queue_depth - allow LLD to change queue depth on a SCSI device
- * @sdev: pointer to SCSI device to change queue depth on
- * @tags Number of tags allowed if tagged queuing enabled,
- * or number of commands the LLD can queue up
- * in non-tagged mode (as per cmd_per_lun).
- *
- * Returns nothing
- *
- * Might block: no
- *
- * Notes: Can be invoked any time on a SCSI device controlled by this
- * LLD. [Specifically during and after slave_configure() and prior to
- * slave_destroy().] Can safely be invoked from interrupt code.
- *
- * Defined in: drivers/scsi/scsi.c [see source code for more notes]
- *
- **/
-int scsi_change_queue_depth(struct scsi_device *sdev, int tags)
-
-
-/**
- * scsi_bios_ptable - return copy of block device's partition table
- * @dev: pointer to block device
- *
- * Returns pointer to partition table, or NULL for failure
- *
- * Might block: yes
- *
- * Notes: Caller owns memory returned (free with kfree() )
- *
- * Defined in: drivers/scsi/scsicam.c
- **/
-unsigned char *scsi_bios_ptable(struct block_device *dev)
-
-
-/**
- * scsi_block_requests - prevent further commands being queued to given host
- *
- * @shost: pointer to host to block commands on
- *
- * Returns nothing
- *
- * Might block: no
- *
- * Notes: There is no timer nor any other means by which the requests
- * get unblocked other than the LLD calling scsi_unblock_requests().
- *
- * Defined in: drivers/scsi/scsi_lib.c
-**/
-void scsi_block_requests(struct Scsi_Host * shost)
-
-
-/**
- * scsi_host_alloc - create a scsi host adapter instance and perform basic
- * initialization.
- * @sht: pointer to scsi host template
- * @privsize: extra bytes to allocate in hostdata array (which is the
- * last member of the returned Scsi_Host instance)
- *
- * Returns pointer to new Scsi_Host instance or NULL on failure
- *
- * Might block: yes
- *
- * Notes: When this call returns to the LLD, the SCSI bus scan on
- * this host has _not_ yet been done.
- * The hostdata array (by default zero length) is a per host scratch
- * area for the LLD's exclusive use.
- * Both associated refcounting objects have their refcount set to 1.
- * Full registration (in sysfs) and a bus scan are performed later when
- * scsi_add_host() and scsi_scan_host() are called.
- *
- * Defined in: drivers/scsi/hosts.c .
- **/
-struct Scsi_Host * scsi_host_alloc(struct scsi_host_template * sht,
- int privsize)
-
-
-/**
- * scsi_host_get - increment Scsi_Host instance refcount
- * @shost: pointer to struct Scsi_Host instance
- *
- * Returns nothing
- *
- * Might block: currently may block but may be changed to not block
- *
- * Notes: Actually increments the counts in two sub-objects
- *
- * Defined in: drivers/scsi/hosts.c
- **/
-void scsi_host_get(struct Scsi_Host *shost)
-
-
-/**
- * scsi_host_put - decrement Scsi_Host instance refcount, free if 0
- * @shost: pointer to struct Scsi_Host instance
- *
- * Returns nothing
- *
- * Might block: currently may block but may be changed to not block
- *
- * Notes: Actually decrements the counts in two sub-objects. If the
- * latter refcount reaches 0, the Scsi_Host instance is freed.
- * The LLD need not worry exactly when the Scsi_Host instance is
- * freed, it just shouldn't access the instance after it has balanced
- * out its refcount usage.
- *
- * Defined in: drivers/scsi/hosts.c
- **/
-void scsi_host_put(struct Scsi_Host *shost)
-
-
-/**
- * scsi_partsize - parse partition table into cylinders, heads + sectors
- * @buf: pointer to partition table
- * @capacity: size of (total) disk in 512 byte sectors
- * @cyls: outputs number of cylinders calculated via this pointer
- * @hds: outputs number of heads calculated via this pointer
- * @secs: outputs number of sectors calculated via this pointer
- *
- * Returns 0 on success, -1 on failure
- *
- * Might block: no
- *
- * Notes: Caller owns memory returned (free with kfree() )
- *
- * Defined in: drivers/scsi/scsicam.c
- **/
-int scsi_partsize(unsigned char *buf, unsigned long capacity,
- unsigned int *cyls, unsigned int *hds, unsigned int *secs)
-
-
-/**
- * scsi_register - create and register a scsi host adapter instance.
- * @sht: pointer to scsi host template
- * @privsize: extra bytes to allocate in hostdata array (which is the
- * last member of the returned Scsi_Host instance)
- *
- * Returns pointer to new Scsi_Host instance or NULL on failure
- *
- * Might block: yes
- *
- * Notes: When this call returns to the LLD, the SCSI bus scan on
- * this host has _not_ yet been done.
- * The hostdata array (by default zero length) is a per host scratch
- * area for the LLD.
- *
- * Defined in: drivers/scsi/hosts.c .
- **/
-struct Scsi_Host * scsi_register(struct scsi_host_template * sht,
- int privsize)
-
-
-/**
- * scsi_remove_device - detach and remove a SCSI device
- * @sdev: a pointer to a scsi device instance
- *
- * Returns value: 0 on success, -EINVAL if device not attached
- *
- * Might block: yes
- *
- * Notes: If an LLD becomes aware that a scsi device (lu) has
- * been removed but its host is still present then it can request
- * the removal of that scsi device. If successful this call will
- * lead to the slave_destroy() callback being invoked. sdev is an
- * invalid pointer after this call.
- *
- * Defined in: drivers/scsi/scsi_sysfs.c .
- **/
-int scsi_remove_device(struct scsi_device *sdev)
-
-
-/**
- * scsi_remove_host - detach and remove all SCSI devices owned by host
- * @shost: a pointer to a scsi host instance
- *
- * Returns value: 0 on success, 1 on failure (e.g. LLD busy ??)
- *
- * Might block: yes
- *
- * Notes: Should only be invoked if the "hotplug initialization
- * model" is being used. It should be called _prior_ to
- * scsi_unregister().
- *
- * Defined in: drivers/scsi/hosts.c .
- **/
-int scsi_remove_host(struct Scsi_Host *shost)
-
-
-/**
- * scsi_report_bus_reset - report scsi _bus_ reset observed
- * @shost: a pointer to a scsi host involved
- * @channel: channel (within) host on which scsi bus reset occurred
- *
- * Returns nothing
- *
- * Might block: no
- *
- * Notes: This only needs to be called if the reset is one which
- * originates from an unknown location. Resets originated by the
- * mid level itself don't need to call this, but there should be
- * no harm. The main purpose of this is to make sure that a
- * CHECK_CONDITION is properly treated.
- *
- * Defined in: drivers/scsi/scsi_error.c .
- **/
-void scsi_report_bus_reset(struct Scsi_Host * shost, int channel)
-
-
-/**
- * scsi_scan_host - scan SCSI bus
- * @shost: a pointer to a scsi host instance
- *
- * Might block: yes
- *
- * Notes: Should be called after scsi_add_host()
- *
- * Defined in: drivers/scsi/scsi_scan.c
- **/
-void scsi_scan_host(struct Scsi_Host *shost)
-
-
-/**
- * scsi_track_queue_full - track successive QUEUE_FULL events on given
- * device to determine if and when there is a need
- * to adjust the queue depth on the device.
- * @sdev: pointer to SCSI device instance
- * @depth: Current number of outstanding SCSI commands on this device,
- * not counting the one returned as QUEUE_FULL.
- *
- * Returns 0 - no change needed
- * >0 - adjust queue depth to this new depth
- * -1 - drop back to untagged operation using host->cmd_per_lun
- * as the untagged command depth
- *
- * Might block: no
- *
- * Notes: LLDs may call this at any time and we will do "The Right
- * Thing"; interrupt context safe.
- *
- * Defined in: drivers/scsi/scsi.c .
- **/
-int scsi_track_queue_full(struct scsi_device *sdev, int depth)
-
-
-/**
- * scsi_unblock_requests - allow further commands to be queued to given host
- *
- * @shost: pointer to host to unblock commands on
- *
- * Returns nothing
- *
- * Might block: no
- *
- * Defined in: drivers/scsi/scsi_lib.c .
-**/
-void scsi_unblock_requests(struct Scsi_Host * shost)
-
-
-/**
- * scsi_unregister - unregister and free memory used by host instance
- * @shp: pointer to scsi host instance to unregister.
- *
- * Returns nothing
- *
- * Might block: no
- *
- * Notes: Should not be invoked if the "hotplug initialization
- * model" is being used. Called internally by exit_this_scsi_driver()
- * in the "passive initialization model". Hence a LLD has no need to
- * call this function directly.
- *
- * Defined in: drivers/scsi/hosts.c .
- **/
-void scsi_unregister(struct Scsi_Host * shp)
+
+ - scsi_add_device - creates new scsi device (lu) instance
+ - scsi_add_host - perform sysfs registration and set up transport class
+ - scsi_change_queue_depth - change the queue depth on a SCSI device
+ - scsi_bios_ptable - return copy of block device's partition table
+ - scsi_block_requests - prevent further commands being queued to given host
+ - scsi_host_alloc - return a new scsi_host instance whose refcount==1
+ - scsi_host_get - increments Scsi_Host instance's refcount
+ - scsi_host_put - decrements Scsi_Host instance's refcount (free if 0)
+ - scsi_partsize - parse partition table into cylinders, heads + sectors
+ - scsi_register - create and register a scsi host adapter instance.
+ - scsi_remove_device - detach and remove a SCSI device
+ - scsi_remove_host - detach and remove all SCSI devices owned by host
+ - scsi_report_bus_reset - report scsi _bus_ reset observed
+ - scsi_scan_host - scan SCSI bus
+ - scsi_track_queue_full - track successive QUEUE_FULL events
+ - scsi_unblock_requests - allow further commands to be queued to given host
+ - scsi_unregister - [calls scsi_host_put()]
+
+
+Details::
+
+ /**
+ * scsi_add_device - creates new scsi device (lu) instance
+ * @shost: pointer to scsi host instance
+ * @channel: channel number (rarely other than 0)
+ * @id: target id number
+ * @lun: logical unit number
+ *
+ * Returns pointer to new struct scsi_device instance or
+ * ERR_PTR(-ENODEV) (or some other bent pointer) if something is
+ * wrong (e.g. no lu responds at given address)
+ *
+ * Might block: yes
+ *
+ * Notes: This call is usually performed internally during a scsi
+ * bus scan when an HBA is added (i.e. scsi_scan_host()). So it
+ * should only be called if the HBA becomes aware of a new scsi
+ * device (lu) after scsi_scan_host() has completed. If successful
+ * this call can lead to slave_alloc() and slave_configure() callbacks
+ * into the LLD.
+ *
+ * Defined in: drivers/scsi/scsi_scan.c
+ **/
+ struct scsi_device * scsi_add_device(struct Scsi_Host *shost,
+ unsigned int channel,
+ unsigned int id, unsigned int lun)
+
+
+ /**
+ * scsi_add_host - perform sysfs registration and set up transport class
+ * @shost: pointer to scsi host instance
+ * @dev: pointer to struct device of type scsi class
+ *
+ * Returns 0 on success, negative errno of failure (e.g. -ENOMEM)
+ *
+ * Might block: no
+ *
+ * Notes: Only required in "hotplug initialization model" after a
+ * successful call to scsi_host_alloc(). This function does not
+ * scan the bus; this can be done by calling scsi_scan_host() or
+ * in some other transport-specific way. The LLD must set up
+ * the transport template before calling this function and may only
+ * access the transport class data after this function has been called.
+ *
+ * Defined in: drivers/scsi/hosts.c
+ **/
+ int scsi_add_host(struct Scsi_Host *shost, struct device * dev)
+
+
+ /**
+ * scsi_change_queue_depth - allow LLD to change queue depth on a SCSI device
+ * @sdev: pointer to SCSI device to change queue depth on
+ * @tags Number of tags allowed if tagged queuing enabled,
+ * or number of commands the LLD can queue up
+ * in non-tagged mode (as per cmd_per_lun).
+ *
+ * Returns nothing
+ *
+ * Might block: no
+ *
+ * Notes: Can be invoked any time on a SCSI device controlled by this
+ * LLD. [Specifically during and after slave_configure() and prior to
+ * slave_destroy().] Can safely be invoked from interrupt code.
+ *
+ * Defined in: drivers/scsi/scsi.c [see source code for more notes]
+ *
+ **/
+ int scsi_change_queue_depth(struct scsi_device *sdev, int tags)
+
+
+ /**
+ * scsi_bios_ptable - return copy of block device's partition table
+ * @dev: pointer to block device
+ *
+ * Returns pointer to partition table, or NULL for failure
+ *
+ * Might block: yes
+ *
+ * Notes: Caller owns memory returned (free with kfree() )
+ *
+ * Defined in: drivers/scsi/scsicam.c
+ **/
+ unsigned char *scsi_bios_ptable(struct block_device *dev)
+
+
+ /**
+ * scsi_block_requests - prevent further commands being queued to given host
+ *
+ * @shost: pointer to host to block commands on
+ *
+ * Returns nothing
+ *
+ * Might block: no
+ *
+ * Notes: There is no timer nor any other means by which the requests
+ * get unblocked other than the LLD calling scsi_unblock_requests().
+ *
+ * Defined in: drivers/scsi/scsi_lib.c
+ **/
+ void scsi_block_requests(struct Scsi_Host * shost)
+
+
+ /**
+ * scsi_host_alloc - create a scsi host adapter instance and perform basic
+ * initialization.
+ * @sht: pointer to scsi host template
+ * @privsize: extra bytes to allocate in hostdata array (which is the
+ * last member of the returned Scsi_Host instance)
+ *
+ * Returns pointer to new Scsi_Host instance or NULL on failure
+ *
+ * Might block: yes
+ *
+ * Notes: When this call returns to the LLD, the SCSI bus scan on
+ * this host has _not_ yet been done.
+ * The hostdata array (by default zero length) is a per host scratch
+ * area for the LLD's exclusive use.
+ * Both associated refcounting objects have their refcount set to 1.
+ * Full registration (in sysfs) and a bus scan are performed later when
+ * scsi_add_host() and scsi_scan_host() are called.
+ *
+ * Defined in: drivers/scsi/hosts.c .
+ **/
+ struct Scsi_Host * scsi_host_alloc(struct scsi_host_template * sht,
+ int privsize)
+
+
+ /**
+ * scsi_host_get - increment Scsi_Host instance refcount
+ * @shost: pointer to struct Scsi_Host instance
+ *
+ * Returns nothing
+ *
+ * Might block: currently may block but may be changed to not block
+ *
+ * Notes: Actually increments the counts in two sub-objects
+ *
+ * Defined in: drivers/scsi/hosts.c
+ **/
+ void scsi_host_get(struct Scsi_Host *shost)
+
+
+ /**
+ * scsi_host_put - decrement Scsi_Host instance refcount, free if 0
+ * @shost: pointer to struct Scsi_Host instance
+ *
+ * Returns nothing
+ *
+ * Might block: currently may block but may be changed to not block
+ *
+ * Notes: Actually decrements the counts in two sub-objects. If the
+ * latter refcount reaches 0, the Scsi_Host instance is freed.
+ * The LLD need not worry exactly when the Scsi_Host instance is
+ * freed, it just shouldn't access the instance after it has balanced
+ * out its refcount usage.
+ *
+ * Defined in: drivers/scsi/hosts.c
+ **/
+ void scsi_host_put(struct Scsi_Host *shost)
+
+
+ /**
+ * scsi_partsize - parse partition table into cylinders, heads + sectors
+ * @buf: pointer to partition table
+ * @capacity: size of (total) disk in 512 byte sectors
+ * @cyls: outputs number of cylinders calculated via this pointer
+ * @hds: outputs number of heads calculated via this pointer
+ * @secs: outputs number of sectors calculated via this pointer
+ *
+ * Returns 0 on success, -1 on failure
+ *
+ * Might block: no
+ *
+ * Notes: Caller owns memory returned (free with kfree() )
+ *
+ * Defined in: drivers/scsi/scsicam.c
+ **/
+ int scsi_partsize(unsigned char *buf, unsigned long capacity,
+ unsigned int *cyls, unsigned int *hds, unsigned int *secs)
+
+
+ /**
+ * scsi_register - create and register a scsi host adapter instance.
+ * @sht: pointer to scsi host template
+ * @privsize: extra bytes to allocate in hostdata array (which is the
+ * last member of the returned Scsi_Host instance)
+ *
+ * Returns pointer to new Scsi_Host instance or NULL on failure
+ *
+ * Might block: yes
+ *
+ * Notes: When this call returns to the LLD, the SCSI bus scan on
+ * this host has _not_ yet been done.
+ * The hostdata array (by default zero length) is a per host scratch
+ * area for the LLD.
+ *
+ * Defined in: drivers/scsi/hosts.c .
+ **/
+ struct Scsi_Host * scsi_register(struct scsi_host_template * sht,
+ int privsize)
+
+
+ /**
+ * scsi_remove_device - detach and remove a SCSI device
+ * @sdev: a pointer to a scsi device instance
+ *
+ * Returns value: 0 on success, -EINVAL if device not attached
+ *
+ * Might block: yes
+ *
+ * Notes: If an LLD becomes aware that a scsi device (lu) has
+ * been removed but its host is still present then it can request
+ * the removal of that scsi device. If successful this call will
+ * lead to the slave_destroy() callback being invoked. sdev is an
+ * invalid pointer after this call.
+ *
+ * Defined in: drivers/scsi/scsi_sysfs.c .
+ **/
+ int scsi_remove_device(struct scsi_device *sdev)
+
+
+ /**
+ * scsi_remove_host - detach and remove all SCSI devices owned by host
+ * @shost: a pointer to a scsi host instance
+ *
+ * Returns value: 0 on success, 1 on failure (e.g. LLD busy ??)
+ *
+ * Might block: yes
+ *
+ * Notes: Should only be invoked if the "hotplug initialization
+ * model" is being used. It should be called _prior_ to
+ * scsi_unregister().
+ *
+ * Defined in: drivers/scsi/hosts.c .
+ **/
+ int scsi_remove_host(struct Scsi_Host *shost)
+
+
+ /**
+ * scsi_report_bus_reset - report scsi _bus_ reset observed
+ * @shost: a pointer to a scsi host involved
+ * @channel: channel (within) host on which scsi bus reset occurred
+ *
+ * Returns nothing
+ *
+ * Might block: no
+ *
+ * Notes: This only needs to be called if the reset is one which
+ * originates from an unknown location. Resets originated by the
+ * mid level itself don't need to call this, but there should be
+ * no harm. The main purpose of this is to make sure that a
+ * CHECK_CONDITION is properly treated.
+ *
+ * Defined in: drivers/scsi/scsi_error.c .
+ **/
+ void scsi_report_bus_reset(struct Scsi_Host * shost, int channel)
+
+
+ /**
+ * scsi_scan_host - scan SCSI bus
+ * @shost: a pointer to a scsi host instance
+ *
+ * Might block: yes
+ *
+ * Notes: Should be called after scsi_add_host()
+ *
+ * Defined in: drivers/scsi/scsi_scan.c
+ **/
+ void scsi_scan_host(struct Scsi_Host *shost)
+
+
+ /**
+ * scsi_track_queue_full - track successive QUEUE_FULL events on given
+ * device to determine if and when there is a need
+ * to adjust the queue depth on the device.
+ * @sdev: pointer to SCSI device instance
+ * @depth: Current number of outstanding SCSI commands on this device,
+ * not counting the one returned as QUEUE_FULL.
+ *
+ * Returns 0 - no change needed
+ * >0 - adjust queue depth to this new depth
+ * -1 - drop back to untagged operation using host->cmd_per_lun
+ * as the untagged command depth
+ *
+ * Might block: no
+ *
+ * Notes: LLDs may call this at any time and we will do "The Right
+ * Thing"; interrupt context safe.
+ *
+ * Defined in: drivers/scsi/scsi.c .
+ **/
+ int scsi_track_queue_full(struct scsi_device *sdev, int depth)
+
+
+ /**
+ * scsi_unblock_requests - allow further commands to be queued to given host
+ *
+ * @shost: pointer to host to unblock commands on
+ *
+ * Returns nothing
+ *
+ * Might block: no
+ *
+ * Defined in: drivers/scsi/scsi_lib.c .
+ **/
+ void scsi_unblock_requests(struct Scsi_Host * shost)
+
+
+ /**
+ * scsi_unregister - unregister and free memory used by host instance
+ * @shp: pointer to scsi host instance to unregister.
+ *
+ * Returns nothing
+ *
+ * Might block: no
+ *
+ * Notes: Should not be invoked if the "hotplug initialization
+ * model" is being used. Called internally by exit_this_scsi_driver()
+ * in the "passive initialization model". Hence a LLD has no need to
+ * call this function directly.
+ *
+ * Defined in: drivers/scsi/hosts.c .
+ **/
+ void scsi_unregister(struct Scsi_Host * shp)

@@ -645,9 +654,11 @@ Interface functions are supplied (defined) by LLDs and their function
pointers are placed in an instance of struct scsi_host_template which
is passed to scsi_host_alloc() [or scsi_register() / init_this_scsi_driver()].
Some are mandatory. Interface functions should be declared static. The
-accepted convention is that driver "xyz" will declare its slave_configure()
-function as:
+accepted convention is that driver "xyz" will declare its slave_configure()
+function as::
+
static int xyz_slave_configure(struct scsi_device * sdev);
+
and so forth for all interface functions listed below.

A pointer to this function should be placed in the 'slave_configure' member
@@ -662,388 +673,389 @@ In some cases more detail is given in scsi_host.h than below.
The interface functions are listed below in alphabetical order.

Summary:
- bios_param - fetch head, sector, cylinder info for a disk
- eh_timed_out - notify the host that a command timer expired
- eh_abort_handler - abort given command
- eh_bus_reset_handler - issue SCSI bus reset
- eh_device_reset_handler - issue SCSI device reset
- eh_host_reset_handler - reset host (host bus adapter)
- info - supply information about given host
- ioctl - driver can respond to ioctls
- proc_info - supports /proc/scsi/{driver_name}/{host_no}
- queuecommand - queue scsi command, invoke 'done' on completion
- slave_alloc - prior to any commands being sent to a new device
- slave_configure - driver fine tuning for given device after attach
- slave_destroy - given device is about to be shut down

+ - bios_param - fetch head, sector, cylinder info for a disk
+ - eh_timed_out - notify the host that a command timer expired
+ - eh_abort_handler - abort given command
+ - eh_bus_reset_handler - issue SCSI bus reset
+ - eh_device_reset_handler - issue SCSI device reset
+ - eh_host_reset_handler - reset host (host bus adapter)
+ - info - supply information about given host
+ - ioctl - driver can respond to ioctls
+ - proc_info - supports /proc/scsi/{driver_name}/{host_no}
+ - queuecommand - queue scsi command, invoke 'done' on completion
+ - slave_alloc - prior to any commands being sent to a new device
+ - slave_configure - driver fine tuning for given device after attach
+ - slave_destroy - given device is about to be shut down

-Details:

-/**
- * bios_param - fetch head, sector, cylinder info for a disk
- * @sdev: pointer to scsi device context (defined in
- * include/scsi/scsi_device.h)
- * @bdev: pointer to block device context (defined in fs.h)
- * @capacity: device size (in 512 byte sectors)
- * @params: three element array to place output:
- * params[0] number of heads (max 255)
- * params[1] number of sectors (max 63)
- * params[2] number of cylinders
- *
- * Return value is ignored
- *
- * Locks: none
- *
- * Calling context: process (sd)
- *
- * Notes: an arbitrary geometry (based on READ CAPACITY) is used
- * if this function is not provided. The params array is
- * pre-initialized with made up values just in case this function
- * doesn't output anything.
- *
- * Optionally defined in: LLD
- **/
- int bios_param(struct scsi_device * sdev, struct block_device *bdev,
- sector_t capacity, int params[3])
+Details::

+ /**
+ * bios_param - fetch head, sector, cylinder info for a disk
+ * @sdev: pointer to scsi device context (defined in
+ * include/scsi/scsi_device.h)
+ * @bdev: pointer to block device context (defined in fs.h)
+ * @capacity: device size (in 512 byte sectors)
+ * @params: three element array to place output:
+ * params[0] number of heads (max 255)
+ * params[1] number of sectors (max 63)
+ * params[2] number of cylinders
+ *
+ * Return value is ignored
+ *
+ * Locks: none
+ *
+ * Calling context: process (sd)
+ *
+ * Notes: an arbitrary geometry (based on READ CAPACITY) is used
+ * if this function is not provided. The params array is
+ * pre-initialized with made up values just in case this function
+ * doesn't output anything.
+ *
+ * Optionally defined in: LLD
+ **/
+ int bios_param(struct scsi_device * sdev, struct block_device *bdev,
+ sector_t capacity, int params[3])

-/**
- * eh_timed_out - The timer for the command has just fired
- * @scp: identifies command timing out
- *
- * Returns:
- *
- * EH_HANDLED: I fixed the error, please complete the command
- * EH_RESET_TIMER: I need more time, reset the timer and
- * begin counting again
- * EH_NOT_HANDLED Begin normal error recovery
- *
- *
- * Locks: None held
- *
- * Calling context: interrupt
- *
- * Notes: This is to give the LLD an opportunity to do local recovery.
- * This recovery is limited to determining if the outstanding command
- * will ever complete. You may not abort and restart the command from
- * this callback.
- *
- * Optionally defined in: LLD
- **/
- int eh_timed_out(struct scsi_cmnd * scp)

+ /**
+ * eh_timed_out - The timer for the command has just fired
+ * @scp: identifies command timing out
+ *
+ * Returns:
+ *
+ * EH_HANDLED: I fixed the error, please complete the command
+ * EH_RESET_TIMER: I need more time, reset the timer and
+ * begin counting again
+ * EH_NOT_HANDLED Begin normal error recovery
+ *
+ *
+ * Locks: None held
+ *
+ * Calling context: interrupt
+ *
+ * Notes: This is to give the LLD an opportunity to do local recovery.
+ * This recovery is limited to determining if the outstanding command
+ * will ever complete. You may not abort and restart the command from
+ * this callback.
+ *
+ * Optionally defined in: LLD
+ **/
+ int eh_timed_out(struct scsi_cmnd * scp)

-/**
- * eh_abort_handler - abort command associated with scp
- * @scp: identifies command to be aborted
- *
- * Returns SUCCESS if command aborted else FAILED
- *
- * Locks: None held
- *
- * Calling context: kernel thread
- *
- * Notes: If 'no_async_abort' is defined this callback
- * will be invoked from scsi_eh thread. No other commands
- * will then be queued on current host during eh.
- * Otherwise it will be called whenever scsi_times_out()
- * is called due to a command timeout.
- *
- * Optionally defined in: LLD
- **/
- int eh_abort_handler(struct scsi_cmnd * scp)

+ /**
+ * eh_abort_handler - abort command associated with scp
+ * @scp: identifies command to be aborted
+ *
+ * Returns SUCCESS if command aborted else FAILED
+ *
+ * Locks: None held
+ *
+ * Calling context: kernel thread
+ *
+ * Notes: If 'no_async_abort' is defined this callback
+ * will be invoked from scsi_eh thread. No other commands
+ * will then be queued on current host during eh.
+ * Otherwise it will be called whenever scsi_times_out()
+ * is called due to a command timeout.
+ *
+ * Optionally defined in: LLD
+ **/
+ int eh_abort_handler(struct scsi_cmnd * scp)

-/**
- * eh_bus_reset_handler - issue SCSI bus reset
- * @scp: SCSI bus that contains this device should be reset
- *
- * Returns SUCCESS if command aborted else FAILED
- *
- * Locks: None held
- *
- * Calling context: kernel thread
- *
- * Notes: Invoked from scsi_eh thread. No other commands will be
- * queued on current host during eh.
- *
- * Optionally defined in: LLD
- **/
- int eh_bus_reset_handler(struct scsi_cmnd * scp)

+ /**
+ * eh_bus_reset_handler - issue SCSI bus reset
+ * @scp: SCSI bus that contains this device should be reset
+ *
+ * Returns SUCCESS if command aborted else FAILED
+ *
+ * Locks: None held
+ *
+ * Calling context: kernel thread
+ *
+ * Notes: Invoked from scsi_eh thread. No other commands will be
+ * queued on current host during eh.
+ *
+ * Optionally defined in: LLD
+ **/
+ int eh_bus_reset_handler(struct scsi_cmnd * scp)

-/**
- * eh_device_reset_handler - issue SCSI device reset
- * @scp: identifies SCSI device to be reset
- *
- * Returns SUCCESS if command aborted else FAILED
- *
- * Locks: None held
- *
- * Calling context: kernel thread
- *
- * Notes: Invoked from scsi_eh thread. No other commands will be
- * queued on current host during eh.
- *
- * Optionally defined in: LLD
- **/
- int eh_device_reset_handler(struct scsi_cmnd * scp)

+ /**
+ * eh_device_reset_handler - issue SCSI device reset
+ * @scp: identifies SCSI device to be reset
+ *
+ * Returns SUCCESS if command aborted else FAILED
+ *
+ * Locks: None held
+ *
+ * Calling context: kernel thread
+ *
+ * Notes: Invoked from scsi_eh thread. No other commands will be
+ * queued on current host during eh.
+ *
+ * Optionally defined in: LLD
+ **/
+ int eh_device_reset_handler(struct scsi_cmnd * scp)

-/**
- * eh_host_reset_handler - reset host (host bus adapter)
- * @scp: SCSI host that contains this device should be reset
- *
- * Returns SUCCESS if command aborted else FAILED
- *
- * Locks: None held
- *
- * Calling context: kernel thread
- *
- * Notes: Invoked from scsi_eh thread. No other commands will be
- * queued on current host during eh.
- * With the default eh_strategy in place, if none of the _abort_,
- * _device_reset_, _bus_reset_ or this eh handler function are
- * defined (or they all return FAILED) then the device in question
- * will be set offline whenever eh is invoked.
- *
- * Optionally defined in: LLD
- **/
- int eh_host_reset_handler(struct scsi_cmnd * scp)

+ /**
+ * eh_host_reset_handler - reset host (host bus adapter)
+ * @scp: SCSI host that contains this device should be reset
+ *
+ * Returns SUCCESS if command aborted else FAILED
+ *
+ * Locks: None held
+ *
+ * Calling context: kernel thread
+ *
+ * Notes: Invoked from scsi_eh thread. No other commands will be
+ * queued on current host during eh.
+ * With the default eh_strategy in place, if none of the _abort_,
+ * _device_reset_, _bus_reset_ or this eh handler function are
+ * defined (or they all return FAILED) then the device in question
+ * will be set offline whenever eh is invoked.
+ *
+ * Optionally defined in: LLD
+ **/
+ int eh_host_reset_handler(struct scsi_cmnd * scp)

-/**
- * info - supply information about given host: driver name plus data
- * to distinguish given host
- * @shp: host to supply information about
- *
- * Return ASCII null terminated string. [This driver is assumed to
- * manage the memory pointed to and maintain it, typically for the
- * lifetime of this host.]
- *
- * Locks: none
- *
- * Calling context: process
- *
- * Notes: Often supplies PCI or ISA information such as IO addresses
- * and interrupt numbers. If not supplied struct Scsi_Host::name used
- * instead. It is assumed the returned information fits on one line
- * (i.e. does not included embedded newlines).
- * The SCSI_IOCTL_PROBE_HOST ioctl yields the string returned by this
- * function (or struct Scsi_Host::name if this function is not
- * available).
- * In a similar manner, init_this_scsi_driver() outputs to the console
- * each host's "info" (or name) for the driver it is registering.
- * Also if proc_info() is not supplied, the output of this function
- * is used instead.
- *
- * Optionally defined in: LLD
- **/
- const char * info(struct Scsi_Host * shp)

+ /**
+ * info - supply information about given host: driver name plus data
+ * to distinguish given host
+ * @shp: host to supply information about
+ *
+ * Return ASCII null terminated string. [This driver is assumed to
+ * manage the memory pointed to and maintain it, typically for the
+ * lifetime of this host.]
+ *
+ * Locks: none
+ *
+ * Calling context: process
+ *
+ * Notes: Often supplies PCI or ISA information such as IO addresses
+ * and interrupt numbers. If not supplied struct Scsi_Host::name used
+ * instead. It is assumed the returned information fits on one line
+ * (i.e. does not included embedded newlines).
+ * The SCSI_IOCTL_PROBE_HOST ioctl yields the string returned by this
+ * function (or struct Scsi_Host::name if this function is not
+ * available).
+ * In a similar manner, init_this_scsi_driver() outputs to the console
+ * each host's "info" (or name) for the driver it is registering.
+ * Also if proc_info() is not supplied, the output of this function
+ * is used instead.
+ *
+ * Optionally defined in: LLD
+ **/
+ const char * info(struct Scsi_Host * shp)

-/**
- * ioctl - driver can respond to ioctls
- * @sdp: device that ioctl was issued for
- * @cmd: ioctl number
- * @arg: pointer to read or write data from. Since it points to
- * user space, should use appropriate kernel functions
- * (e.g. copy_from_user() ). In the Unix style this argument
- * can also be viewed as an unsigned long.
- *
- * Returns negative "errno" value when there is a problem. 0 or a
- * positive value indicates success and is returned to the user space.
- *
- * Locks: none
- *
- * Calling context: process
- *
- * Notes: The SCSI subsystem uses a "trickle down" ioctl model.
- * The user issues an ioctl() against an upper level driver
- * (e.g. /dev/sdc) and if the upper level driver doesn't recognize
- * the 'cmd' then it is passed to the SCSI mid level. If the SCSI
- * mid level does not recognize it, then the LLD that controls
- * the device receives the ioctl. According to recent Unix standards
- * unsupported ioctl() 'cmd' numbers should return -ENOTTY.
- *
- * Optionally defined in: LLD
- **/
- int ioctl(struct scsi_device *sdp, int cmd, void *arg)

+ /**
+ * ioctl - driver can respond to ioctls
+ * @sdp: device that ioctl was issued for
+ * @cmd: ioctl number
+ * @arg: pointer to read or write data from. Since it points to
+ * user space, should use appropriate kernel functions
+ * (e.g. copy_from_user() ). In the Unix style this argument
+ * can also be viewed as an unsigned long.
+ *
+ * Returns negative "errno" value when there is a problem. 0 or a
+ * positive value indicates success and is returned to the user space.
+ *
+ * Locks: none
+ *
+ * Calling context: process
+ *
+ * Notes: The SCSI subsystem uses a "trickle down" ioctl model.
+ * The user issues an ioctl() against an upper level driver
+ * (e.g. /dev/sdc) and if the upper level driver doesn't recognize
+ * the 'cmd' then it is passed to the SCSI mid level. If the SCSI
+ * mid level does not recognize it, then the LLD that controls
+ * the device receives the ioctl. According to recent Unix standards
+ * unsupported ioctl() 'cmd' numbers should return -ENOTTY.
+ *
+ * Optionally defined in: LLD
+ **/
+ int ioctl(struct scsi_device *sdp, int cmd, void *arg)

-/**
- * proc_info - supports /proc/scsi/{driver_name}/{host_no}
- * @buffer: anchor point to output to (0==writeto1_read0) or fetch from
- * (1==writeto1_read0).
- * @start: where "interesting" data is written to. Ignored when
- * 1==writeto1_read0.
- * @offset: offset within buffer 0==writeto1_read0 is actually
- * interested in. Ignored when 1==writeto1_read0 .
- * @length: maximum (or actual) extent of buffer
- * @host_no: host number of interest (struct Scsi_Host::host_no)
- * @writeto1_read0: 1 -> data coming from user space towards driver
- * (e.g. "echo some_string > /proc/scsi/xyz/2")
- * 0 -> user what data from this driver
- * (e.g. "cat /proc/scsi/xyz/2")
- *
- * Returns length when 1==writeto1_read0. Otherwise number of chars
- * output to buffer past offset.
- *
- * Locks: none held
- *
- * Calling context: process
- *
- * Notes: Driven from scsi_proc.c which interfaces to proc_fs. proc_fs
- * support can now be configured out of the scsi subsystem.
- *
- * Optionally defined in: LLD
- **/
- int proc_info(char * buffer, char ** start, off_t offset,
- int length, int host_no, int writeto1_read0)

+ /**
+ * proc_info - supports /proc/scsi/{driver_name}/{host_no}
+ * @buffer: anchor point to output to (0==writeto1_read0) or fetch from
+ * (1==writeto1_read0).
+ * @start: where "interesting" data is written to. Ignored when
+ * 1==writeto1_read0.
+ * @offset: offset within buffer 0==writeto1_read0 is actually
+ * interested in. Ignored when 1==writeto1_read0 .
+ * @length: maximum (or actual) extent of buffer
+ * @host_no: host number of interest (struct Scsi_Host::host_no)
+ * @writeto1_read0: 1 -> data coming from user space towards driver
+ * (e.g. "echo some_string > /proc/scsi/xyz/2")
+ * 0 -> user what data from this driver
+ * (e.g. "cat /proc/scsi/xyz/2")
+ *
+ * Returns length when 1==writeto1_read0. Otherwise number of chars
+ * output to buffer past offset.
+ *
+ * Locks: none held
+ *
+ * Calling context: process
+ *
+ * Notes: Driven from scsi_proc.c which interfaces to proc_fs. proc_fs
+ * support can now be configured out of the scsi subsystem.
+ *
+ * Optionally defined in: LLD
+ **/
+ int proc_info(char * buffer, char ** start, off_t offset,
+ int length, int host_no, int writeto1_read0)

-/**
- * queuecommand - queue scsi command, invoke scp->scsi_done on completion
- * @shost: pointer to the scsi host object
- * @scp: pointer to scsi command object
- *
- * Returns 0 on success.
- *
- * If there's a failure, return either:
- *
- * SCSI_MLQUEUE_DEVICE_BUSY if the device queue is full, or
- * SCSI_MLQUEUE_HOST_BUSY if the entire host queue is full
- *
- * On both of these returns, the mid-layer will requeue the I/O
- *
- * - if the return is SCSI_MLQUEUE_DEVICE_BUSY, only that particular
- * device will be paused, and it will be unpaused when a command to
- * the device returns (or after a brief delay if there are no more
- * outstanding commands to it). Commands to other devices continue
- * to be processed normally.
- *
- * - if the return is SCSI_MLQUEUE_HOST_BUSY, all I/O to the host
- * is paused and will be unpaused when any command returns from
- * the host (or after a brief delay if there are no outstanding
- * commands to the host).
- *
- * For compatibility with earlier versions of queuecommand, any
- * other return value is treated the same as
- * SCSI_MLQUEUE_HOST_BUSY.
- *
- * Other types of errors that are detected immediately may be
- * flagged by setting scp->result to an appropriate value,
- * invoking the scp->scsi_done callback, and then returning 0
- * from this function. If the command is not performed
- * immediately (and the LLD is starting (or will start) the given
- * command) then this function should place 0 in scp->result and
- * return 0.
- *
- * Command ownership. If the driver returns zero, it owns the
- * command and must take responsibility for ensuring the
- * scp->scsi_done callback is executed. Note: the driver may
- * call scp->scsi_done before returning zero, but after it has
- * called scp->scsi_done, it may not return any value other than
- * zero. If the driver makes a non-zero return, it must not
- * execute the command's scsi_done callback at any time.
- *
- * Locks: up to and including 2.6.36, struct Scsi_Host::host_lock
- * held on entry (with "irqsave") and is expected to be
- * held on return. From 2.6.37 onwards, queuecommand is
- * called without any locks held.
- *
- * Calling context: in interrupt (soft irq) or process context
- *
- * Notes: This function should be relatively fast. Normally it
- * will not wait for IO to complete. Hence the scp->scsi_done
- * callback is invoked (often directly from an interrupt service
- * routine) some time after this function has returned. In some
- * cases (e.g. pseudo adapter drivers that manufacture the
- * response to a SCSI INQUIRY) the scp->scsi_done callback may be
- * invoked before this function returns. If the scp->scsi_done
- * callback is not invoked within a certain period the SCSI mid
- * level will commence error processing. If a status of CHECK
- * CONDITION is placed in "result" when the scp->scsi_done
- * callback is invoked, then the LLD driver should perform
- * autosense and fill in the struct scsi_cmnd::sense_buffer
- * array. The scsi_cmnd::sense_buffer array is zeroed prior to
- * the mid level queuing a command to an LLD.
- *
- * Defined in: LLD
- **/
- int queuecommand(struct Scsi_Host *shost, struct scsi_cmnd * scp)

+ /**
+ * queuecommand - queue scsi command, invoke scp->scsi_done on completion
+ * @shost: pointer to the scsi host object
+ * @scp: pointer to scsi command object
+ *
+ * Returns 0 on success.
+ *
+ * If there's a failure, return either:
+ *
+ * SCSI_MLQUEUE_DEVICE_BUSY if the device queue is full, or
+ * SCSI_MLQUEUE_HOST_BUSY if the entire host queue is full
+ *
+ * On both of these returns, the mid-layer will requeue the I/O
+ *
+ * - if the return is SCSI_MLQUEUE_DEVICE_BUSY, only that particular
+ * device will be paused, and it will be unpaused when a command to
+ * the device returns (or after a brief delay if there are no more
+ * outstanding commands to it). Commands to other devices continue
+ * to be processed normally.
+ *
+ * - if the return is SCSI_MLQUEUE_HOST_BUSY, all I/O to the host
+ * is paused and will be unpaused when any command returns from
+ * the host (or after a brief delay if there are no outstanding
+ * commands to the host).
+ *
+ * For compatibility with earlier versions of queuecommand, any
+ * other return value is treated the same as
+ * SCSI_MLQUEUE_HOST_BUSY.
+ *
+ * Other types of errors that are detected immediately may be
+ * flagged by setting scp->result to an appropriate value,
+ * invoking the scp->scsi_done callback, and then returning 0
+ * from this function. If the command is not performed
+ * immediately (and the LLD is starting (or will start) the given
+ * command) then this function should place 0 in scp->result and
+ * return 0.
+ *
+ * Command ownership. If the driver returns zero, it owns the
+ * command and must take responsibility for ensuring the
+ * scp->scsi_done callback is executed. Note: the driver may
+ * call scp->scsi_done before returning zero, but after it has
+ * called scp->scsi_done, it may not return any value other than
+ * zero. If the driver makes a non-zero return, it must not
+ * execute the command's scsi_done callback at any time.
+ *
+ * Locks: up to and including 2.6.36, struct Scsi_Host::host_lock
+ * held on entry (with "irqsave") and is expected to be
+ * held on return. From 2.6.37 onwards, queuecommand is
+ * called without any locks held.
+ *
+ * Calling context: in interrupt (soft irq) or process context
+ *
+ * Notes: This function should be relatively fast. Normally it
+ * will not wait for IO to complete. Hence the scp->scsi_done
+ * callback is invoked (often directly from an interrupt service
+ * routine) some time after this function has returned. In some
+ * cases (e.g. pseudo adapter drivers that manufacture the
+ * response to a SCSI INQUIRY) the scp->scsi_done callback may be
+ * invoked before this function returns. If the scp->scsi_done
+ * callback is not invoked within a certain period the SCSI mid
+ * level will commence error processing. If a status of CHECK
+ * CONDITION is placed in "result" when the scp->scsi_done
+ * callback is invoked, then the LLD driver should perform
+ * autosense and fill in the struct scsi_cmnd::sense_buffer
+ * array. The scsi_cmnd::sense_buffer array is zeroed prior to
+ * the mid level queuing a command to an LLD.
+ *
+ * Defined in: LLD
+ **/
+ int queuecommand(struct Scsi_Host *shost, struct scsi_cmnd * scp)

-/**
- * slave_alloc - prior to any commands being sent to a new device
- * (i.e. just prior to scan) this call is made
- * @sdp: pointer to new device (about to be scanned)
- *
- * Returns 0 if ok. Any other return is assumed to be an error and
- * the device is ignored.
- *
- * Locks: none
- *
- * Calling context: process
- *
- * Notes: Allows the driver to allocate any resources for a device
- * prior to its initial scan. The corresponding scsi device may not
- * exist but the mid level is just about to scan for it (i.e. send
- * and INQUIRY command plus ...). If a device is found then
- * slave_configure() will be called while if a device is not found
- * slave_destroy() is called.
- * For more details see the include/scsi/scsi_host.h file.
- *
- * Optionally defined in: LLD
- **/
- int slave_alloc(struct scsi_device *sdp)

+ /**
+ * slave_alloc - prior to any commands being sent to a new device
+ * (i.e. just prior to scan) this call is made
+ * @sdp: pointer to new device (about to be scanned)
+ *
+ * Returns 0 if ok. Any other return is assumed to be an error and
+ * the device is ignored.
+ *
+ * Locks: none
+ *
+ * Calling context: process
+ *
+ * Notes: Allows the driver to allocate any resources for a device
+ * prior to its initial scan. The corresponding scsi device may not
+ * exist but the mid level is just about to scan for it (i.e. send
+ * and INQUIRY command plus ...). If a device is found then
+ * slave_configure() will be called while if a device is not found
+ * slave_destroy() is called.
+ * For more details see the include/scsi/scsi_host.h file.
+ *
+ * Optionally defined in: LLD
+ **/
+ int slave_alloc(struct scsi_device *sdp)

-/**
- * slave_configure - driver fine tuning for given device just after it
- * has been first scanned (i.e. it responded to an
- * INQUIRY)
- * @sdp: device that has just been attached
- *
- * Returns 0 if ok. Any other return is assumed to be an error and
- * the device is taken offline. [offline devices will _not_ have
- * slave_destroy() called on them so clean up resources.]
- *
- * Locks: none
- *
- * Calling context: process
- *
- * Notes: Allows the driver to inspect the response to the initial
- * INQUIRY done by the scanning code and take appropriate action.
- * For more details see the include/scsi/scsi_host.h file.
- *
- * Optionally defined in: LLD
- **/
- int slave_configure(struct scsi_device *sdp)

+ /**
+ * slave_configure - driver fine tuning for given device just after it
+ * has been first scanned (i.e. it responded to an
+ * INQUIRY)
+ * @sdp: device that has just been attached
+ *
+ * Returns 0 if ok. Any other return is assumed to be an error and
+ * the device is taken offline. [offline devices will _not_ have
+ * slave_destroy() called on them so clean up resources.]
+ *
+ * Locks: none
+ *
+ * Calling context: process
+ *
+ * Notes: Allows the driver to inspect the response to the initial
+ * INQUIRY done by the scanning code and take appropriate action.
+ * For more details see the include/scsi/scsi_host.h file.
+ *
+ * Optionally defined in: LLD
+ **/
+ int slave_configure(struct scsi_device *sdp)

-/**
- * slave_destroy - given device is about to be shut down. All
- * activity has ceased on this device.
- * @sdp: device that is about to be shut down
- *
- * Returns nothing
- *
- * Locks: none
- *
- * Calling context: process
- *
- * Notes: Mid level structures for given device are still in place
- * but are about to be torn down. Any per device resources allocated
- * by this driver for given device should be freed now. No further
- * commands will be sent for this sdp instance. [However the device
- * could be re-attached in the future in which case a new instance
- * of struct scsi_device would be supplied by future slave_alloc()
- * and slave_configure() calls.]
- *
- * Optionally defined in: LLD
- **/
- void slave_destroy(struct scsi_device *sdp)
+
+ /**
+ * slave_destroy - given device is about to be shut down. All
+ * activity has ceased on this device.
+ * @sdp: device that is about to be shut down
+ *
+ * Returns nothing
+ *
+ * Locks: none
+ *
+ * Calling context: process
+ *
+ * Notes: Mid level structures for given device are still in place
+ * but are about to be torn down. Any per device resources allocated
+ * by this driver for given device should be freed now. No further
+ * commands will be sent for this sdp instance. [However the device
+ * could be re-attached in the future in which case a new instance
+ * of struct scsi_device would be supplied by future slave_alloc()
+ * and slave_configure() calls.]
+ *
+ * Optionally defined in: LLD
+ **/
+ void slave_destroy(struct scsi_device *sdp)

@@ -1051,24 +1063,31 @@ Data Structures
===============
struct scsi_host_template
-------------------------
-There is one "struct scsi_host_template" instance per LLD ***. It is
+There is one "struct scsi_host_template" instance per LLD [#]_. It is
typically initialized as a file scope static in a driver's header file. That
way members that are not explicitly initialized will be set to 0 or NULL.
Member of interest:
- name - name of driver (may contain spaces, please limit to
+
+ name
+ - name of driver (may contain spaces, please limit to
less than 80 characters)
- proc_name - name used in "/proc/scsi/<proc_name>/<host_no>" and
+
+ proc_name
+ - name used in "/proc/scsi/<proc_name>/<host_no>" and
by sysfs in one of its "drivers" directories. Hence
"proc_name" should only contain characters acceptable
to a Unix file name.
- (*queuecommand)() - primary callback that the mid level uses to inject
+
+ ``(*queuecommand)()``
+ - primary callback that the mid level uses to inject
SCSI commands into an LLD.
+
The structure is defined and commented in include/scsi/scsi_host.h

-*** In extreme situations a single driver may have several instances
- if it controls several different classes of hardware (e.g. an LLD
- that handles both ISA and PCI cards and has a separate instance of
- struct scsi_host_template for each class).
+.. [#] In extreme situations a single driver may have several instances
+ if it controls several different classes of hardware (e.g. an LLD
+ that handles both ISA and PCI cards and has a separate instance of
+ struct scsi_host_template for each class).

struct Scsi_Host
----------------
@@ -1078,42 +1097,58 @@ with "struct scsi_host_template". When a new struct Scsi_Host instance
is created (in scsi_host_alloc() in hosts.c) those common members are
initialized from the driver's struct scsi_host_template instance. Members
of interest:
- host_no - system wide unique number that is used for identifying
+
+ host_no
+ - system wide unique number that is used for identifying
this host. Issued in ascending order from 0.
- can_queue - must be greater than 0; do not send more than can_queue
+ can_queue
+ - must be greater than 0; do not send more than can_queue
commands to the adapter.
- this_id - scsi id of host (scsi initiator) or -1 if not known
- sg_tablesize - maximum scatter gather elements allowed by host.
+ this_id
+ - scsi id of host (scsi initiator) or -1 if not known
+ sg_tablesize
+ - maximum scatter gather elements allowed by host.
Set this to SG_ALL or less to avoid chained SG lists.
Must be at least 1.
- max_sectors - maximum number of sectors (usually 512 bytes) allowed
+ max_sectors
+ - maximum number of sectors (usually 512 bytes) allowed
in a single SCSI command. The default value of 0 leads
to a setting of SCSI_DEFAULT_MAX_SECTORS (defined in
scsi_host.h) which is currently set to 1024. So for a
disk the maximum transfer size is 512 KB when max_sectors
is not defined. Note that this size may not be sufficient
for disk firmware uploads.
- cmd_per_lun - maximum number of commands that can be queued on devices
+ cmd_per_lun
+ - maximum number of commands that can be queued on devices
controlled by the host. Overridden by LLD calls to
scsi_change_queue_depth().
- unchecked_isa_dma - 1=>only use bottom 16 MB of ram (ISA DMA addressing
+ unchecked_isa_dma
+ - 1=>only use bottom 16 MB of ram (ISA DMA addressing
restriction), 0=>can use full 32 bit (or better) DMA
address space
- no_async_abort - 1=>Asynchronous aborts are not supported
- 0=>Timed-out commands will be aborted asynchronously
- hostt - pointer to driver's struct scsi_host_template from which
+ no_async_abort
+ - 1=>Asynchronous aborts are not supported
+ - 0=>Timed-out commands will be aborted asynchronously
+ hostt
+ - pointer to driver's struct scsi_host_template from which
this struct Scsi_Host instance was spawned
- hostt->proc_name - name of LLD. This is the driver name that sysfs uses
- transportt - pointer to driver's struct scsi_transport_template instance
+ hostt->proc_name
+ - name of LLD. This is the driver name that sysfs uses
+ transportt
+ - pointer to driver's struct scsi_transport_template instance
(if any). FC and SPI transports currently supported.
- sh_list - a double linked list of pointers to all struct Scsi_Host
+ sh_list
+ - a double linked list of pointers to all struct Scsi_Host
instances (currently ordered by ascending host_no)
- my_devices - a double linked list of pointers to struct scsi_device
+ my_devices
+ - a double linked list of pointers to struct scsi_device
instances that belong to this host.
- hostdata[0] - area reserved for LLD at end of struct Scsi_Host. Size
+ hostdata[0]
+ - area reserved for LLD at end of struct Scsi_Host. Size
is set by the second argument (named 'xtr_bytes') to
scsi_host_alloc() or scsi_register().
- vendor_id - a unique value that identifies the vendor supplying
+ vendor_id
+ - a unique value that identifies the vendor supplying
the LLD for the Scsi_Host. Used most often in validating
vendor-specific message requests. Value consists of an
identifier type and a vendor-specific value.
@@ -1136,26 +1171,35 @@ commands become queued against the LLD than are indicated by
scsi_change_queue_depth() (or struct Scsi_Host::cmd_per_lun). There will
be at least one instance of struct scsi_cmnd available for each SCSI device.
Members of interest:
- cmnd - array containing SCSI command
- cmnd_len - length (in bytes) of SCSI command
- sc_data_direction - direction of data transfer in data phase. See
- "enum dma_data_direction" in include/linux/dma-mapping.h
- request_bufflen - number of data bytes to transfer (0 if no data phase)
- use_sg - ==0 -> no scatter gather list, hence transfer data
+
+ cmnd
+ - array containing SCSI command
+ cmnd_len
+ - length (in bytes) of SCSI command
+ sc_data_direction
+ - direction of data transfer in data phase. See
+ "enum dma_data_direction" in include/linux/dma-mapping.h
+ request_bufflen
+ - number of data bytes to transfer (0 if no data phase)
+ use_sg
+ - ==0 -> no scatter gather list, hence transfer data
to/from request_buffer
- >0 -> scatter gather list (actually an array) in
request_buffer with use_sg elements
- request_buffer - either contains data buffer or scatter gather list
+ request_buffer
+ - either contains data buffer or scatter gather list
depending on the setting of use_sg. Scatter gather
elements are defined by 'struct scatterlist' found
in include/linux/scatterlist.h .
- done - function pointer that should be invoked by LLD when the
+ done
+ - function pointer that should be invoked by LLD when the
SCSI command is completed (successfully or otherwise).
Should only be called by an LLD if the LLD has accepted
the command (i.e. queuecommand() returned or will return
0). The LLD may invoke 'done' prior to queuecommand()
finishing.
- result - should be set by LLD prior to calling 'done'. A value
+ result
+ - should be set by LLD prior to calling 'done'. A value
of 0 implies a successfully completed command (and all
data (if any) has been transferred to or from the SCSI
target device). 'result' is a 32 bit unsigned integer that
@@ -1163,7 +1207,8 @@ Members of interest:
in the LSB. See include/scsi/scsi.h status_byte(),
msg_byte(), host_byte() and driver_byte() macros and
related constants.
- sense_buffer - an array (maximum size: SCSI_SENSE_BUFFERSIZE bytes) that
+ sense_buffer
+ - an array (maximum size: SCSI_SENSE_BUFFERSIZE bytes) that
should be written when the SCSI status (LSB of 'result')
is set to CHECK_CONDITION (2). When CHECK_CONDITION is
set, if the top nibble of sense_buffer[0] has the value 7
@@ -1173,9 +1218,11 @@ Members of interest:
retrieve the sense buffer. The latter strategy is error
prone in the presence of command queuing so the LLD should
always "auto-sense".
- device - pointer to scsi_device object that this command is
+ device
+ - pointer to scsi_device object that this command is
associated with.
- resid - an LLD should set this signed integer to the requested
+ resid
+ - an LLD should set this signed integer to the requested
transfer length (i.e. 'request_bufflen') less the number
of bytes that are actually transferred. 'resid' is
preset to 0 so an LLD can ignore it if it cannot detect
@@ -1183,7 +1230,8 @@ Members of interest:
should set 'resid' prior to invoking 'done'. The most
interesting case is data transfers from a SCSI target
device (e.g. READs) that underrun.
- underflow - LLD should place (DID_ERROR << 16) in 'result' if
+ underflow
+ - LLD should place (DID_ERROR << 16) in 'result' if
actual number of bytes transferred is less than this
figure. Not many LLDs implement this check and some that
do just output an error message to the log rather than
@@ -1196,10 +1244,13 @@ when such data transfers have sense keys of MEDIUM ERROR and HARDWARE ERROR
(and possibly RECOVERED ERROR). In these cases if a LLD is in doubt how much
data has been received then the safest approach is to indicate no bytes have
been received. For example: to indicate that no valid data has been received
-a LLD might use these helpers:
+a LLD might use these helpers::
+
scsi_set_resid(SCpnt, scsi_bufflen(SCpnt));
+
where 'SCpnt' is a pointer to a scsi_cmnd object. To indicate only three 512
-bytes blocks has been received 'resid' could be set like this:
+bytes blocks has been received 'resid' could be set like this::
+
scsi_set_resid(SCpnt, scsi_bufflen(SCpnt) - (3 * 512));

The scsi_cmnd structure is defined in include/scsi/scsi_cmnd.h
@@ -1207,8 +1258,8 @@ The scsi_cmnd structure is defined in include/scsi/scsi_cmnd.h

Locks
=====
-Each struct Scsi_Host instance has a spin_lock called struct
-Scsi_Host::default_lock which is initialized in scsi_host_alloc() [found in
+Each struct Scsi_Host instance has a spin_lock called struct
+Scsi_Host::default_lock which is initialized in scsi_host_alloc() [found in
hosts.c]. Within the same function the struct Scsi_Host::host_lock pointer
is initialized to point at default_lock. Thereafter lock and unlock
operations performed by the mid level use the struct Scsi_Host::host_lock
@@ -1222,13 +1273,14 @@ Autosense (or auto-sense) is defined in the SAM-2 document as "the
automatic return of sense data to the application client coincident
with the completion of a SCSI command" when a status of CHECK CONDITION
occurs. LLDs should perform autosense. This should be done when the LLD
-detects a CHECK CONDITION status by either:
+detects a CHECK CONDITION status by either:
+
a) instructing the SCSI protocol (e.g. SCSI Parallel Interface (SPI))
to perform an extra data in phase on such responses
b) or, the LLD issuing a REQUEST SENSE command itself

Either way, when a status of CHECK CONDITION is detected, the mid level
-decides whether the LLD has performed autosense by checking struct
+decides whether the LLD has performed autosense by checking struct
scsi_cmnd::sense_buffer[0] . If this byte has an upper nibble of 7 (or 0xf)
then autosense is assumed to have taken place. If it has another value (and
this byte is initialized to 0 before each command) then the mid level will
@@ -1242,7 +1294,7 @@ to perform autosense.

Changes since lk 2.4 series
===========================
-io_request_lock has been replaced by several finer grained locks. The lock
+io_request_lock has been replaced by several finer grained locks. The lock
relevant to LLDs is struct Scsi_Host::host_lock and there is
one per SCSI host.

@@ -1250,9 +1302,9 @@ The older error handling mechanism has been removed. This means the
LLD interface functions abort() and reset() have been removed.
The struct scsi_host_template::use_new_eh_code flag has been removed.

-In the 2.4 series the SCSI subsystem configuration descriptions were
-aggregated with the configuration descriptions from all other Linux
-subsystems in the Documentation/Configure.help file. In the 2.6 series,
+In the 2.4 series the SCSI subsystem configuration descriptions were
+aggregated with the configuration descriptions from all other Linux
+subsystems in the Documentation/Configure.help file. In the 2.6 series,
the SCSI subsystem now has its own (much smaller) drivers/scsi/Kconfig
file that contains both configuration and help information.

@@ -1265,16 +1317,18 @@ to support it.
Credits
=======
The following people have contributed to this document:
- Mike Anderson <andmike at us dot ibm dot com>
- James Bottomley <James dot Bottomley at hansenpartnership dot com>
- Patrick Mansfield <patmans at us dot ibm dot com>
- Christoph Hellwig <hch at infradead dot org>
- Doug Ledford <dledford at redhat dot com>
- Andries Brouwer <Andries dot Brouwer at cwi dot nl>
- Randy Dunlap <rdunlap at xenotime dot net>
- Alan Stern <stern at rowland dot harvard dot edu>
+
+ - Mike Anderson <andmike at us dot ibm dot com>
+ - James Bottomley <James dot Bottomley at hansenpartnership dot com>
+ - Patrick Mansfield <patmans at us dot ibm dot com>
+ - Christoph Hellwig <hch at infradead dot org>
+ - Doug Ledford <dledford at redhat dot com>
+ - Andries Brouwer <Andries dot Brouwer at cwi dot nl>
+ - Randy Dunlap <rdunlap at xenotime dot net>
+ - Alan Stern <stern at rowland dot harvard dot edu>

Douglas Gilbert
dgilbert at interlog dot com
+
21st September 2004
diff --git a/scripts/documentation-file-ref-check b/scripts/documentation-file-ref-check
index 997202a18ddb..9a8cc10cffd0 100755
--- a/scripts/documentation-file-ref-check
+++ b/scripts/documentation-file-ref-check
@@ -12,7 +12,7 @@ use Getopt::Long qw(:config no_auto_abbrev);
# to mention a past documentation file, for example, to give credits for
# the original work.
my %false_positives = (
- "Documentation/scsi/scsi_mid_low_api.txt" => "Documentation/Configure.help",
+ "Documentation/scsi/scsi_mid_low_api.rst" => "Documentation/Configure.help",
"drivers/vhost/vhost.c" => "Documentation/virtual/lguest/lguest.c",
);

--
2.21.1