Ok, I'm reading the code and trying to update the kerneldoc comments (first
stab at it attached, a Documentation/DocBook/scsi_midlayer.tmpl is in the
works), and I have a few random questions from the read-through:
Why does __scsi_put_command() pass in both a Scsi_Host * and struct device *
when scsi_get_command() uses dev->host? Is dev->host not guaranteed to be
set?
scsi_put_command() notes "the command must not belong to any lists" but then
inside the function it says "serious error if the command hasn't come form a
device list" and does a BUG_ON(list_empty(&cmd->list));
scsi_setup_command_freelist() is protection against OOM locking the system
solid, right? Makes sure there's always preallocated memory to send at least
one SCSI command at a time to each host so we can swap enough to free more?
scsi_dispatch_command() I _think_ a nonzero return means the command was
rejected and the device queue needs to be plugged, but I'm not 100% certain
what that means.
The rest sort of seems to make sense, although the kerneldoc comments in
include/scsi/scsi_device.h are before #defines instead of before function
definitions so the make xmldocs infrastructure (something in either
scripts/basic/docproc.c or scripts/kernel-doc) skips right over it
because it can't figure out the argument types. Separate issue, todo item for
later...
Rob
--
"One of my most productive days was throwing away 1000 lines of code."
- Ken Thompson.
diff -r a868e8217782 drivers/scsi/scsi.c
--- a/drivers/scsi/scsi.c Mon Oct 22 19:40:02 2007 -0700
+++ b/drivers/scsi/scsi.c Thu Oct 25 06:01:43 2007 -0500
@@ -122,6 +122,11 @@ static const char *const scsi_device_typ
"Automation/Drive ",
};
+/**
+ * scsi_device_type - Return 17 char string indicating device type.
+ * @type: type number to look up
+ */
+
const char * scsi_device_type(unsigned type)
{
if (type == 0x1e)
@@ -156,6 +161,14 @@ static struct scsi_host_cmd_pool scsi_cm
static DEFINE_MUTEX(host_cmd_pool_mutex);
+/**
+ * __scsi_get_command - Allocate a struct scsi_cmnd
+ * @shost: host to transmit command
+ * @gfp_mask: allocation mask
+ *
+ * Description: allocate a struct scsi_cmd from host's slab, recycling from the
+ * host's free_list if necessary.
+ */
struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
{
struct scsi_cmnd *cmd;
@@ -179,13 +192,10 @@ struct scsi_cmnd *__scsi_get_command(str
}
EXPORT_SYMBOL_GPL(__scsi_get_command);
-/*
- * Function: scsi_get_command()
- *
- * Purpose: Allocate and setup a scsi command block
- *
- * Arguments: dev - parent scsi device
- * gfp_mask- allocator flags
+/**
+ * scsi_get_command - Allocate and setup a scsi command block
+ * @dev: parent scsi device
+ * @gfp_mask: allocator flags
*
* Returns: The allocated scsi command structure.
*/
@@ -217,6 +227,12 @@ struct scsi_cmnd *scsi_get_command(struc
}
EXPORT_SYMBOL(scsi_get_command);
+/**
+ * __scsi_put_command - Free a struct scsi_cmnd
+ * @shost: dev->host
+ * @cmd: Command to free
+ * @dev: parent scsi device
+ */
void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
struct device *dev)
{
@@ -237,12 +253,9 @@ void __scsi_put_command(struct Scsi_Host
}
EXPORT_SYMBOL(__scsi_put_command);
-/*
- * Function: scsi_put_command()
- *
- * Purpose: Free a scsi command block
- *
- * Arguments: cmd - command block to free
+/**
+ * scsi_put_command - Free a scsi command block
+ * @cmd: command block to free
*
* Returns: Nothing.
*
@@ -263,12 +276,13 @@ void scsi_put_command(struct scsi_cmnd *
}
EXPORT_SYMBOL(scsi_put_command);
-/*
- * Function: scsi_setup_command_freelist()
- *
- * Purpose: Setup the command freelist for a scsi host.
- *
- * Arguments: shost - host to allocate the freelist for.
+/**
+ * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
+ * @shost: host to allocate the freelist for.
+ *
+ * Description: The command freelist protects against system-wide out of memory
+ * deadlock by preallocating one SCSI command structure for each host, so the
+ * system can always write to a swap file on a device associated with that host.
*
* Returns: Nothing.
*/
@@ -318,12 +332,9 @@ int scsi_setup_command_freelist(struct S
}
-/*
- * Function: scsi_destroy_command_freelist()
- *
- * Purpose: Release the command freelist for a scsi host.
- *
- * Arguments: shost - host that's freelist is going to be destroyed
+/**
+ * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
+ * @shost: host that's freelist is going to be destroyed
*/
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
{
@@ -441,8 +452,12 @@ void scsi_log_completion(struct scsi_cmn
}
#endif
-/*
- * Assign a serial number to the request for error recovery
+/**
+ * scsi_cmd_get_serial - Assign a serial number to a command
+ * @host: the scsi host
+ * @cmd: command to assign serial number to
+ *
+ * Description: a serial number identifies a request for error recovery
* and debugging purposes. Protected by the Host_Lock of host.
*/
static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
@@ -452,14 +467,12 @@ static inline void scsi_cmd_get_serial(s
cmd->serial_number = host->cmd_serial_number++;
}
-/*
- * Function: scsi_dispatch_command
- *
- * Purpose: Dispatch a command to the low-level driver.
- *
- * Arguments: cmd - command block we are dispatching.
- *
- * Notes:
+/**
+ * scsi_dispatch_command - Dispatch a command to the low-level driver.
+ * @cmd: command block we are dispatching.
+ *
+ * Return: nonzero return request was rejected and device's queue needs to be
+ * plugged.
*/
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
@@ -585,7 +598,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *
/**
* scsi_req_abort_cmd -- Request command recovery for the specified command
- * cmd: pointer to the SCSI command of interest
+ * @cmd: pointer to the SCSI command of interest
*
* This function requests that SCSI Core start recovery for the
* command by deleting the timer and adding the command to the eh
@@ -606,9 +619,9 @@ EXPORT_SYMBOL(scsi_req_abort_cmd);
* @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
* ownership back to SCSI Core -- i.e. the LLDD has finished with it.
*
- * This function is the mid-level's (SCSI Core) interrupt routine, which
- * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
- * the command to the done queue for further processing.
+ * Description: This function is the mid-level's (SCSI Core) interrupt routine,
+ * which regains ownership of the SCSI command (de facto) from a LLDD, and
+ * enqueues the command to the done queue for further processing.
*
* This is the producer of the done queue who enqueues at the tail.
*
@@ -660,10 +673,11 @@ static struct scsi_driver *scsi_cmd_to_d
return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
}
-/*
- * Function: scsi_finish_command
- *
- * Purpose: Pass command off to upper layer for finishing of I/O
+/**
+ * scsi_finish_command
+ * @cmd: the command
+ *
+ * Description: Pass command off to upper layer for finishing of I/O
* request, waking processes that are waiting on results,
* etc.
*/
@@ -708,18 +722,14 @@ void scsi_finish_command(struct scsi_cmn
}
EXPORT_SYMBOL(scsi_finish_command);
-/*
- * Function: scsi_adjust_queue_depth()
- *
- * Purpose: Allow low level drivers to tell us to change the queue depth
- * on a specific SCSI device
- *
- * Arguments: sdev - SCSI Device in question
- * tagged - Do we use tagged queueing (non-0) or do we treat
- * this device as an untagged device (0)
- * tags - Number of tags allowed if tagged queueing enabled,
- * or number of commands the low level driver can
- * queue up in non-tagged mode (as per cmd_per_lun).
+/**
+ * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
+ * @sdev: SCSI Device in question
+ * @tagged: Do we use tagged queueing (non-0) or do we treat
+ * this device as an untagged device (0)
+ * @tags: Number of tags allowed if tagged queueing enabled,
+ * or number of commands the low level driver can
+ * queue up in non-tagged mode (as per cmd_per_lun).
*
* Returns: Nothing
*
@@ -772,20 +782,17 @@ void scsi_adjust_queue_depth(struct scsi
}
EXPORT_SYMBOL(scsi_adjust_queue_depth);
-/*
- * Function: scsi_track_queue_full()
- *
- * Purpose: This function will track successive QUEUE_FULL events on a
+/**
+ * scsi_track_queue_full
+ * @sdev: SCSI Device in question
+ * @depth: Current number of outstanding SCSI commands on this device,
+ * not counting the one returned as QUEUE_FULL.
+ *
+ * Description: This function will track successive QUEUE_FULL events on a
* specific SCSI device to determine if and when there is a
* need to adjust the queue depth on the device.
*
- * Arguments: sdev - SCSI Device in question
- * 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
+ * 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
*
@@ -824,10 +831,10 @@ EXPORT_SYMBOL(scsi_track_queue_full);
EXPORT_SYMBOL(scsi_track_queue_full);
/**
- * scsi_device_get - get an addition reference to a scsi_device
+ * scsi_device_get - get an additional reference to a scsi_device
* @sdev: device to get a reference to
*
- * Gets a reference to the scsi_device and increments the use count
+ * Description: Gets a reference to the scsi_device and increments the use count
* of the underlying LLDD module. You must hold host_lock of the
* parent Scsi_Host or already have a reference when calling this.
*/
@@ -849,8 +856,8 @@ EXPORT_SYMBOL(scsi_device_get);
* scsi_device_put - release a reference to a scsi_device
* @sdev: device to release a reference on.
*
- * Release a reference to the scsi_device and decrements the use count
- * of the underlying LLDD module. The device is freed once the last
+ * Description: Release a reference to the scsi_device and decrements the use
+ * count of the underlying LLDD module. The device is freed once the last
* user vanishes.
*/
void scsi_device_put(struct scsi_device *sdev)
@@ -867,7 +874,7 @@ void scsi_device_put(struct scsi_device
}
EXPORT_SYMBOL(scsi_device_put);
-/* helper for shost_for_each_device, thus not documented */
+/* helper for shost_for_each_device, see that for documentation */
struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
struct scsi_device *prev)
{
@@ -895,8 +902,10 @@ EXPORT_SYMBOL(__scsi_iterate_devices);
/**
* starget_for_each_device - helper to walk all devices of a target
* @starget: target whose devices we want to iterate over.
- *
- * This traverses over each devices of @shost. The devices have
+ * @data: Opaque passed to each function call.
+ * @fn: Function to call on each device
+ *
+ * Description: This traverses over each device of @shost. The devices have
* a reference that must be released by scsi_host_put when breaking
* out of the loop.
*/
@@ -919,8 +928,8 @@ EXPORT_SYMBOL(starget_for_each_device);
* @starget: SCSI target pointer
* @lun: SCSI Logical Unit Number
*
- * Looks up the scsi_device with the specified @lun for a give
- * @starget. The returned scsi_device does not have an additional
+ * Description: Looks up the scsi_device with the specified @lun for a given
+ * @starget. The returned scsi_device does not have an additional
* reference. You must hold the host's host_lock over this call and
* any access to the returned scsi_device.
*
@@ -947,9 +956,9 @@ EXPORT_SYMBOL(__scsi_device_lookup_by_ta
* @starget: SCSI target pointer
* @lun: SCSI Logical Unit Number
*
- * Looks up the scsi_device with the specified @channel, @id, @lun for a
- * give host. The returned scsi_device has an additional reference that
- * needs to be release with scsi_host_put once you're done with it.
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a given host. The returned scsi_device has an additional reference that
+ * needs to be released with scsi_host_put once you're done with it.
**/
struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
uint lun)
@@ -972,13 +981,13 @@ EXPORT_SYMBOL(scsi_device_lookup_by_targ
* scsi_device_lookup - find a device given the host (UNLOCKED)
* @shost: SCSI host pointer
* @channel: SCSI channel (zero if only one channel)
- * @pun: SCSI target number (physical unit number)
+ * @id: SCSI target number (physical unit number)
* @lun: SCSI Logical Unit Number
*
- * Looks up the scsi_device with the specified @channel, @id, @lun for a
- * give host. The returned scsi_device does not have an additional reference.
- * You must hold the host's host_lock over this call and any access to the
- * returned scsi_device.
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a give host. The returned scsi_device does not have an additional
+ * reference. You must hold the host's host_lock over this call and any access
+ * to the returned scsi_device.
*
* Note: The only reason why drivers would want to use this is because
* they're need to access the device list in irq context. Otherwise you
@@ -1006,9 +1015,9 @@ EXPORT_SYMBOL(__scsi_device_lookup);
* @id: SCSI target number (physical unit number)
* @lun: SCSI Logical Unit Number
*
- * Looks up the scsi_device with the specified @channel, @id, @lun for a
- * give host. The returned scsi_device has an additional reference that
- * needs to be release with scsi_host_put once you're done with it.
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a give host. The returned scsi_device has an additional reference that
+ * needs to be released with scsi_host_put once you're done with it.
**/
struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
uint channel, uint id, uint lun)
