diff mbox series

scsi: device_handler: alua: Remove a might_sleep() annotation

Message ID 20230118180557.1212577-1-bvanassche@acm.org
State New
Headers show
Series scsi: device_handler: alua: Remove a might_sleep() annotation | expand

Commit Message

Bart Van Assche Jan. 18, 2023, 6:05 p.m. UTC 
The might_sleep() annotation in alua_rtpg_queue() is not correct since the
command completion code may call this function from atomic context.
Calling alua_rtpg_queue() from atomic context in the command completion
path is fine since request submitters must hold an sdev reference until
command execution has completed. This patch fixes the following kernel
complaint:

BUG: sleeping function called from invalid context at drivers/scsi/device_handler/scsi_dh_alua.c:992
Call Trace:
 dump_stack_lvl+0xac/0x100
 __might_resched+0x284/0x2c8
 alua_rtpg_queue+0x3c/0x98 [scsi_dh_alua]
 alua_check+0x122/0x250 [scsi_dh_alua]
 alua_check_sense+0x172/0x228 [scsi_dh_alua]
 scsi_check_sense+0x8a/0x2e0
 scsi_decide_disposition+0x286/0x298
 scsi_complete+0x6a/0x108
 blk_complete_reqs+0x6e/0x88
 __do_softirq+0x13e/0x6b8
 __irq_exit_rcu+0x14a/0x170
 irq_exit_rcu+0x22/0x50
 do_ext_irq+0x10a/0x1d0

Reported-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Tested-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Martin K. Petersen Jan. 19, 2023, 12:47 a.m. UTC | #1 
Bart,

> The might_sleep() annotation in alua_rtpg_queue() is not correct since
> the command completion code may call this function from atomic
> context.  Calling alua_rtpg_queue() from atomic context in the command
> completion path is fine since request submitters must hold an sdev
> reference until command execution has completed. This patch fixes the
> following kernel complaint:

Applied to 6.2/scsi-fixes, thanks!
diff mbox series

Patch

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 55a5073248f8..362fa631f39b 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -987,6 +987,9 @@  static void alua_rtpg_work(struct work_struct *work)
  *
  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
  * That function is responsible for calling @qdata->fn().
+ *
+ * Context: may be called from atomic context (alua_check()) only if the caller
+ *	holds an sdev reference.
  */
 static bool alua_rtpg_queue(struct alua_port_group *pg,
 			    struct scsi_device *sdev,
@@ -995,8 +998,6 @@  static bool alua_rtpg_queue(struct alua_port_group *pg,
 	int start_queue = 0;
 	unsigned long flags;
 
-	might_sleep();
-
 	if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 		return false;