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

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

Link: https://lore.kernel.org/r/20230118180557.1212577-1-bvanassche@acm.org
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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 49cc18a..29a2865 100644 (file)
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -981,6 +981,9 @@ queue_rtpg:
  *
  * 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,
@@ -989,8 +992,6 @@ 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;