Since scsi_target_unblock() uses starget_for_each_device(), since starget_for_each_device() uses scsi_device_get(), since scsi_device_get() fails after unloading of the LLD kernel module has been started scsi_target_unblock() may skip devices that were affected by scsi_target_block(). Ensure that __scsi_remove_device() does not hang for blocked SCSI devices. This patch avoids that unloading the ib_srp kernel module can trigger the following hang: Call Trace: schedule+0x35/0x80 schedule_timeout+0x237/0x2d0 io_schedule_timeout+0xa6/0x110 wait_for_completion_io+0xa3/0x110 blk_execute_rq+0xdf/0x120 scsi_execute+0xce/0x150 [scsi_mod] scsi_execute_req_flags+0x8f/0xf0 [scsi_mod] sd_sync_cache+0xa9/0x190 [sd_mod] sd_shutdown+0x6a/0x100 [sd_mod] sd_remove+0x64/0xc0 [sd_mod] __device_release_driver+0x8d/0x120 device_release_driver+0x1e/0x30 bus_remove_device+0xf9/0x170 device_del+0x127/0x240 __scsi_remove_device+0xc1/0xd0 [scsi_mod] scsi_forget_host+0x57/0x60 [scsi_mod] scsi_remove_host+0x72/0x110 [scsi_mod] srp_remove_work+0x8b/0x200 [ib_srp] Reported-by: Israel Rukshin <israelr@xxxxxxxxxxxx> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> Cc: Max Gurtovoy <maxg@xxxxxxxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxx> Cc: Song Liu <songliubraving@xxxxxx> --- drivers/scsi/scsi_sysfs.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 82dfe07b1d47..e090c35ba6ee 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -1299,6 +1299,15 @@ void __scsi_remove_device(struct scsi_device *sdev) * device. */ scsi_device_set_state(sdev, SDEV_DEL); + /* + * Since scsi_target_unblock() is a no-op after unloading of the SCSI + * LLD has started, explicitly restart the queue. Do this after the + * device state has been changed into SDEV_DEL because + * scsi_prep_state_check() returns BLKPREP_KILL for the SDEV_DEL state + * Do this before calling blk_cleanup_queue() to avoid that that + * function encounters a stopped queue. + */ + scsi_start_queue(sdev); blk_cleanup_queue(sdev->request_queue); cancel_work_sync(&sdev->requeue_work); -- 2.12.2
