On 4/17/2017 8:34 PM, Bart Van Assche wrote:
__scsi_remove_device() hangs if it is waiting for the SYNCHRONIZE CACHE
command submitted by the sd driver to finish if the block layer queue is
stopped and does not get restarted. This patch series avoids that that
hang occurs.
Changes compared to v2:
- Moved the "stop_disk" assignment after the sdkp check in the sd driver.
- Added a completion function for asynchronous SYNCHRONIZE CACHE commands.
- Added "disk" and "done" arguments to scsi_execute_async().
Changes compared to v1:
- Reworked the approach of this patch series.
Bart Van Assche (4):
Introduce scsi_start_queue()
Introduce scsi_execute_async()
sd: Make synchronize cache upon shutdown asynchronous
Avoid that __scsi_remove_device() hangs
drivers/scsi/scsi_lib.c | 114 ++++++++++++++++++++++++++++++++++-----------
drivers/scsi/scsi_priv.h | 1 +
drivers/scsi/scsi_sysfs.c | 9 ++++
drivers/scsi/sd.c | 45 ++++++++++++++++--
include/scsi/scsi_device.h | 5 ++
5 files changed, 142 insertions(+), 32 deletions(-)
Hi Bart,
I tested those patches and I got a NULL dereference at sd_sync_cache_done().
The test is unloading ib_srp while one port is down.
The previous version worked fine.
From the log:
[ 190.260240] sd 8:0:0:0: [sdc] Synchronizing SCSI cache
[ 190.266412] scsi 8:0:0:0: rejecting I/O to dead device
[ 190.272412] BUG: unable to handle kernel NULL pointer dereference at
00000000000002f0
[ 190.281102] IP: sd_sync_cache_done+0x1b/0x80 [sd_mod]
[ 190.482738] Call Trace:
[ 190.486052] blk_finish_request+0x73/0x130
[ 190.491007] __blk_end_bidi_request+0x2d/0x40
[ 190.496215] __blk_end_request_all+0x1f/0x40
[ 190.501338] blk_peek_request+0x1c5/0x2b0
[ 190.506203] scsi_request_fn+0x3f/0x6c0
[ 190.510888] ? kobject_put+0x1f/0x60
[ 190.515305] __blk_run_queue+0x33/0x40
[ 190.519877] blk_start_queue+0x29/0x40
[ 190.524438] scsi_start_queue+0x40/0x60
[ 190.529081] __scsi_remove_device+0x4d/0xe0
[ 190.534079] scsi_forget_host+0x60/0x70
[ 190.538738] scsi_remove_host+0x77/0x110
[ 190.543462] srp_remove_work+0x90/0x230 [ib_srp]
Regards,
Israel.
