github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-07 06:17:02 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

scsi: ufs: core: Fix a deadlock between clock scaling and device commands

Browse Source 
Since commit 08b12cda6c ("scsi: ufs: core: Switch to
scsi_get_internal_cmd()"), device management commands go through
blk_execute_rq() on the pseudo SCSI device, which shares the tagset with
the logical units, while ufshcd_dev_man_lock() holds clk_scaling_lock for
reading.

ufshcd_clock_scaling_prepare() and ufshcd_pause_command_processing()
quiesce the tagset before taking clk_scaling_lock for writing. A device
management command holding the lock for reading at that point is never
dispatched and never times out, so the writer waits forever with all
logical units quiesced. On a Lenovo Legion Tab Y700 Gen 5 this ended in a
hung task panic.

Take clk_scaling_lock before quiescing the tagset, and in
ufshcd_clock_scaling_prepare() also wb_mutex, which is always taken before
clk_scaling_lock. Release them in the reverse order. Commit b52d695d06
("scsi: ufs: core: Keep internal commands dispatchable during error
handling") fixed the same problem in the error handler.

Fixes: 08b12cda6c ("scsi: ufs: core: Switch to scsi_get_internal_cmd()")
Fixes: dc5dcac532 ("scsi: ufs: core: Add helpers to pause and resume command processing")
Cc: stable@vger.kernel.org
Signed-off-by: Joonhoe Kim <26rote@gmail.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Link: https://patch.msgid.link/20261016124608.46-1-26rote@gmail.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
This commit is contained in:
Joonhoe Kim 2026-10-16 21:46:08 +09:00 committed by Martin K. Petersen (Oracle)
parent 1b39bd7b82
commit 2327df6d2a
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/ufs/core/ufshcd.c
View File

@ -1360,13 +1360,13 @@ int ufshcd_pause_command_processing(struct ufs_hba *hba, u64 timeout_us)
int ret = 0;
mutex_lock(&hba->host->scan_mutex);
blk_mq_quiesce_tagset(&hba->host->tag_set);
down_write(&hba->clk_scaling_lock);
blk_mq_quiesce_tagset(&hba->host->tag_set);
if (ufshcd_wait_for_pending_cmds(hba, timeout_us)) {
ret = -EBUSY;
up_write(&hba->clk_scaling_lock);
blk_mq_unquiesce_tagset(&hba->host->tag_set);
up_write(&hba->clk_scaling_lock);
mutex_unlock(&hba->host->scan_mutex);
}
@ -1383,8 +1383,8 @@ void ufshcd_resume_command_processing(struct ufs_hba *hba)
__releases(&hba->clk_scaling_lock)
__releases(&hba->host->scan_mutex)
{
up_write(&hba->clk_scaling_lock);
blk_mq_unquiesce_tagset(&hba->host->tag_set);
up_write(&hba->clk_scaling_lock);
mutex_unlock(&hba->host->scan_mutex);
}
@ -1461,16 +1461,16 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba, u64 timeout_us)
* clock scaling is in progress
*/
mutex_lock(&hba->host->scan_mutex);
blk_mq_quiesce_tagset(&hba->host->tag_set);
mutex_lock(&hba->wb_mutex);
down_write(&hba->clk_scaling_lock);
blk_mq_quiesce_tagset(&hba->host->tag_set);
if (!hba->clk_scaling.is_allowed ||
ufshcd_wait_for_pending_cmds(hba, timeout_us)) {
ret = -EBUSY;
blk_mq_unquiesce_tagset(&hba->host->tag_set);
up_write(&hba->clk_scaling_lock);
mutex_unlock(&hba->wb_mutex);
blk_mq_unquiesce_tagset(&hba->host->tag_set);
mutex_unlock(&hba->host->scan_mutex);
goto out;
}
@ -1487,9 +1487,9 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err)
__releases(&hba->wb_mutex)
__releases(&hba->host->scan_mutex)
{
blk_mq_unquiesce_tagset(&hba->host->tag_set);
up_write(&hba->clk_scaling_lock);
mutex_unlock(&hba->wb_mutex);
blk_mq_unquiesce_tagset(&hba->host->tag_set);
mutex_unlock(&hba->host->scan_mutex);
/* Enable Write Booster if current gear requires it else disable it */