shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-07 03:15:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

FROMLIST: scsi: ufs: Fix deadlocks between power management and error handler

Browse Source 
The following deadlocks have been observed on multiple test setups:

* ufshcd_wl_suspend() is waiting for blk_execute_rq() to complete while it
  holds host_sem.
* ufshcd_eh_host_reset_handler() invokes ufshcd_err_handler() and the
  latter function tries to obtain host_sem.
This is a deadlock because blk_execute_rq() can't execute SCSI commands
while the host is in the SHOST_RECOVERY state and because the error
handler cannot make progress either.

* ufshcd_wl_runtime_resume() is waiting for blk_execute_rq() to finish
  while it holds host_sem.
* ufshcd_eh_host_reset_handler() invokes ufshcd_err_handler() and the
  latter function calls pm_runtime_resume().
This is a deadlock because of the same reason as the previous scenario.

Fix both deadlocks by not obtaining host_sem from the power management
code paths. Removing the host_sem locking from the power management code
is safe because the ufshcd_err_handler() is already serialized against
SCSI command execution.

Cc: dh0421.hwang@samsung.com
Cc: Asutosh Das <asutoshd@codeaurora.org>
Fixes: b294ff3e34 ("scsi: ufs: core: Enable power management for wlun")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Bug: 240498410
Bug: 246990788
Bug: 247073231
Bug: 247081382
Bug: 247082093
Link: https://lore.kernel.org/linux-scsi/
Signed-off-by: Bart Van Assche <bvanassche@google.com>
Change-Id: Ifb9b429ba89ff6d8a133d96a172eaefc09d85955
This commit is contained in:
Bart Van Assche
2022-09-16 06:37:59 -07:00
committed by Bart Van Assche
parent 32934b542c
commit f68d040c31
1 changed files with 1 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/scsi/ufs/ufshcd.c
View File

@@ -9337,16 +9337,13 @@ static int ufshcd_wl_suspend(struct device *dev)
ktime_t start = ktime_get();
hba = shost_priv(sdev->host);
down(&hba->host_sem);
if (pm_runtime_suspended(dev))
goto out;
ret = __ufshcd_wl_suspend(hba, UFS_SYSTEM_PM);
if (ret) {
if (ret)
dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__, ret);
up(&hba->host_sem);
}
out:
if (!ret)
@@ -9379,7 +9376,6 @@ out:
hba->curr_dev_pwr_mode, hba->uic_link_state);
if (!ret)
hba->is_sys_suspended = false;
up(&hba->host_sem);
return ret;
}
#endif