During system resume, scsi_resume_device() decreases a request queue's
pm_only counter if the scsi device was quiesced before. But after that,
if the scsi device's RPM status is RPM_SUSPENDED, the pm_only counter is
still held (non-zero). Current scsi resume hook only sets the RPM status
of the scsi device and its request queue to RPM_ACTIVE, but leaves the
pm_only counter unchanged. This may make the request queue's pm_only
counter remain non-zero after resume hook returns, hence those who are
waiting on the mq_freeze_wq would never be woken up. Fix this by calling
blk_post_runtime_resume() if pm_only is non-zero to balance the pm_only
counter which is held by the scsi device's RPM ops.
(struct request_queue)0xFFFFFF815B69E938
pm_only = (counter = 2),
rpm_status = 0,
dev = 0xFFFFFF815B0511A0,
((struct device)0xFFFFFF815B0511A0)).power
is_suspended = FALSE,
runtime_status = RPM_ACTIVE,
(struct scsi_device)0xffffff815b051000
request_queue = 0xFFFFFF815B69E938,
sdev_state = SDEV_RUNNING,
quiesced_by = 0x0,
B::v.f_/task_0xFFFFFF810C246940
-000|__switch_to(prev = 0xFFFFFF810C246940, next = 0xFFFFFF80A49357C0)
-001|context_switch(inline)
-001|__schedule(?)
-002|schedule()
-003|blk_queue_enter(q = 0xFFFFFF815B69E938, flags = 0)
-004|generic_make_request(?)
-005|submit_bio(bio = 0xFFFFFF80A8195B80)
Signed-off-by: Can Guo <[email protected]>
Change since v1:
- Added more debugging context info
---
drivers/scsi/scsi_pm.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index 3717eea..4804029 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -93,8 +93,10 @@ static int scsi_dev_type_resume(struct device *dev,
*/
if (!err && scsi_is_sdev_device(dev)) {
struct scsi_device *sdev = to_scsi_device(dev);
-
- blk_set_runtime_active(sdev->request_queue);
+ if (blk_queue_pm_only(sdev->request_queue))
+ blk_post_runtime_resume(sdev->request_queue, 0);
+ else
+ blk_set_runtime_active(sdev->request_queue);
}
}
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
Loop more...
On 2020-04-14 13:24, Can Guo wrote:
> During system resume, scsi_resume_device() decreases a request queue's
> pm_only counter if the scsi device was quiesced before. But after that,
> if the scsi device's RPM status is RPM_SUSPENDED, the pm_only counter
> is
> still held (non-zero). Current scsi resume hook only sets the RPM
> status
> of the scsi device and its request queue to RPM_ACTIVE, but leaves the
> pm_only counter unchanged. This may make the request queue's pm_only
> counter remain non-zero after resume hook returns, hence those who are
> waiting on the mq_freeze_wq would never be woken up. Fix this by
> calling
> blk_post_runtime_resume() if pm_only is non-zero to balance the pm_only
> counter which is held by the scsi device's RPM ops.
>
> (struct request_queue)0xFFFFFF815B69E938
> pm_only = (counter = 2),
> rpm_status = 0,
> dev = 0xFFFFFF815B0511A0,
>
> ((struct device)0xFFFFFF815B0511A0)).power
> is_suspended = FALSE,
> runtime_status = RPM_ACTIVE,
>
> (struct scsi_device)0xffffff815b051000
> request_queue = 0xFFFFFF815B69E938,
> sdev_state = SDEV_RUNNING,
> quiesced_by = 0x0,
>
> B::v.f_/task_0xFFFFFF810C246940
> -000|__switch_to(prev = 0xFFFFFF810C246940, next = 0xFFFFFF80A49357C0)
> -001|context_switch(inline)
> -001|__schedule(?)
> -002|schedule()
> -003|blk_queue_enter(q = 0xFFFFFF815B69E938, flags = 0)
> -004|generic_make_request(?)
> -005|submit_bio(bio = 0xFFFFFF80A8195B80)
>
> Signed-off-by: Can Guo <[email protected]>
>
> Change since v1:
> - Added more debugging context info
>
> ---
> drivers/scsi/scsi_pm.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
> index 3717eea..4804029 100644
> --- a/drivers/scsi/scsi_pm.c
> +++ b/drivers/scsi/scsi_pm.c
> @@ -93,8 +93,10 @@ static int scsi_dev_type_resume(struct device *dev,
> */
> if (!err && scsi_is_sdev_device(dev)) {
> struct scsi_device *sdev = to_scsi_device(dev);
> -
> - blk_set_runtime_active(sdev->request_queue);
> + if (blk_queue_pm_only(sdev->request_queue))
> + blk_post_runtime_resume(sdev->request_queue, 0);
> + else
> + blk_set_runtime_active(sdev->request_queue);
> }
> }