On 1/6/2014 7:44 AM, Phillip Susi wrote:
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On 12/16/2013 06:30 PM, Phillip Susi wrote:
For some reason, the system hangs on resume if I issue the REQUEST
SENSE command after blk_pre_runtime_suspend. My understanding is
that the REQ_PM flag should make the command process even though
the queue is RPM_SUSPENDING, but it doesn't seem to work. Anyone
have any idea why?
So I found the problem but I'm confused by it. I thought that the
REQ_PM flag was supposed to make sure the request was dispatched even
though the device was still suspended ( or suspending ). It seems
that this is not the case, and only requests with the type set to
REQ_TYPE_PM_RESUME are dispatched during suspend/resume. The
following patch fixes the hang, but I'm not sure why it is needed or
if it is generally appropriate:
Adding Aaron Lu, author of block layer runtime PM.
I have seen similar issue and fixed it by relaxing the rpm_status check
to allow processing of requests while suspended -
diff --git a/block/blk-core.c b/block/blk-core.c
index 6853ef6..f99165b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2140,8 +2140,7 @@ static void blk_account_io_done(struct request *req)
static struct request *blk_pm_peek_request(struct request_queue *q,
struct request *rq)
{
- if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
- (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
+ if (q->dev && q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))
return NULL;
else
return rq;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 7bd7f0d..c5ce50d 100644
- --- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -227,7 +227,9 @@ int scsi_execute(struct scsi_device *sdev, const
unsigned char *cmd,
req->sense_len = 0;
req->retries = retries;
req->timeout = timeout;
- - req->cmd_type = REQ_TYPE_BLOCK_PC;
+ if (flags & REQ_PM)
+ req->cmd_type = REQ_TYPE_PM_RESUME;
+ else req->cmd_type = REQ_TYPE_BLOCK_PC;
req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
/*
--
Regards,
Sujit
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