Re: [PATCH v6 08/12] block, scsi: Introduce blk_pm_runtime_exit()
On Mon, 2018-08-13 at 17:24 +0800, jianchao.wang wrote: > I'm afraid this will not work. Since this patch fixes a bug that nobody has reported so far and since no later patches rely on this patch, I will leave it out. Thanks, Bart.
Re: [PATCH v6 08/12] block, scsi: Introduce blk_pm_runtime_exit()
Hi Bart
On 08/11/2018 12:17 AM, Bart Van Assche wrote:
> void blk_pm_runtime_exit(struct request_queue *q)
> {
> if (!q->dev)
> return;
>
> pm_runtime_get_sync(q->dev);
> blk_freeze_queue(q);
> q->dev = NULL;
> blk_unfreeze_queue(q);
> }
I'm afraid this will not work.
In following patch:
@@ -972,6 +972,8 @@ int blk_queue_enter(struct request_queue *q,
blk_mq_req_flags_t flags)
if (success)
return 0;
+ blk_pm_request_resume(q);
+
if (flags & BLK_MQ_REQ_NOWAIT)
return -EBUSY;
We could still invoke blk_pm_request_resume even if the queue is frozen.
And we have blk_pm_request_resume later as following:
+static inline void blk_pm_request_resume(struct request_queue *q)
+{
+ if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
+ q->rpm_status == RPM_SUSPENDING))
+ pm_request_resume(q->dev);
+}
Thanks
Jianchao
Re: [PATCH v6 08/12] block, scsi: Introduce blk_pm_runtime_exit()
On Fri, 2018-08-10 at 15:27 +, Bart Van Assche wrote:
> On Fri, 2018-08-10 at 10:39 +0800, jianchao.wang wrote:
> > On 08/10/2018 03:41 AM, Bart Van Assche wrote:
> > > +void blk_pm_runtime_exit(struct request_queue *q)
> > > +{
> > > + if (!q->dev)
> > > + return;
> > > +
> > > + pm_runtime_get_sync(q->dev);
> > > + q->dev = NULL;
> > > +}
> > > +EXPORT_SYMBOL(blk_pm_runtime_exit);
> > > +
> > > /**
> > > * blk_pre_runtime_suspend - Pre runtime suspend check
> > > * @q: the queue of the device
> > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> > > index 69ab459abb98..5537762dfcfd 100644
> > > --- a/drivers/scsi/sd.c
> > > +++ b/drivers/scsi/sd.c
> > > @@ -3420,12 +3420,11 @@ static int sd_probe(struct device *dev)
> > > **/
> > > static int sd_remove(struct device *dev)
> > > {
> > > - struct scsi_disk *sdkp;
> > > - dev_t devt;
> > > + struct scsi_disk *sdkp = dev_get_drvdata(dev);
> > > + struct scsi_device *sdp = sdkp->device;
> > > + dev_t devt = disk_devt(sdkp->disk);
> > >
> > > - sdkp = dev_get_drvdata(dev);
> > > - devt = disk_devt(sdkp->disk);
> > > - scsi_autopm_get_device(sdkp->device);
> > > + blk_pm_runtime_exit(sdp->request_queue)
> >
> >
> > Based on __scsi_device_remove, sd_remove will be invoked before
> > blk_cleanup_queue.
> > So it should be not safe that we set the q->dev to NULL here.
> >
> > We have following operations in followed patch:
> > +static inline void blk_pm_mark_last_busy(struct request *rq)
> > +{
> > + if (rq->q->dev && !(rq->rq_flags & RQF_PM))
> > + pm_runtime_mark_last_busy(rq->q->dev);
> > +}
>
> How about moving the blk_pm_runtime_exit() call into blk_cleanup_queue() at
> a point where it is sure that there are no requests in progress? That should
> avoid that blk_pm_mark_last_busy() races against blk_pm_runtime_exit().
That wouldn't work because unbinding the SCSI ULD doesn't remove the request
queue. How about changing blk_pm_runtime_exit() into something like the
following?
void blk_pm_runtime_exit(struct request_queue *q)
{
if (!q->dev)
return;
pm_runtime_get_sync(q->dev);
blk_freeze_queue(q);
q->dev = NULL;
blk_unfreeze_queue(q);
}
Bart.
Re: [PATCH v6 08/12] block, scsi: Introduce blk_pm_runtime_exit()
On Fri, 2018-08-10 at 10:39 +0800, jianchao.wang wrote:
> On 08/10/2018 03:41 AM, Bart Van Assche wrote:
> > +void blk_pm_runtime_exit(struct request_queue *q)
> > +{
> > + if (!q->dev)
> > + return;
> > +
> > + pm_runtime_get_sync(q->dev);
> > + q->dev = NULL;
> > +}
> > +EXPORT_SYMBOL(blk_pm_runtime_exit);
> > +
> > /**
> > * blk_pre_runtime_suspend - Pre runtime suspend check
> > * @q: the queue of the device
> > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> > index 69ab459abb98..5537762dfcfd 100644
> > --- a/drivers/scsi/sd.c
> > +++ b/drivers/scsi/sd.c
> > @@ -3420,12 +3420,11 @@ static int sd_probe(struct device *dev)
> > **/
> > static int sd_remove(struct device *dev)
> > {
> > - struct scsi_disk *sdkp;
> > - dev_t devt;
> > + struct scsi_disk *sdkp = dev_get_drvdata(dev);
> > + struct scsi_device *sdp = sdkp->device;
> > + dev_t devt = disk_devt(sdkp->disk);
> >
> > - sdkp = dev_get_drvdata(dev);
> > - devt = disk_devt(sdkp->disk);
> > - scsi_autopm_get_device(sdkp->device);
> > + blk_pm_runtime_exit(sdp->request_queue)
>
>
> Based on __scsi_device_remove, sd_remove will be invoked before
> blk_cleanup_queue.
> So it should be not safe that we set the q->dev to NULL here.
>
> We have following operations in followed patch:
> +static inline void blk_pm_mark_last_busy(struct request *rq)
> +{
> + if (rq->q->dev && !(rq->rq_flags & RQF_PM))
> + pm_runtime_mark_last_busy(rq->q->dev);
> +}
Hello Jianchao,
How about moving the blk_pm_runtime_exit() call into blk_cleanup_queue() at
a point where it is sure that there are no requests in progress? That should
avoid that blk_pm_mark_last_busy() races against blk_pm_runtime_exit().
Thanks,
Bart.
[PATCH v6 08/12] block, scsi: Introduce blk_pm_runtime_exit()
Since it is possible to unbind a SCSI ULD and since unbinding
removes the association between a request queue and struct device,
the q->dev pointer has to be reset during unbind. Hence introduce
a function in the block layer that clears request_queue.dev.
Signed-off-by: Bart Van Assche
Cc: Martin K. Petersen
Cc: Christoph Hellwig
Cc: Ming Lei
Cc: Jianchao Wang
Cc: Hannes Reinecke
Cc: Johannes Thumshirn
Cc: Alan Stern
---
block/blk-pm.c | 18 ++
drivers/scsi/sd.c | 9 -
drivers/scsi/sr.c | 3 ++-
include/linux/blk-pm.h | 2 ++
4 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/block/blk-pm.c b/block/blk-pm.c
index 9b636960d285..bf8532da952d 100644
--- a/block/blk-pm.c
+++ b/block/blk-pm.c
@@ -40,6 +40,24 @@ void blk_pm_runtime_init(struct request_queue *q, struct
device *dev)
}
EXPORT_SYMBOL(blk_pm_runtime_init);
+/**
+ * blk_pm_runtime_exit - runtime PM exit routine
+ * @q: the queue of the device
+ *
+ * This function should be called from the device_driver.remove() callback
+ * function to avoid that further calls to runtime power management functions
+ * occur.
+ */
+void blk_pm_runtime_exit(struct request_queue *q)
+{
+ if (!q->dev)
+ return;
+
+ pm_runtime_get_sync(q->dev);
+ q->dev = NULL;
+}
+EXPORT_SYMBOL(blk_pm_runtime_exit);
+
/**
* blk_pre_runtime_suspend - Pre runtime suspend check
* @q: the queue of the device
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 69ab459abb98..5537762dfcfd 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3420,12 +3420,11 @@ static int sd_probe(struct device *dev)
**/
static int sd_remove(struct device *dev)
{
- struct scsi_disk *sdkp;
- dev_t devt;
+ struct scsi_disk *sdkp = dev_get_drvdata(dev);
+ struct scsi_device *sdp = sdkp->device;
+ dev_t devt = disk_devt(sdkp->disk);
- sdkp = dev_get_drvdata(dev);
- devt = disk_devt(sdkp->disk);
- scsi_autopm_get_device(sdkp->device);
+ blk_pm_runtime_exit(sdp->request_queue);
async_synchronize_full_domain(_sd_pm_domain);
async_synchronize_full_domain(_sd_probe_domain);
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index de4413e66eca..476987f7ed48 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -1002,8 +1002,9 @@ static void sr_kref_release(struct kref *kref)
static int sr_remove(struct device *dev)
{
struct scsi_cd *cd = dev_get_drvdata(dev);
+ struct scsi_device *sdev = cd->device;
- scsi_autopm_get_device(cd->device);
+ blk_pm_runtime_exit(sdev->request_queue);
del_gendisk(cd->disk);
dev_set_drvdata(dev, NULL);
diff --git a/include/linux/blk-pm.h b/include/linux/blk-pm.h
index b80c65aba249..6d654f41acbf 100644
--- a/include/linux/blk-pm.h
+++ b/include/linux/blk-pm.h
@@ -11,6 +11,7 @@ struct request_queue;
*/
#ifdef CONFIG_PM
extern void blk_pm_runtime_init(struct request_queue *q, struct device *dev);
+extern void blk_pm_runtime_exit(struct request_queue *q);
extern int blk_pre_runtime_suspend(struct request_queue *q);
extern void blk_post_runtime_suspend(struct request_queue *q, int err);
extern void blk_pre_runtime_resume(struct request_queue *q);
@@ -19,6 +20,7 @@ extern void blk_set_runtime_active(struct request_queue *q);
#else
static inline void blk_pm_runtime_init(struct request_queue *q,
struct device *dev) {}
+static inline void blk_pm_runtime_exit(struct request_queue *q) {}
#endif
#endif /* _BLK_PM_H_ */
--
2.18.0
