From: Martin Wilck <mwilck@xxxxxxxx> Since the might_sleep() annotation was added in scsi_device_put() and alua_rtpg_queue(), we have seen repeated reports of "BUG: sleeping function called from invalid context" [1], [2]. alua_rtpg_queue() is always called from contexts where the caller must hold at least one reference to the scsi device in question. This means that the reference taken by alua_rtpg_queue() itself can't be the last one, and thus can be dropped without entering the code path in which scsi_device_put() might actually sleep. Add a new helper function, scsi_device_put_nosleep() for cases like this, where a device reference is put from atomic context, and at the same time it is certain that this reference is not the last one, and use it from alua_rtpg_queue(). [1] https://lore.kernel.org/linux-scsi/b49e37d5-edfb-4c56-3eeb-62c7d5855c00@xxxxxxxxxxxxx/ [2] https://lore.kernel.org/linux-scsi/55c35e64-a7d4-9072-46fd-e8eae6a90e96@xxxxxxxxxxxxx/ Fixes: f93ed747e2c7 ("scsi: core: Release SCSI devices synchronously") Cc: Bart Van Assche <bvanassche@xxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxx> Cc: Sachin Sant <sachinp@xxxxxxxxxxxxx> Cc: Benjamin Block <bblock@xxxxxxxxxxxxx> Reported-by: Steffen Maier <maier@xxxxxxxxxxxxx> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx> ---- Changes v2 -> v3: - clarified the comment on scsi_device_put_nosleep() (Bart van Assche) Changes v1 -> v2: - rebased onto the scsi-fixes branch. - fixed several mistakes pointed out by Steffen Maier. --- drivers/scsi/device_handler/scsi_dh_alua.c | 2 +- drivers/scsi/scsi.c | 24 ++++++++++++++++++---- include/scsi/scsi_device.h | 1 + 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 29a2865b8e2e..8f3aac9e6a50 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -1032,7 +1032,7 @@ static bool alua_rtpg_queue(struct alua_port_group *pg, kref_put(&pg->kref, release_port_group); } if (sdev) - scsi_device_put(sdev); + scsi_device_put_nosleep(sdev); return true; } diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 1426b9b03612..fb7befacd831 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -576,6 +576,25 @@ int scsi_device_get(struct scsi_device *sdev) } EXPORT_SYMBOL(scsi_device_get); +/** + * scsi_device_put_nosleep - release a reference to a scsi_device + * @sdev: device to release a reference on. + * + * Description: Release a reference to the scsi_device and decrements the use + * count of the underlying LLDD module. This function may only be called from + * a call context where it is certain that the reference dropped is not the + * last one. Exception: calling this from scsi_device_put() is legal, because + * scsi_device_put() has a might_sleep() annotation. + */ +void scsi_device_put_nosleep(struct scsi_device *sdev) +{ + struct module *mod = sdev->host->hostt->module; + + put_device(&sdev->sdev_gendev); + module_put(mod); +} +EXPORT_SYMBOL(scsi_device_put_nosleep); + /** * scsi_device_put - release a reference to a scsi_device * @sdev: device to release a reference on. @@ -586,12 +605,9 @@ EXPORT_SYMBOL(scsi_device_get); */ void scsi_device_put(struct scsi_device *sdev) { - struct module *mod = sdev->host->hostt->module; - might_sleep(); - put_device(&sdev->sdev_gendev); - module_put(mod); + scsi_device_put_nosleep(sdev); } EXPORT_SYMBOL(scsi_device_put); diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 3642b8e3928b..f1ad48c9c601 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -365,6 +365,7 @@ void scsi_attach_vpd(struct scsi_device *sdev); extern struct scsi_device *scsi_device_from_queue(struct request_queue *q); extern int __must_check scsi_device_get(struct scsi_device *); +void scsi_device_put_nosleep(struct scsi_device *sdev); extern void scsi_device_put(struct scsi_device *); extern struct scsi_device *scsi_device_lookup(struct Scsi_Host *, uint, uint, u64); -- 2.39.0
