Although the power management code never calls the system-wide and runtime suspend callbacks concurrently, runtime power state changes can happen while the system is being suspended or resumed. See also the dpm_suspend() and dpm_resume() calls in hibernation_snapshot(). Make sure the sd driver supports this. This patch avoids that the following call trace is reported during system-wide suspend:

WARNING: CPU: 0 PID: 701 at drivers/scsi/scsi_lib.c:3047 scsi_device_quiesce+0x4b/0xd0 Workqueue: events_unbound async_run_entry_fn RIP: 0010:scsi_device_quiesce+0x4b/0xd0 Call Trace: scsi_bus_suspend_common+0x71/0xe0 scsi_bus_freeze+0x15/0x20 dpm_run_callback+0x88/0x360 __device_suspend+0x1c4/0x840 async_suspend+0x1f/0xb0 async_run_entry_fn+0x6e/0x2c0 process_one_work+0x4ae/0xa20 worker_thread+0x63/0x5a0 kthread+0x1cf/0x1f0 ret_from_fork+0x24/0x30

Fixes: cd84a62e0078 ("block, scsi: Change the preempt-only flag into a counter") Cc: Lee Duncan lduncan@suse.com Cc: Hannes Reinecke hare@suse.com Cc: Luis Chamberlain mcgrof@kernel.org Cc: Johannes Thumshirn jthumshirn@suse.de Cc: Christoph Hellwig hch@lst.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Dan Williams dan.j.williams@intel.com Cc: stable@vger.kernel.org Signed-off-by: Bart Van Assche bvanassche@acm.org --- drivers/scsi/scsi_lib.c | 15 ++++++--------- include/scsi/scsi_device.h | 1 - 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 7db3c5fae469..6c18a61176e5 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -3052,11 +3052,12 @@ scsi_device_quiesce(struct scsi_device *sdev) int err;

/* - * It is allowed to call scsi_device_quiesce() multiple times from - * the same context but concurrent scsi_device_quiesce() calls are - * not allowed. + * Since all scsi_device_quiesce() and scsi_device_resume() calls + * are serialized it is safe here to check the device state without + * holding the SCSI device state mutex. */ - WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current); + if (sdev->sdev_state == SDEV_QUIESCE) + return 0;

blk_set_preempt_only(q);

@@ -3072,9 +3073,7 @@ scsi_device_quiesce(struct scsi_device *sdev)

mutex_lock(&sdev->state_mutex); err = scsi_device_set_state(sdev, SDEV_QUIESCE); - if (err == 0) - sdev->quiesced_by = current; - else + if (err) blk_clear_preempt_only(q); mutex_unlock(&sdev->state_mutex);

@@ -3098,8 +3097,6 @@ void scsi_device_resume(struct scsi_device *sdev) * device deleted during suspend) */ mutex_lock(&sdev->state_mutex); - WARN_ON_ONCE(!sdev->quiesced_by); - sdev->quiesced_by = NULL; blk_clear_preempt_only(sdev->request_queue); if (sdev->sdev_state == SDEV_QUIESCE) scsi_device_set_state(sdev, SDEV_RUNNING); diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 202f4d6a4342..ef86c8adc5d5 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -226,7 +226,6 @@ struct scsi_device { unsigned char access_state; struct mutex state_mutex; enum scsi_device_state sdev_state; - struct task_struct *quiesced_by; unsigned long sdev_data[0]; } __attribute__((aligned(sizeof(unsigned long))));