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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id l123sm583569pgl.24.2020.08.30.19.54.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 30 Aug 2020 19:54:13 -0700 (PDT) From: Bart Van Assche To: Alan Stern Cc: linux-scsi@vger.kernel.org, Martin Kepplinger , Can Guo , Bart Van Assche Subject: [PATCH RFC 5/6] scsi_transport_spi: Freeze request queues instead of quiescing Date: Sun, 30 Aug 2020 19:53:56 -0700 Message-Id: <20200831025357.32700-6-bvanassche@acm.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200831025357.32700-1-bvanassche@acm.org> References: <20200831025357.32700-1-bvanassche@acm.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Instead of quiescing the request queues involved in domain validation, freeze these. As a result, the struct request_queue pm_only member is no longer set during domain validation. That will allow to modify scsi_execute() such that it stops setting the BLK_MQ_REQ_PREEMPT flag. Three additional changes in this patch are that scsi_mq_alloc_queue() is exported, that scsi_device_quiesce() is no longer exported and that scsi_target_{quiesce,resume}() have been changed into scsi_target_{freeze,unfreeze}(). Signed-off-by: Bart Van Assche --- drivers/scsi/scsi_lib.c | 22 ++++++------ drivers/scsi/scsi_priv.h | 2 ++ drivers/scsi/scsi_transport_spi.c | 56 ++++++++++++++++++++----------- include/scsi/scsi_device.h | 6 ++-- 4 files changed, 51 insertions(+), 35 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1d7135f61962..49eb8f2dffd8 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1866,6 +1866,7 @@ struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev) blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, sdev->request_queue); return sdev->request_queue; } +EXPORT_SYMBOL_GPL(scsi_mq_alloc_queue); int scsi_mq_setup_tags(struct Scsi_Host *shost) { @@ -2540,7 +2541,6 @@ scsi_device_quiesce(struct scsi_device *sdev) return err; } -EXPORT_SYMBOL(scsi_device_quiesce); /** * scsi_device_resume - Restart user issued commands to a quiesced device. @@ -2569,30 +2569,30 @@ void scsi_device_resume(struct scsi_device *sdev) EXPORT_SYMBOL(scsi_device_resume); static void -device_quiesce_fn(struct scsi_device *sdev, void *data) +device_freeze_fn(struct scsi_device *sdev, void *data) { - scsi_device_quiesce(sdev); + blk_mq_freeze_queue(sdev->request_queue); } void -scsi_target_quiesce(struct scsi_target *starget) +scsi_target_freeze(struct scsi_target *starget) { - starget_for_each_device(starget, NULL, device_quiesce_fn); + starget_for_each_device(starget, NULL, device_freeze_fn); } -EXPORT_SYMBOL(scsi_target_quiesce); +EXPORT_SYMBOL(scsi_target_freeze); static void -device_resume_fn(struct scsi_device *sdev, void *data) +device_unfreeze_fn(struct scsi_device *sdev, void *data) { - scsi_device_resume(sdev); + blk_mq_unfreeze_queue(sdev->request_queue); } void -scsi_target_resume(struct scsi_target *starget) +scsi_target_unfreeze(struct scsi_target *starget) { - starget_for_each_device(starget, NULL, device_resume_fn); + starget_for_each_device(starget, NULL, device_unfreeze_fn); } -EXPORT_SYMBOL(scsi_target_resume); +EXPORT_SYMBOL(scsi_target_unfreeze); /** * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h index d12ada035961..6b9203df84c8 100644 --- a/drivers/scsi/scsi_priv.h +++ b/drivers/scsi/scsi_priv.h @@ -95,6 +95,8 @@ extern int scsi_mq_setup_tags(struct Scsi_Host *shost); extern void scsi_mq_destroy_tags(struct Scsi_Host *shost); extern void scsi_exit_queue(void); extern void scsi_evt_thread(struct work_struct *work); +extern int scsi_device_quiesce(struct scsi_device *sdev); +extern void scsi_device_resume(struct scsi_device *sdev); struct request_queue; struct request; diff --git a/drivers/scsi/scsi_transport_spi.c b/drivers/scsi/scsi_transport_spi.c index 959990f66865..63bec8980b27 100644 --- a/drivers/scsi/scsi_transport_spi.c +++ b/drivers/scsi/scsi_transport_spi.c @@ -997,59 +997,75 @@ void spi_dv_device(struct scsi_device *sdev) { struct scsi_target *starget = sdev->sdev_target; + struct request_queue *q1, *q2; u8 *buffer; const int len = SPI_MAX_ECHO_BUFFER_SIZE*2; /* - * Because this function and the power management code both call - * scsi_device_quiesce(), it is not safe to perform domain validation - * while suspend or resume is in progress. Hence the - * lock/unlock_system_sleep() calls. + * Because creates a new request queue that is not visible to the rest + * of the system, domain validation must be serialized against suspend, + * resume and runtime power management. Hence the + * lock/unlock_system_sleep() and scsi_autopm_{get,put}_device() calls. */ lock_system_sleep(); + if (scsi_autopm_get_device(sdev)) + goto unlock_system_sleep; + if (unlikely(spi_dv_in_progress(starget))) - goto unlock; + goto put_autopm; if (unlikely(scsi_device_get(sdev))) - goto unlock; + goto put_autopm; spi_dv_in_progress(starget) = 1; buffer = kzalloc(len, GFP_KERNEL); if (unlikely(!buffer)) - goto out_put; - - /* We need to verify that the actual device will quiesce; the - * later target quiesce is just a nice to have */ - if (unlikely(scsi_device_quiesce(sdev))) - goto out_free; - - scsi_target_quiesce(starget); + goto put_sdev; spi_dv_pending(starget) = 1; mutex_lock(&spi_dv_mutex(starget)); starget_printk(KERN_INFO, starget, "Beginning Domain Validation\n"); - spi_dv_device_internal(sdev, sdev->request_queue, buffer); + /* + * Save the request queue pointer before it is overwritten by + * scsi_mq_alloc_queue(). + */ + q1 = sdev->request_queue; + q2 = scsi_mq_alloc_queue(sdev); + + if (q2) { + /* + * Restore the request queue pointer such that no other + * subsystem can submit SCSI commands to 'sdev'. + */ + sdev->request_queue = q1; + scsi_target_freeze(starget); + spi_dv_device_internal(sdev, q2, buffer); + blk_cleanup_queue(q2); + scsi_target_unfreeze(starget); + } starget_printk(KERN_INFO, starget, "Ending Domain Validation\n"); mutex_unlock(&spi_dv_mutex(starget)); spi_dv_pending(starget) = 0; - scsi_target_resume(starget); - spi_initial_dv(starget) = 1; - out_free: kfree(buffer); - out_put: + +put_sdev: spi_dv_in_progress(starget) = 0; scsi_device_put(sdev); -unlock: + +put_autopm: + scsi_autopm_put_device(sdev); + +unlock_system_sleep: unlock_system_sleep(); } EXPORT_SYMBOL(spi_dv_device); diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index ef6e96e12c7c..08f88ef04bc9 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -422,10 +422,8 @@ extern struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type, extern void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt); extern void sdev_evt_send_simple(struct scsi_device *sdev, enum scsi_device_event evt_type, gfp_t gfpflags); -extern int scsi_device_quiesce(struct scsi_device *sdev); -extern void scsi_device_resume(struct scsi_device *sdev); -extern void scsi_target_quiesce(struct scsi_target *); -extern void scsi_target_resume(struct scsi_target *); +extern void scsi_target_freeze(struct scsi_target *); +extern void scsi_target_unfreeze(struct scsi_target *); extern void scsi_scan_target(struct device *parent, unsigned int channel, unsigned int id, u64 lun, enum scsi_scan_mode rescan);