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authorBart Van Assche <bart.vanassche@sandisk.com>2017-06-02 23:21:53 +0200
committerMartin K. Petersen <martin.petersen@oracle.com>2017-06-13 02:55:58 +0200
commit551eb598e5ea52996eb821f43740496a78a97b68 (patch)
treefe57f0a626a83e9e2d1d183168df1306c201e90c /drivers/scsi/scsi_lib.c
parentscsi: Avoid that scsi_exit_rq() triggers a use-after-free (diff)
downloadlinux-551eb598e5ea52996eb821f43740496a78a97b68.tar.xz
linux-551eb598e5ea52996eb821f43740496a78a97b68.zip
scsi: Split scsi_internal_device_block()
Instead of passing a "wait" argument to scsi_internal_device_block(), split this function into a function that waits and a function that doesn't wait. This will make it easier to serialize SCSI device state changes through a mutex. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Sreekanth Reddy <sreekanth.reddy@broadcom.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c73
1 files changed, 47 insertions, 26 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a95eb022fb89..fc8f394eb854 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2944,28 +2944,20 @@ scsi_target_resume(struct scsi_target *starget)
EXPORT_SYMBOL(scsi_target_resume);
/**
- * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
- * @sdev: device to block
- * @wait: Whether or not to wait until ongoing .queuecommand() /
- * .queue_rq() calls have finished.
+ * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
+ * @sdev: device to block
*
- * Block request made by scsi lld's to temporarily stop all
- * scsi commands on the specified device. May sleep.
+ * Pause SCSI command processing on the specified device. Does not sleep.
*
- * Returns zero if successful or error if not
+ * Returns zero if successful or a negative error code upon failure.
*
- * Notes:
- * This routine transitions the device to the SDEV_BLOCK state
- * (which must be a legal transition). When the device is in this
- * state, all commands are deferred until the scsi lld reenables
- * the device with scsi_device_unblock or device_block_tmo fires.
- *
- * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
- * scsi_internal_device_block() has blocked a SCSI device and also
- * remove the rport mutex lock and unlock calls from srp_queuecommand().
+ * Notes:
+ * This routine transitions the device to the SDEV_BLOCK state (which must be
+ * a legal transition). When the device is in this state, command processing
+ * is paused until the device leaves the SDEV_BLOCK state. See also
+ * scsi_internal_device_unblock_nowait().
*/
-int
-scsi_internal_device_block(struct scsi_device *sdev, bool wait)
+int scsi_internal_device_block_nowait(struct scsi_device *sdev)
{
struct request_queue *q = sdev->request_queue;
unsigned long flags;
@@ -2985,21 +2977,50 @@ scsi_internal_device_block(struct scsi_device *sdev, bool wait)
* request queue.
*/
if (q->mq_ops) {
- if (wait)
- blk_mq_quiesce_queue(q);
- else
- blk_mq_stop_hw_queues(q);
+ blk_mq_stop_hw_queues(q);
} else {
spin_lock_irqsave(q->queue_lock, flags);
blk_stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
- if (wait)
- scsi_wait_for_queuecommand(sdev);
}
return 0;
}
-EXPORT_SYMBOL_GPL(scsi_internal_device_block);
+EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
+
+/**
+ * scsi_internal_device_block - try to transition to the SDEV_BLOCK state
+ * @sdev: device to block
+ *
+ * Pause SCSI command processing on the specified device and wait until all
+ * ongoing scsi_request_fn() / scsi_queue_rq() calls have finished. May sleep.
+ *
+ * Returns zero if successful or a negative error code upon failure.
+ *
+ * Note:
+ * This routine transitions the device to the SDEV_BLOCK state (which must be
+ * a legal transition). When the device is in this state, command processing
+ * is paused until the device leaves the SDEV_BLOCK state. See also
+ * scsi_internal_device_unblock().
+ *
+ * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
+ * scsi_internal_device_block() has blocked a SCSI device and also
+ * remove the rport mutex lock and unlock calls from srp_queuecommand().
+ */
+static int scsi_internal_device_block(struct scsi_device *sdev)
+{
+ struct request_queue *q = sdev->request_queue;
+ int err;
+
+ err = scsi_internal_device_block_nowait(sdev);
+ if (err == 0) {
+ if (q->mq_ops)
+ blk_mq_quiesce_queue(q);
+ else
+ scsi_wait_for_queuecommand(sdev);
+ }
+ return err;
+}
/**
* scsi_internal_device_unblock - resume a device after a block request
@@ -3056,7 +3077,7 @@ EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
static void
device_block(struct scsi_device *sdev, void *data)
{
- scsi_internal_device_block(sdev, true);
+ scsi_internal_device_block(sdev);
}
static int