Commit 5c10e63c authored Apr 29, 2009 by Takahiro Yasui Committed by James Bottomley May 23, 2009

[SCSI] limit state transitions in scsi_internal_device_unblock



scsi timeout on two or more devices may cause extremely long execution
time for user applications because SDEV_OFFLINE state is changed to
SDEV_RUNNING state during scsi error recovery procedures triggered by
a bus reset or a host reset of scsi LLD, and scsi timeout can happens
on the same devices many times.

This happens because scsi_internal_device_unblock() changes device's
state to SDEV_RUNNING even if a device in other states than SDEV_BLOCK,
while the following two transitions are required in this function.

  SDEV_BLOCK -> SDEV_RUNNING
  SDEV_CREATED_BLOCK -> SDEV_CREATED

Otherwise, it returns -EINVAL.

Signed-off-by: Takahiro Yasui <tyasui@redhat.com>
[matthew@wil.cx: supplied rewritten base for patch]
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

parent b0d428ad

drivers/scsi/scsi_lib.c

+6 −8

Original line number	Diff line number	Diff line
		@@ -2441,20 +2441,18 @@ int
		scsi_internal_device_unblock(struct scsi_device *sdev)
		{
		struct request_queue *q = sdev->request_queue;
		int err;
		unsigned long flags;

		/*
		* Try to transition the scsi device to SDEV_RUNNING
		* and goose the device queue if successful.
		*/
		err = scsi_device_set_state(sdev, SDEV_RUNNING);
		if (err) {
		err = scsi_device_set_state(sdev, SDEV_CREATED);

		if (err)
		return err;
		}
		if (sdev->sdev_state == SDEV_BLOCK)
		sdev->sdev_state = SDEV_RUNNING;
		else if (sdev->sdev_state == SDEV_CREATED_BLOCK)
		sdev->sdev_state = SDEV_CREATED;
		else
		return -EINVAL;

		spin_lock_irqsave(q->queue_lock, flags);
		blk_start_queue(q);