Fix a few race conditions that can be triggered by removing a device:
- Fix a race between starved list processing and device removal.
- Avoid that a SCSI LLD callback can get invoked after
scsi_remove_host() finished.
- Speed up device removal by stopping error handling as soon as
the SHOST_DEL or SHOST_DEL_RECOVERY state has been reached.
- Save and restore the host_scribble field during error handling
These patches have been tested on top of kernel v3.8-rc6 and are also
available here:
http://github.com/bvanassche/linux/tree/device-removal-fixes.
Sorry for the delay between v7 and v8 - the past few weeks were really
hectic.
Changes compared to v7:
- Addressed the review comments posted by Hannes Reinecke and Rolf Eike
Beer.
- Modified patch "Make scsi_remove_host() wait until error handling
finished" such that it is also safe for SCSI timeout values below
the maximum LLD response time by modifying scsi_send_eh_cmnd() such
that it does not invoke any LLD code after scsi_remove_host() started.
- Added a patch to save and restore the host_scribble field.
- Refined / clarified several patch descriptions.
- Rebased and retested on top of kernel v3.8-rc6.
Changes compared to v6:
- Dropped the first six patches since Jens queued these for 3.8.
- Added patch to avoid that __scsi_remove_device() is invoked twice.
- Restore error recovery in the SHOST_CANCEL state.
Changes compared to v5:
- Avoid that block layer work can be scheduled on a dead queue.
- Do not invoke any SCSI LLD callback after scsi_remove_host() finished.
- Stop error handling as soon as scsi_remove_host() started.
- Remove the unused function bsg_goose_queue().
- Avoid that scsi_device_set_state() triggers a race condition.
Changes compared to v4:
- Moved queue_flag_set(QUEUE_FLAG_DEAD, q) from blk_drain_queue() into
blk_cleanup_queue().
- Declared the new __blk_run_queue_uncond() function inline. Checked in
the generated assembler code that this function is really inlined in
__blk_run_queue().
- Elaborated several patch descriptions.
- Added sparse annotations to scsi_request_fn().
- Split several patches.
Changes compared to v3:
- Fixed a race condition by setting QUEUE_FLAG_DEAD earlier.
- Added a patch for fixing a race between starved list processing
and device removal to this series.
Changes compared to v2:
- Split second patch into two patches.
- Refined patch descriptions.
Changes compared to v1:
- Included a patch to rename QUEUE_FLAG_DEAD.
- Refined the descriptions of the __blk_run_queue_uncond() and
blk_cleanup_queue() functions.
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