Messages in this thread | | | From | Tejun Heo <> | Subject | [PATCH scsi-misc-2.6 00/04] scsi: misc timer fixes (reworked) | Date | Tue, 19 Apr 2005 23:31:01 +0900 (KST) |
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Hello, James.
This patchset contains the following patches from the previous timer update patchset.
02_scsi_timer_eh_timer_fix.patch 03_scsi_timer_dispatch_race_fix.patch 04_scsi_timer_remove_delete_timer_from_reset_provider.patch
eh_timer_fix is reworked as you suggested and split into two patches. (#01 and #02)
In the current bk repository, aic7xxx_osm.c has been updated to not use scsi_add_timer() but aic79xx_osm.c hasn't been yet. I guess it's gonna be updated sometime soon, so I've dropped the aic7xxx update patch.
As aic79xx_osm.c still uses scsi_add_timer(), timer API update patches are omitted. I'll repost them once aic79xx_osm.c is converted.
dispatch_race_fix and remove_delete_timer_from_reset_provider patches are the same as in the previous posting. If you've already applied them, just ignore those two (#03 and #04).
The following bugs are fixed.
* Race condition between eh and normal completion path for eh_timer * scsi_delete_timer() race in scsi_queue_insert()
[ Start of patch descriptions ]
01_scsi_timer_eh_timer_fix.patch : make scsi_send_eh_cmnd use its own timer instead of scmd->eh_timeout
scmd->eh_timeout is used to resolve the race between command completion and timeout. However, during error handling, scsi_send_eh_cmnd uses scmd->eh_timeout. This creates a race condition between eh and normal completion for a request which has timed out and in the process of error handling. If the request completes while scmd->eh_timeout is being used by eh, eh timeout is lost and the command will be handled by both eh and completion path. This patch fixes the race by making scsi_send_eh_cmnd() use its own timer.
This patch adds shost->eh_timeout field. The name of the field equals scmd->eh_timeout which is used for normal command timeout. As this can be confusing, renaming scmd->eh_timeout to something like scmd->cmd_timeout would be good.
Reworked such that timeout race window is kept at minimal level as pointed out by James Bottomley.
02_scsi_timer_eh_timer_remove_spurious_if.patch : remove spurious if tests from scsi_eh_{times_out|done}
If tests which check if eh_action isn't NULL in both functions are always true. Remove the if's.
03_scsi_timer_dispatch_race_fix.patch : remove a timer race in scsi_queue_insert()
scsi_queue_insert() has four callers. Three callers call with timer disabled and one (the second invocation in scsi_dispatch_cmd()) calls with timer activated. scsi_queue_insert() used to always call scsi_delete_timer() and ignore the return value. This results in race with timer expiration. Remove scsi_delete_timer() call from scsi_queue_insert() and make the caller delete timer and check the return value.
04_scsi_timer_remove_delete_timer_from_reset_provider.patch : remove unnecessary scsi_delete_timer() call in scsi_reset_provider()
scsi_reset_provider() calls scsi_delete_timer() on exit which isn't necessary. Remove it.
[ End of patch descriptions ]
Thanks.
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