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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