Hello, James, Jens and Christoph.
This patchset removes misuses of scmd->eh_timeout and unexports SCSI
timer interface such that no one can misuse it anymore. #02 assumes
that the preceding scsi_send_eh_cmnd() patch is applied. Tested and
worked for me.
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_update_aic7xxx.patch
: make aic7xxx use its own timer instead of scmd->eh_timeout
aic7xxx used scmd->eh_timeout in its dv routines. This kind
of usage requires knowledge of and creates dependency into the
SCSI midlayer unnecessarily. This patch makes aic7xxx driver
use its own timer instead of scmd->eh_timeout.
Suggested by Christoph Hellwig.
02_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.
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.
05_scsi_timer_unexport_timer_functions.patch
: unexport scsi_{add|delete}_timer()
SCSI cmd timer has specific synchronization/semantic
requirements and shouldn't be directly used outside SCSI
midlayer. With aic7xxx driver updated, there's no user left.
This patch unexports scsi_{add|delete}_timer() routines and
also removes @complete argument from scsi_add_timer(). The
change makes the use of scsi_times_out() confined in
scsi_error.c, so move it upward such that no prototype is
needed and make it static.
06_scsi_timer_update_api_doc.patch
: Delete scsi_{add|delete}_timer() from scsi_mid_low_api.txt
As scsi_{add|delete}_timer() got unexported, remove them from
the API doc.
07_scsi_timer_strict_reuse.patch
: make reuse of SCSI cmd timer strict
SCSI cmd timer shouldn't be reused while it's active. Make
sure that the unused condition is marked with
eh_timeout->function = NULL and BUG() active reuse path.
[ End of patch descriptions ]
Thanks a lot.
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