scsi: core: docs: Update notes about scsi_times_out

Most importantly: eh_timed_out() is not limited by scmd->allowed, and can
reset timer forever.

Fixes: c829c394165f ("[SCSI] FC transport : Avoid device offline cases by stalling aborts until device unblocked")
Link: https://lore.kernel.org/r/20220219001601.3534043-1-khazhy@google.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/Documentation/scsi/scsi_eh.rst b/Documentation/scsi/scsi_eh.rst
index 7d78c24756155b1405f0109b73a8293aa674a8ba..885395dc1f15231b0368a0532b9dc99bc266a787 100644 (file)
--- a/Documentation/scsi/scsi_eh.rst
+++ b/Documentation/scsi/scsi_eh.rst
@@ -95,19 +95,18 @@ function
 
     - BLK_EH_RESET_TIMER
        This indicates that more time is required to finish the
-       command.  Timer is restarted.  This action is counted as a
-       retry and only allowed scmd->allowed + 1(!) times.  Once the
-       limit is reached, action for BLK_EH_DONE is taken instead.
+       command.  Timer is restarted.
 
     - BLK_EH_DONE
         eh_timed_out() callback did not handle the command.
        Step #2 is taken.
 
- 2. scsi_abort_command() is invoked to schedule an asynchrous abort.
-    Asynchronous abort are not invoked for commands which the
-    SCSI_EH_ABORT_SCHEDULED flag is set (this indicates that the command
-    already had been aborted once, and this is a retry which failed),
-    or when the EH deadline is expired. In these case Step #3 is taken.
+ 2. scsi_abort_command() is invoked to schedule an asynchronous abort which may
+    issue a retry scmd->allowed + 1 times.  Asynchronous aborts are not invoked
+    for commands for which the SCSI_EH_ABORT_SCHEDULED flag is set (this
+    indicates that the command already had been aborted once, and this is a
+    retry which failed), when retries are exceeded, or when the EH deadline is
+    expired. In these cases Step #3 is taken.
 
  3. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
     command.  See [1-4] for more information.