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Date:   Fri, 18 Feb 2022 16:16:01 -0800
Message-Id: <20220219001601.3534043-1-khazhy@google.com>
Mime-Version: 1.0
Subject: [PATCH v2] scsi: docs: update notes about scsi_times_out
From:   Khazhismel Kumykov <khazhy@google.com>
To:     Jonathan Corbet <corbet@lwn.net>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
Cc:     linux-doc@vger.kernel.org, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, bvanassche@acm.org,
        Hannes Reinecke <hare@suse.com>,
        Khazhismel Kumykov <khazhy@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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")

Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
---
 Documentation/scsi/scsi_eh.rst | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/Documentation/scsi/scsi_eh.rst b/Documentation/scsi/scsi_eh.rst
index 7d78c2475615..885395dc1f15 100644
--- 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.
-- 
2.35.1.473.g83b2b277ed-goog