lkml.org 
[lkml]   [2021]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH] scsi: docs: update notes about scsi_times_out
From
eh_timed_out() is not limited by scmd->allowed, and can reset timer
forever, and retries happen in the abort handler.

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(-)

I'm by no means a scsi expert, but this section didn't seem to line up
with the code that's actually written. Aiming to at least save the
confusion for the next person :) As written, it seems like scsi drivers
implementing eh_timed_out can only issue RESET_TIMER a finite number of
times, but e.g. virtio_scsi relies on being able to reset indefinitely.

(thanks bart for the pointer to where the RESET_TIMER change happened!)


diff --git a/Documentation/scsi/scsi_eh.rst b/Documentation/scsi/scsi_eh.rst
index 7d78c2475615..4c56a33a716f 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 asynchrous abort. which may
+ issue a retry scmd->allowed + 1 times. 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), when retries are exceeded, or when the EH deadline is expired. In
+ these case 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.
--
2.34.1.400.ga245620fadb-goog
\
 
 \ /
  Last update: 2021-12-08 23:58    [W:0.088 / U:0.492 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site