From patchwork Wed Dec 8 22:56:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Khazhismel Kumykov X-Patchwork-Id: 522426 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B4E6C433FE for ; Wed, 8 Dec 2021 22:57:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240871AbhLHXAq (ORCPT ); Wed, 8 Dec 2021 18:00:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240862AbhLHXAp (ORCPT ); Wed, 8 Dec 2021 18:00:45 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16FE2C0617A2 for ; Wed, 8 Dec 2021 14:57:13 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id t1-20020a5b03c1000000b005f6ee3e97easo6885202ybp.16 for ; Wed, 08 Dec 2021 14:57:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=nCfxssMPsD1q0PyBbkNGtQFLjh9qoKfE83Oexh+AmmA=; b=YBx3RFczyrcSsixyAF7h7KOLkaoHrPZWobhhDnkGZnOHeqQ6N4k1n+eDUypoARW6XS pxFCSN7KMfB4y0z+nkNJC1Sw6sKPfrZlXmQDBYhp2uyDjiRz62ARepwRcOZ2lj3JbdUs lOhrILxaVoaJ3uKiB1jHMD80dciECooXdDtlAapvBze31ztONDK7y0jFlWUB7eVuKtq5 MEE6IdKwYhSit6NQC/M9W3sgmnMt9r34YwCtXwPgzNulKJWmXxXxHhrLH7jjt3OXVizp J2g/mDnypmNG5cezxnaw9YSQxVwqorYiWVeC7ACovkrC6hggHrW5e2sp7gkFp2IseH5n 2m4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=nCfxssMPsD1q0PyBbkNGtQFLjh9qoKfE83Oexh+AmmA=; b=FNS9yuqCIDAaGJglbfwCetMNrZ6M0rW3SgVGOpdIUCtCwmpO5HT+LgeqqvLfdIKR/j dxB8x/SQnhB6si6KG0Un8akwcjV/pynKc7LGgms6AubSYe7HzG3V56Mc66ohnQoba6yB 6906yNU8w6BfnldwNX1Z1fmCKoqH/Iz/Cd+Pl55++YEVuCYzWm88mi2A3hwEosr86ogo bRYwMc8JjgyiOfieYErvkPYRG4XIcWQMlzajSGxuqor8lzcJHGs5AGuwDKeCgjkSGxeo GBED5vwFI+c6FnEHp7zFmAKbL9bYwR2wCAK09lKGcN1cuFwZlCOiTZdVVX9aQd8rd/zw QFKw== X-Gm-Message-State: AOAM53332hXmGJD2WmhbHS4FpZP9KLniKCzSTNQbzEqY53yQ8qAB1/Ka uNrelXlLNxCYx4T0BPw1p+/6DfJVzQQ= X-Google-Smtp-Source: ABdhPJwhWwgj5Q80ol/VS55EsbWI8O4643ncWp8nGwhdNJDuYwgHDsQcQforxY1tB0qDeeSnSsbP39mGtc0= X-Received: from khazhy-linux.svl.corp.google.com ([2620:15c:2cd:202:5e01:df39:4a79:a13]) (user=khazhy job=sendgmr) by 2002:a25:e090:: with SMTP id x138mr1877571ybg.501.1639004232010; Wed, 08 Dec 2021 14:57:12 -0800 (PST) Date: Wed, 8 Dec 2021 14:56:37 -0800 Message-Id: <20211208225637.1054164-1-khazhy@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.34.1.400.ga245620fadb-goog Subject: [PATCH] scsi: docs: update notes about scsi_times_out From: Khazhismel Kumykov To: Jonathan Corbet , "James E.J. Bottomley" , "Martin K. Petersen" Cc: linux-doc@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, bvanassche@acm.org, Hannes Reinecke , Khazhismel Kumykov Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org 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 --- 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.