From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 72BDE749A for ; Thu, 12 Jan 2023 14:04:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9F66C433F1; Thu, 12 Jan 2023 14:04:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673532259; bh=hWLTob0lBU1E/N9Lb1t/BDJoVddh6CY495jSnOwh1rI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RhobhyPQ59/ggNmy5892A2SJTxgW/UjZwKHn2upyQ6/QsFWw/1HdSyIUG2hqt9Nw1 +k3Bch13iApAcMzMhGEurchJL1ubl0u4vGb39gAtA+xE7lvHaMQVJaXB/xpQ3d9ukt QGC58/p8rA9rN+4TptcQQ/lb4XgNeUd6Xvo05UF8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wolfram Sang , Jonathan Corbet , Sasha Levin Subject: [PATCH 5.10 073/783] docs: fault-injection: fix non-working usage of negative values Date: Thu, 12 Jan 2023 14:46:29 +0100 Message-Id: <20230112135527.538017220@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230112135524.143670746@linuxfoundation.org> References: <20230112135524.143670746@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Wolfram Sang [ Upstream commit 005747526d4f3c2ec995891e95cb7625161022f9 ] Fault injection uses debugfs in a way that the provided values via sysfs are interpreted as u64. Providing negative numbers results in an error: /sys/kernel/debug/fail_function# echo -1 > times sh: write error: Invalid argument Update the docs and examples to use "printf %#x " in these cases. For "retval", reword the paragraph a little and fix a typo. Signed-off-by: Wolfram Sang Link: https://lore.kernel.org/r/20210603125841.27436-1-wsa+renesas@sang-engineering.com Signed-off-by: Jonathan Corbet Stable-dep-of: d472cf797c4e ("debugfs: fix error when writing negative value to atomic_t debugfs file") Signed-off-by: Sasha Levin --- .../fault-injection/fault-injection.rst | 24 +++++++++++-------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst index 31ecfe44e5b4..f47d05ed0d94 100644 --- a/Documentation/fault-injection/fault-injection.rst +++ b/Documentation/fault-injection/fault-injection.rst @@ -78,8 +78,10 @@ configuration of fault-injection capabilities. - /sys/kernel/debug/fail*/times: - specifies how many times failures may happen at most. - A value of -1 means "no limit". + specifies how many times failures may happen at most. A value of -1 + means "no limit". Note, though, that this file only accepts unsigned + values. So, if you want to specify -1, you better use 'printf' instead + of 'echo', e.g.: $ printf %#x -1 > times - /sys/kernel/debug/fail*/space: @@ -167,11 +169,13 @@ configuration of fault-injection capabilities. - ERRNO: retval must be -1 to -MAX_ERRNO (-4096). - ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096). -- /sys/kernel/debug/fail_function//retval: +- /sys/kernel/debug/fail_function//retval: - specifies the "error" return value to inject to the given - function for given function. This will be created when - user specifies new injection entry. + specifies the "error" return value to inject to the given function. + This will be created when the user specifies a new injection entry. + Note that this file only accepts unsigned values. So, if you want to + use a negative errno, you better use 'printf' instead of 'echo', e.g.: + $ printf %#x -12 > retval Boot option ^^^^^^^^^^^ @@ -255,7 +259,7 @@ Application Examples echo Y > /sys/kernel/debug/$FAILTYPE/task-filter echo 10 > /sys/kernel/debug/$FAILTYPE/probability echo 100 > /sys/kernel/debug/$FAILTYPE/interval - echo -1 > /sys/kernel/debug/$FAILTYPE/times + printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times echo 0 > /sys/kernel/debug/$FAILTYPE/space echo 2 > /sys/kernel/debug/$FAILTYPE/verbose echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait @@ -309,7 +313,7 @@ Application Examples echo N > /sys/kernel/debug/$FAILTYPE/task-filter echo 10 > /sys/kernel/debug/$FAILTYPE/probability echo 100 > /sys/kernel/debug/$FAILTYPE/interval - echo -1 > /sys/kernel/debug/$FAILTYPE/times + printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times echo 0 > /sys/kernel/debug/$FAILTYPE/space echo 2 > /sys/kernel/debug/$FAILTYPE/verbose echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait @@ -336,11 +340,11 @@ Application Examples FAILTYPE=fail_function FAILFUNC=open_ctree echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject - echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval + printf %#x -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval echo N > /sys/kernel/debug/$FAILTYPE/task-filter echo 100 > /sys/kernel/debug/$FAILTYPE/probability echo 0 > /sys/kernel/debug/$FAILTYPE/interval - echo -1 > /sys/kernel/debug/$FAILTYPE/times + printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times echo 0 > /sys/kernel/debug/$FAILTYPE/space echo 1 > /sys/kernel/debug/$FAILTYPE/verbose -- 2.35.1