From mboxrd@z Thu Jan 1 00:00:00 1970 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 12498C4167D for ; Tue, 14 Nov 2023 18:04:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233815AbjKNSE6 (ORCPT ); Tue, 14 Nov 2023 13:04:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233804AbjKNSEr (ORCPT ); Tue, 14 Nov 2023 13:04:47 -0500 Received: from mail-lf1-f46.google.com (mail-lf1-f46.google.com [209.85.167.46]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D80A6181; Tue, 14 Nov 2023 10:04:34 -0800 (PST) Received: by mail-lf1-f46.google.com with SMTP id 2adb3069b0e04-50a6ff9881fso7229999e87.1; Tue, 14 Nov 2023 10:04:34 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699985073; x=1700589873; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Ey9erX/YrVlUPvW8qimZgQRTCPhSsciFIT0777za9CM=; b=DZJVbwJNSedgo/bS2hR5rxADTM8P3WjdP5xE8U6At8q3KkDMnCbNUAU3Ud5Gu+yZsi qYV8g2wMNi4qK16SkI1xg2YKE07/T+vikLN098dn8prWL66iF1u5Niai/cVR0PKXa4pr gjlucFgL7T3b5r6ag9pGd2jc2gLIyVphOro6jXRHebWw4tmjTbl8cL3ufcD8DkR8uoAa Ze//4OW6a3Lp/AJLvGayNO+Evq/dsteCFl0N5485D/VS5+VtvWq7KSWRZBYnZOehfLTd XR5HxaDd/QS5ATBK8J11SpsXmKtJOz7ff7a/PirX2VfAz+brFggXWSYjdHq9/MmI7WLZ e0UQ== X-Gm-Message-State: AOJu0YyEKgjUUH1zXh/j17IpamBBPfZKuW8uGG7W9TpU2nsYf1upXQnN T5FI4bBJuEJ29pnwuWJvVG5FLo/BLx4= X-Google-Smtp-Source: AGHT+IFYwfGAP1QXLzYS/irG8xw6JaTeR+eUlbQEDk65Usr2OGHi+c8qJNznffpy88lJr/IBOr6USQ== X-Received: by 2002:a05:6512:3f0:b0:50a:6fc5:e95c with SMTP id n16-20020a05651203f000b0050a6fc5e95cmr6134583lfq.60.1699985072699; Tue, 14 Nov 2023 10:04:32 -0800 (PST) Received: from ?IPV6:2a0b:e7c0:0:107::bbbb:121? ([2a0b:e7c0:0:107::bbbb:121]) by smtp.gmail.com with ESMTPSA id a67-20020a509ec9000000b0053e43492ef1sm5467491edf.65.2023.11.14.10.04.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Nov 2023 10:04:32 -0800 (PST) Message-ID: <5da1d0d3-9677-4c9a-8568-d24db389465c@kernel.org> Date: Tue, 14 Nov 2023 19:04:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6] /proc/sysrq-trigger: accept multiple keys at once Content-Language: en-US To: Tomas Mudrunka Cc: corbet@lwn.net, gregkh@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org References: <20231114124152.97010-1-tomas.mudrunka@gmail.com> <20231114151252.117575-1-tomas.mudrunka@gmail.com> From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20231114151252.117575-1-tomas.mudrunka@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 14. 11. 23, 16:12, Tomas Mudrunka wrote: > Just for convenience. > This way we can do: > `echo _reisub > /proc/sysrq-trigger` > Instead of: > `for i in r e i s u b; do echo "$i" > /proc/sysrq-trigger; done;` > > This can be very useful when trying to execute sysrq combo remotely > or from userspace. When sending keys in multiple separate writes, > userspace can be killed before whole combo is completed. > Therefore putting all keys in single write is more robust approach. > > Signed-off-by: Tomas Mudrunka > --- > V5 -> V6: Documentation now has notice about undefined behavior > V4 -> V5: Added this list of changes > V3 -> V4: Bulk is now bool instead of char (and fixed typo) > V2 -> V3: Fixed code styling (and introduced typo) > V1 -> V2: Bulk mode only activated by underscore now, added docs > > Documentation/admin-guide/sysrq.rst | 11 ++++++++++- > drivers/tty/sysrq.c | 17 ++++++++++++++--- > 2 files changed, 24 insertions(+), 4 deletions(-) > > diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst > index 51906e473..e7a82cba7 100644 > --- a/Documentation/admin-guide/sysrq.rst > +++ b/Documentation/admin-guide/sysrq.rst > @@ -75,10 +75,19 @@ On other > submit a patch to be included in this section. > > On all > - Write a character to /proc/sysrq-trigger. e.g.:: > + Write single character to /proc/sysrq-trigger. a single > + Only first character is interpreted, rest of string is ignored. the first; the rest of the string > + However it is not reccomended to write any extra characters However, <- comma recommended > + as the behavior is undefined and might change in the future versions. > + e.g.:: Even the original was lowercase. But it should be "E.g.::", right -- Greg/Jon? > > echo t > /proc/sysrq-trigger > > + Alternatively write multiple keys combo prepended by underscore. Alternatively, <- comma s/keys/characters/ an underscore > + All characters are interpreted this way. e.g.:: This way, all characters are interpreted. (IMO this has a different meaning, but natives would have to tell us.) > + > + echo _reisub > /proc/sysrq-trigger > + > The :kbd:`` is case sensitive. > > What are the 'command' keys? > diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c > index 6b4a28bcf..ad07bc812 100644 > --- a/drivers/tty/sysrq.c > +++ b/drivers/tty/sysrq.c > @@ -1150,16 +1150,27 @@ EXPORT_SYMBOL(unregister_sysrq_key); > #ifdef CONFIG_PROC_FS > /* > * writing 'C' to /proc/sysrq-trigger is like sysrq-C > + * If first character in write is underscore, all characters are interpreted. If the first character written is thanks, -- js suse labs