From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 D4D37168C3 for ; Tue, 14 Nov 2023 09:44:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BCDB191; Tue, 14 Nov 2023 01:44:19 -0800 (PST) Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-52bd9ddb741so8294666a12.0; Tue, 14 Nov 2023 01:44:19 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699955058; x=1700559858; 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=jUNzJ2edP92bJxD8AgDGlr8qj4Lt1Mw4NxCr0R4hJ8c=; b=PFZAdWoGiBU60YgLbOPTF80ovOjP63SajKy6iT8O4jOeqKXrHR0LGg+P4SWMzVUVJx sv8SulPwz9tYkLoJMuoIlYPiNlaPDEO1DlUU6LZKj3N/dLB9TsZ5wHscpgoJKPVVfzJy 8nSnK6ddI9NIUk0pCqACUgOlgS1IJkQjc8G4nwOkYvIw3xVGyH/rCK3UWHXk4plEaA4C +ttKTvYf+MTXOMU8aoF7FVk2rwvuTaBxKFieKobxcqoy0OpEpWmBp5jhfh4BomolwLbu XdwAkN0SebsbtM4cg2vqoGhtJjn5pUGDFW8jcO7M/4IXZhZHIkNuU+tuuWAuTB4/Eu/Q Rzuw== X-Gm-Message-State: AOJu0Yym3zHTAgQ9C+A8p+mYI8ipwUso+tvu42He/21Y96i7hfr9ut1h dvYF1ZphkH4piP2Yk/hJseE= X-Google-Smtp-Source: AGHT+IEQfONUWB4cDTMK0qP+dDw3hIEqdKbiG9dDjY4qhssIKf+Hxz+moOfEQRVmW2C98IIqhpsZQQ== X-Received: by 2002:a17:906:141b:b0:9e0:727a:e491 with SMTP id p27-20020a170906141b00b009e0727ae491mr6096699ejc.35.1699955057467; Tue, 14 Nov 2023 01:44:17 -0800 (PST) Received: from ?IPV6:2a0b:e7c0:0:107::aaaa:59? ([2a0b:e7c0:0:107::aaaa:59]) by smtp.gmail.com with ESMTPSA id z9-20020a170906714900b0099d804da2e9sm5285960ejj.225.2023.11.14.01.44.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Nov 2023 01:44:17 -0800 (PST) Message-ID: Date: Tue, 14 Nov 2023 10:44:16 +0100 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] /proc/sysrq-trigger: accept multiple keys at once Content-Language: en-US To: Tomas Mudrunka , gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, corbet@lwn.net, linux-doc@vger.kernel.org References: <2023111330-headstone-pyromania-c57e@gregkh> <20231114093525.71871-1-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: <20231114093525.71871-1-tomas.mudrunka@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14. 11. 23, 10:35, 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 > --- > Documentation/admin-guide/sysrq.rst | 4 ++++ > drivers/tty/sysrq.c | 17 ++++++++++++++--- > 2 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst > index 51906e473..9d46a33e5 100644 > --- a/Documentation/admin-guide/sysrq.rst > +++ b/Documentation/admin-guide/sysrq.rst > @@ -79,6 +79,10 @@ On all > > echo t > /proc/sysrq-trigger > > + Alternatively write key combo prepended by underscore. e.g.:: > + > + 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..3455e6dd3 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. > */ > static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, > size_t count, loff_t *ppos) > { > - if (count) { > + char bulk = false; bool > + size_t i; > + > + for (i = 0; i < count; i++) { > char c; > > - if (get_user(c, buf)) > + if (get_user(c, buf+i)) spaces around + > return -EFAULT; > - __handle_sysrq(c, false); > + > + if (c == '_') > + bulk = true; > + else > + __handle_sysrq(c, false); > + > + if (!bulk) > + break; > } > > return count; -- js suse labs