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Sun, 26 May 2024 14:57:15 +0200 Message-ID: <369912bd-2ccf-4cb7-817a-a32ccbb3d83d@web.de> Date: Sun, 26 May 2024 14:57:07 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Yu Kuai , linux-block@vger.kernel.org, kernel-janitors@vger.kernel.org, Bart Van Assche , Chaitanya Kulkarni , Chengming Zhou , Damien Le Moal , Hannes Reinecke , Jens Axboe , Johannes Thumshirn , Yi Zhang , Zhu Yanjun Cc: LKML , Yang Erkun , Yi Zhang , Yu Kuai References: <20240523153934.1937851-1-yukuai1@huaweicloud.com> Subject: Re: [PATCH v2] null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues' Content-Language: en-GB From: Markus Elfring In-Reply-To: <20240523153934.1937851-1-yukuai1@huaweicloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:FdTFfjKeMbueufJpEs7qeLt78+mhGzQxV8dbJ8BZleWz5WKA7rT FmGUKdTjZd2dbVMLZpVl7LIsbMuJLfg+tHDnPWxHvuhi4yjHMtb/37F+G0k0OMUZSklQxrR U7j1LjI7dnRcX0WfLVIBFx/4LC/ivVsTNZYd13CSXIxcr2ousa0Dmfbf7RWLbsBjyhD+AZc v55JqHyCA8lj+nijOSZUg== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:RONZyowvkdA=;qIEX4tPfOuBuJwMVujzM1AjwnE1 fXfbD52+wJJcpo3wOabKrMkSIDjnDwSl8GM15LMmisc19pOR3V1pMZesXaadRNs19u8Xj7375 ePbES4D9Y13fcIO69qSLHjB0GJOzqN1TjG3+fwRBflTPOHV3nDH95sWqVwau/8cJ16OCuMlnd JLcVWuVRbp3MH/xfZIly7mLV5lD8gulrxBpKEFZf79OHWlW4Tt0Gcdry76SWw9MQRLDcG0A3e JwEaAbBxy58YkZSiznpsrgVYiv66q5V0Ow35UxwhXLeIIVTAK1bGII4kWds/QUDkZpgkNILOk qA/HkQ8le1/9K056RAc5NuuDSrPfK7IUZkWFvCOPhZzJstTLDDsDr9LZP8vgNGZRglHCBsm3v MPrn8D4F35ovmZK5Vz9ZoP/BX4EOx95a6zsjCZVytgapfmRh6St6kTQr8gZuBKOjuEj1rbr3l VGBXNl3fUnB1UlMgEzgSjXkdDLUevJcAeFjelk2oyHUvKxh4PFLQ7OHiWlwIzQBpvg23n92SP iUljOEXZuzg744GjEZWWBu4h0sufg8aEQ9b80BwlA9h51WGarTeWFZr5LiQai5FFX3gv7ocB/ xVPeRvCZkvX8szP0Mh6KajMJxHkXuRF4en0E0V0ksrB+pBYbTc1lcwZqX6cbCndW/GgGyoVxh fhZWIYqzDqq7GlbKlxkxrQRrxuajaCtdgO+c0TsaAkZ5lwxQNJspvrvDocMxoWx1hI1Fe1eSg FLZeQNSEiGmu2i/N7RndvIWx8gLjsysEzPI3H6Fkw5QFsIVUUP1ZdGJQdQI1tdddeB0HINLIi +kkcErcdMI7Ry4PI9w7+koiRTUQ1nuSTln1TGTqLt8OPo= =E2=80=A6 > Fix this problem by resuing the global mutex to protect > nullb_device_power_store() and nullb_update_nr_hw_queues() from configfs= . > > Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after a= n instance has been configured") =E2=80=A6 > +++ b/drivers/block/null_blk/main.c > @@ -413,13 +413,25 @@ static int nullb_update_nr_hw_queues(struct nullb_= device *dev, > static int nullb_apply_submit_queues(struct nullb_device *dev, > unsigned int submit_queues) > { > - return nullb_update_nr_hw_queues(dev, submit_queues, dev->poll_queues)= ; > + int ret; > + > + mutex_lock(&lock); > + ret =3D nullb_update_nr_hw_queues(dev, submit_queues, dev->poll_queues= ); > + mutex_unlock(&lock); > + > + return ret; > } =E2=80=A6 How do you think about to increase the application of scope-based resource= management here? https://elixir.bootlin.com/linux/v6.9.1/source/include/linux/cleanup.h#L12= 4 Will development interests grow for the usage of a statement like =E2=80= =9Cguard(mutex)(&lock);=E2=80=9D? Regards, Markus