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([2402:f000:1:1501:200:5efe:a66f:473a]) by smtp.gmail.com with ESMTPSA id l85-v6sm7276214pfk.34.2018.09.05.19.35.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Sep 2018 19:35:18 -0700 (PDT) Subject: Re: [PATCH] hid: hid-core: Fix a sleep-in-atomic-context bug in __hid_request() To: Jiri Kosina Cc: benjamin.tissoires@redhat.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180901121659.1257-1-baijiaju1990@gmail.com> From: Jia-Ju Bai Message-ID: <6ec3d032-6d33-d2af-965f-7f3457dc8311@gmail.com> Date: Thu, 6 Sep 2018 10:35:14 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/9/5 16:29, Jiri Kosina wrote: > On Sat, 1 Sep 2018, Jia-Ju Bai wrote: > >> The driver may sleep with holding a spinlock. >> >> The function call paths (from bottom to top) in Linux-4.16 are: >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_core.c, 111: >> hid_hw_request in picolcd_send_and_wait >> drivers/hid/hid-picolcd_core.c, 100: >> _raw_spin_lock_irqsave in picolcd_send_and_wait >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_core.c, 245: >> hid_hw_request in picolcd_reset >> drivers/hid/hid-picolcd_core.c, 235: >> _raw_spin_lock_irqsave in picolcd_reset >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_fb.c, 215: >> hid_hw_request in picolcd_fb_reset >> drivers/hid/hid-picolcd_fb.c, 206: >> _raw_spin_lock_irqsave in picolcd_fb_reset >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-lg4ff.c, 465: >> hid_hw_request in lg4ff_play >> drivers/hid/hid-lg4ff.c, 441: >> _raw_spin_lock_irqsave in lg4ff_play >> >> To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC. >> >> This bug is found by my static analysis tool DSAC. > Could you please rewrite the changelog so that it's human readable? The > above is a bit hard to understand, I think something along the lines of > "__hid_request() has to be allocating with GFP_ATOMIC because there are > the following callchains leading to __hid_request() being an atomic > context: ... a->b->c.._hid_request()" etc. > Okay, I will send a new patch. Best wishes, Jia-Ju Bai