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([2001:a61:1376:df01:e943:d12:a8fb:e1d7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4376686130csm13427380f8f.1.2026.02.09.02.03.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Feb 2026 02:03:17 -0800 (PST) Message-ID: <8e1c7ac5-e076-44b0-84b8-1b34b20f0ae1@suse.com> Date: Mon, 9 Feb 2026 11:03:09 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [usb?] INFO: task hung in usb_bulk_msg (2) To: Alan Stern , syzbot Cc: greearb@candelatech.com, hdanton@sina.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, michal.pecio@gmail.com, oneukum@suse.com, syzkaller-bugs@googlegroups.com References: <698905be.050a0220.3b3015.0061.GAE@google.com> <0b508f72-7248-479c-ad26-b9385e52c094@rowland.harvard.edu> Content-Language: en-US From: Oliver Neukum In-Reply-To: <0b508f72-7248-479c-ad26-b9385e52c094@rowland.harvard.edu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 09.02.26 02:26, Alan Stern wrote: > + expire = (timeout > 0) ? msecs_to_jiffies(timeout) : > + MAX_SCHEDULE_TIMEOUT; > + if (expire <= msecs_to_jiffies(MAX_UNINTERRUPTIBLE_TIMEOUT_MS)) > + rc = (wait_for_completion_timeout(&ctx.done, expire) > 0); > + else > + rc = (wait_for_completion_interruptible_timeout( > + &ctx.done, expire) > 0); > + if (!rc) { > usb_kill_urb(urb); > retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status); Hi, is this a proof of concept or a test of the real fix? I am afraid this is highly problematic. 1. You'll hit every user of the API. These are probably not ready to handle signals. This includes usb_bulk_message() and the interrupt version. 2. wait_for_completion_interruptible_timeout() reacts to _any_ signal. Do you really want to abort for SIGIO or SIGWINCH right after urb submission? 3. The error handling is broken. You cannot tell a true timeout and a signal apart. It seems to me that really want a clean API introducing usb_X_message_killable() Regards Oliver