From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BF9D111C86 for ; Thu, 24 Aug 2023 14:53:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41196C433C7; Thu, 24 Aug 2023 14:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692888810; bh=hk7DY3fYO7HyvsFp7Nhn0t3HcnF407ukLKHFS1ScQGg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fI7wSwjFso+qjcduMeqhLGJoMRrZuIKTYqGEogE9ttbvghZlwr2RJsjC+uBdXRY0V zaKVMGwMyiFMW0CWqVOjjEBnjSa+X9ikKF6wgr22TkNO5HMb6VujOloYDOoM4H9YLa 0Gbe2sspy1P237AttkMppZStsiQ5kDOINBfV9hiU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Prashanth K , Sasha Levin Subject: [PATCH 5.15 021/139] usb: gadget: u_serial: Avoid spinlock recursion in __gs_console_push Date: Thu, 24 Aug 2023 16:49:04 +0200 Message-ID: <20230824145024.488424147@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230824145023.559380953@linuxfoundation.org> References: <20230824145023.559380953@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Prashanth K [ Upstream commit e5990469943c711cb00bfde6338d2add6c6d0bfe ] When serial console over USB is enabled, gs_console_connect queues gs_console_work, where it acquires the spinlock and queues the usb request, and this request goes to gadget layer. Now consider a situation where gadget layer prints something to dmesg, this will eventually call gs_console_write() which requires cons->lock. And this causes spinlock recursion. Avoid this by excluding usb_ep_queue from the spinlock. spin_lock_irqsave //needs cons->lock gs_console_write . . _printk __warn_printk dev_warn/pr_err . . [USB Gadget Layer] . . usb_ep_queue gs_console_work __gs_console_push // acquires cons->lock process_one_work Signed-off-by: Prashanth K Link: https://lore.kernel.org/r/1683638872-6885-1-git-send-email-quic_prashk@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_serial.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index a8d1e8b192c55..f975dc03a1904 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -915,8 +915,11 @@ static void __gs_console_push(struct gs_console *cons) } req->length = size; + + spin_unlock_irq(&cons->lock); if (usb_ep_queue(ep, req, GFP_ATOMIC)) req->length = 0; + spin_lock_irq(&cons->lock); } static void gs_console_work(struct work_struct *work) -- 2.40.1