From patchwork Tue Mar 19 18:02:47 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emil Kronborg X-Patchwork-Id: 13596988 Received: from mail-4316.protonmail.ch (mail-4316.protonmail.ch [185.70.43.16]) (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 39E752C19D for ; Tue, 19 Mar 2024 18:03:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.70.43.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710871383; cv=none; b=khSj3nm9ysYt8PmyUs+F0eWj/ln+BqEb642NAOEWyICRsiQBW8oLYVz9syIJ9ecqEH3ikcqZk008dwNmMzyfg4cSohhLcrHUE31Uc46EbK+udGIiXjJ2TxMbegD1MyFdDCqBtm7ctGKLynLBRSLkooGb0acfSFZRRpzvbbqabvk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710871383; c=relaxed/simple; bh=/bOYxA0veCdTw7dWZj2qwekiYpyvVOARZ2+vTVGh08w=; h=Date:To:From:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=WfOP4U/HlDDutEsZQXTAOcf5n0Y8i1XAqZ2Eofrwyio1Ub7B50YhGoaOofTphI7W0/f+jmaDcTF4wTLv6tqIrXmNgyEEgpZFV4eXrwyomoQAwU35nR8OP2X8o3EC+vYlOA0xRoheTqFytFNBY/VO2upGkR4HnnMNleYkY30mtOo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=protonmail.com; spf=pass smtp.mailfrom=protonmail.com; dkim=pass (2048-bit key) header.d=protonmail.com header.i=@protonmail.com header.b=NPRXUTTh; arc=none smtp.client-ip=185.70.43.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=protonmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=protonmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=protonmail.com header.i=@protonmail.com header.b="NPRXUTTh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1710871373; x=1711130573; bh=AA4YbM0umuAl4kGtml9n7UI9KGtZnTLfV5Axe2bZA3o=; h=Date:To:From:Cc:Subject:Message-ID:Feedback-ID:From:To:Cc:Date: Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=NPRXUTThmrkX0+ybosBhdcwELKM7EDYZ1SURCv6t1gUFPUdp4yRh0BKPtZkelos1h VJyfQboos07nSBKJAQi2CC77UPYPMQ7KHYpWLtpcRA5aVi50yxNkLI1yKvRAKteEng pLa9qvEa9eTfp1+PdhAhY68QH4eHkZ2ndrWVHWXxDIpvUOwZ+thr6oRP0NDGCtUygz meIjrX2AnRfNsa6aizGo4Gh7vdjB/JDx7J8Qa9H5baaJmW8KhXtzIHKNIjk63ovKpf K2MBEFY5CoFFTZqUTUylA8O0ovgUUwwc7R1/ZSyjrhUWpg3ez8f2tKm/Kplu4vmy2U WJXva94zvDztA== Date: Tue, 19 Mar 2024 18:02:47 +0000 To: jirislaby@kernel.org, gregkh@linuxfoundation.org From: Emil Kronborg Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, Emil Kronborg , stable@vger.kernel.org Subject: [PATCH v2] serial: mxs-auart: add spinlock around changing cts state Message-ID: <20240319180239.69765-1-emil.kronborg@protonmail.com> Feedback-ID: 20949900:user:proton Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The uart_handle_cts_change() function in serial_core expects the caller to hold uport->lock. For example, I have seen the below kernel splat, when the Bluetooth driver is loaded on an i.MX28 board. [ 85.119255] ------------[ cut here ]------------ [ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec [ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs [ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1 [ 85.151396] Hardware name: Freescale MXS (Device Tree) [ 85.156679] Workqueue: hci0 hci_power_on [bluetooth] (...) [ 85.191765] uart_handle_cts_change from mxs_auart_irq_handle+0x380/0x3f4 [ 85.198787] mxs_auart_irq_handle from __handle_irq_event_percpu+0x88/0x210 (...) Cc: stable@vger.kernel.org # v6.1+ Fixes: 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers") Signed-off-by: Emil Kronborg Reviewed-by: Frank Li --- Changes in v2: - Add more of the stack trace to show why the lock is necessary. Note that i removed some unrelated noise for unwinding, showing and dumping the stack trace. - Add Fixes tag. Note that this commit do not fix 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers") as such, but it was the closest commit I could find that makes sense. - Cc stable. Commit b0af4bcb4946 ("serial: core: Provide port lock wrappers") is a prerequisite. Therefore, v6.1+. drivers/tty/serial/mxs-auart.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 4749331fe618..1e8853eae504 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -1086,11 +1086,13 @@ static void mxs_auart_set_ldisc(struct uart_port *port, static irqreturn_t mxs_auart_irq_handle(int irq, void *context) { - u32 istat; + u32 istat, stat; struct mxs_auart_port *s = context; u32 mctrl_temp = s->mctrl_prev; - u32 stat = mxs_read(s, REG_STAT); + uart_port_lock(&s->port); + + stat = mxs_read(s, REG_STAT); istat = mxs_read(s, REG_INTR); /* ack irq */ @@ -1126,6 +1128,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context) istat &= ~AUART_INTR_TXIS; } + uart_port_unlock(&s->port); + return IRQ_HANDLED; }