From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794064309; b=DvoKBwRJ99McFK4zY1borTSeIQheTE379oo4nelIYKjlriwtSN2X0rGifa8t+rXkAa0w pJw8itcEuKYPa7z+tQTS3UlZCtADpvGhsxmLmzQAGyPa5zLv1sYTFjmcDmgKebd71p+WY J9lododUsMwLwcCqOcn6RWhFaqcyc7aNo0tu9IF8U9ZBxFbcXSPslLmyjWO/hsIcbzowX THVBkyq4m0NM9HEltsk+pmbuwIVgbRuvc/eyqPdH+T4rXdaPWC+PKrmBWb0EI0dp+eu/t 7BT5UdPM9vqe39UaV5ShJ8nxBjmggZW7yVTsVR065kmADwJDHelte/PSgnGLSQPeHaw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794064309; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=4cxzjGvejxDxZaM4Hs69LerBX51PSjjvPLwL/ApoxyQ=; b=Dk9rMIr4Odi6+i73MYpJJdkmKQKMmqQfoe2G/p4/egdjErdWInzmBraYEF81UaJAk/Kf lpUipxGW84XK6J3Ik9ydUWR5TkqGwQ5Svsw7HjDaVRbaAwdltwpDFgmtXz8Mz8JwZ936i yFx7LbiNHixo5p8uYeA0bjFtu4Lss4VzrXm+dfmqaTmMZTVnxhMODCsEVj0YyV9H3GnxQ uZhW7oWrCrzFGkDwMa5XeKkVICZv4lFCJB2ZdQUdUoTJRdQq7z1SPXUqRHLrl2RYZpJZD 4eGvFRJ0L0DCy/i3x2Le0WjjUYaTylQMrmZYclZZqdneIpPbQ5LyFnGpltVYPqSIrfg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=I1Icxybp; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75291606C030; Sat, 7 Nov 2026 15:11:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=I1Icxybp Received: by smtp.kernel.org (Postfix) with ESMTPSA id 209841F0089F; Sat, 7 Nov 2026 15:11:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794064309; bh=4cxzjGvejxDxZaM4Hs69LerBX51PSjjvPLwL/ApoxyQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=I1IcxybpyxaqYOHTQMnd9cmVq+ojYlUVu8D/q3zqk71J/mBWRR3vF3EF7qbFZ3NTN zGitxRTG2SgOxXmUyHzBbBIUPN626SpXkCRhlz3k2t/Nt7N8uB6dLiC6Ecco/Ck98P KtD4fFQx+hLTYydJ4zMwtNZ6M0ayjRRLfuVXhcVQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Johan Hovold , Sasha Levin , stable@kernel.org Subject: [PATCH 7.3 0400/1257] staging: greybus: uart: fix racy TIOCMIWAIT implementation Date: Sat, 7 Nov 2026 08:44:56 -0500 Message-ID: <20261107134950.583527540@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134939.434104957@linuxfoundation.org> References: <20261107134939.434104957@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold [ Upstream commit e94cda6551d4716b17353fc458baa9e85ddea9ff ] Check the wakeup condition after adding the task to the waitqueue and updating the task state to avoid missing a racing modem status update or disconnect. Store the old icount on entry and do not update it in the completion handler to avoid missing events or reporting spurious ones (due to modem status changes before TIOCMIWAIT was called). Fixes: e68453ed28c5 ("greybus: uart-gb: now builds, more framework added") Cc: stable@kernel.org # 4.9 Cc: Greg Kroah-Hartman Signed-off-by: Johan Hovold Link: https://patch.msgid.link/20260907095305.130762-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/staging/greybus/uart.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c index 172cf900eaf0b..2c47418a11ef8 100644 --- a/drivers/staging/greybus/uart.c +++ b/drivers/staging/greybus/uart.c @@ -53,7 +53,6 @@ struct gb_tty { spinlock_t read_lock; spinlock_t write_lock; struct async_icount iocount; - struct async_icount oldcount; wait_queue_head_t wioctl; struct mutex mutex; u8 ctrlin; /* input control lines */ @@ -643,11 +642,16 @@ static int wait_serial_change(struct gb_tty *gb_tty, unsigned long arg) if (!(arg & (TIOCM_DSR | TIOCM_RI | TIOCM_CD))) return -EINVAL; - do { + spin_lock_irq(&gb_tty->read_lock); + old = gb_tty->iocount; + spin_unlock_irq(&gb_tty->read_lock); + + add_wait_queue(&gb_tty->wioctl, &wait); + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + spin_lock_irq(&gb_tty->read_lock); - old = gb_tty->oldcount; new = gb_tty->iocount; - gb_tty->oldcount = new; spin_unlock_irq(&gb_tty->read_lock); if ((arg & TIOCM_DSR) && (old.dsr != new.dsr)) @@ -657,18 +661,20 @@ static int wait_serial_change(struct gb_tty *gb_tty, unsigned long arg) if ((arg & TIOCM_RI) && (old.rng != new.rng)) break; - add_wait_queue(&gb_tty->wioctl, &wait); - set_current_state(TASK_INTERRUPTIBLE); - schedule(); - remove_wait_queue(&gb_tty->wioctl, &wait); if (gb_tty->disconnected) { - if (arg & TIOCM_CD) - break; retval = -ENODEV; - } else if (signal_pending(current)) { + break; + } + + schedule(); + + if (signal_pending(current)) { retval = -ERESTARTSYS; + break; } - } while (!retval); + } + __set_current_state(TASK_RUNNING); + remove_wait_queue(&gb_tty->wioctl, &wait); return retval; } -- 2.53.0