From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 07F7D406834; Mon, 7 Sep 2026 06:56:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764204; cv=none; b=aJpU+wbrc3TDcfXnUYsD51+V6EiwQMaY746RCKYY9rKIwogqe0kZXkFgA5FUmcoEyHSsEbIugMgtphtEzWhO2nIzFHTFQX/pLDkBD/LujzpxYd+RKcZF25seqnPN+AZytMlChrRv+7CMN4houIvmYBDq4n90JGO7nPXS9NjBvoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764204; c=relaxed/simple; bh=/wkMVvADfANsF88IfEhps+ta/Rq2LjzqGVcIwAnw4VI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hqXZSsoCNpGVUUtFgaGGAw7fMP2xTzz6I51XJcxVZOHczF1WlFJJ3uJbxePcISA8mlz9OPoCrE0j/Sv1Zs1/1N92Kkv56iI1vVzSBRQXAb/tSLLFUJ7ZEIECtoJ51tQuQQhVukwieKht+KqjIS2d/QMsvXaoy5vrDKfAPRU28Lg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ct1QvAzZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ct1QvAzZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C0F81F00A3A; Mon, 7 Sep 2026 06:56:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788764202; bh=/m4zDVNEv3Vemxw3xr7Ub1WP3qAIAIAjBDAXA7mngxA=; h=From:To:Cc:Subject:Date; b=ct1QvAzZifzGIOuDnC+M19+trfyZXoAmEWMVygurMOj1/pmdGCQlZd1Yaikb2og/9 BH0ljSa2UkExdY3yx5ssx+mVygqIDy4ZoQedX3sF0fw676afJisdLII0ww/7yvsbFZ v/3vgDkvr/lsSCPgAn5juRrnDmZC0A/p3FXxVHAB6ZB0yoIwvyghGsJczu/MzdLMbL nhNi39ujCwoUYix05+xBXCJgC9ZAbcvmW+b3Og8uohhA7vBq632wsA22BF1grSm/qi nv11Fqlh7/zhvl0arCmkPgOysaG8TOdgGfQzNRzWdIJsYLcZ7WfdDUzozVf9SUQZUq Vok2X/Ehw0oqQ== Received: from johan by xi.lan with local (Exim 4.99.4) (envelope-from ) id 1x3THU-00000000QJd-1w8c; Mon, 07 Sep 2026 08:56:40 +0200 From: Johan Hovold To: David Lin , Johan Hovold , Alex Elder , Greg Kroah-Hartman Cc: greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] staging: greybus: uart: fix racy TIOCMIWAIT implementation Date: Mon, 7 Sep 2026 08:56:32 +0200 Message-ID: <20260907065632.101144-1-johan@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The wakeup condition needs to be checked after adding the task to the waitqueue and updating the task state to avoid missing a racing modem status update or disconnect. Fixes: e68453ed28c5 ("greybus: uart-gb: now builds, more framework added") Cc: stable@vger.kernel.org # 4.9 Cc: Greg Kroah-Hartman Signed-off-by: Johan Hovold --- drivers/staging/greybus/uart.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c index 24b4dab069c3..bcfea0a02155 100644 --- a/drivers/staging/greybus/uart.c +++ b/drivers/staging/greybus/uart.c @@ -643,7 +643,10 @@ static int wait_serial_change(struct gb_tty *gb_tty, unsigned long arg) if (!(arg & (TIOCM_DSR | TIOCM_RI | TIOCM_CD))) return -EINVAL; - do { + 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; @@ -657,18 +660,20 @@ 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; } -- 2.55.0