From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42974 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932654AbbJRClC (ORCPT ); Sat, 17 Oct 2015 22:41:02 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Martin , Robin Murphy , Stefan Wahren Subject: [PATCH 4.1 118/202] [PATCH REPOST] serial/amba-pl011: Disable interrupts around TX softirq Date: Sat, 17 Oct 2015 18:58:21 -0700 Message-Id: <20151018014907.288182903@linuxfoundation.org> In-Reply-To: <20151018014901.946875729@linuxfoundation.org> References: <20151018014901.946875729@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Martin pl011_tx_softirq() currently uses spin_{,un}lock(), which are not sufficient to inhibit pl011_int() from being triggered by a local IRQ and trying to re-take the same lock. This can lead to deadlocks. This patch uses the _irq() locking variants instead to ensure that pl011_int() handling for a given port is deferred until any pl011_tx_softirq() work for that port is complete. Notes for stable: This patch fixes an issue that is fixed by the following upstream commit, which is a more substantial rewrite of the affected code, fixing multiple, mostly more minor issues: 1e84d22322ceed4767db1e5342c830dd60c8210f serial/amba-pl011: Refactor and simplify TX FIFO handling The upstream patch was rejected for stable on the reasonable grounds that it was too big and complex a patch. The original buggy code was merged in v4.1, and the rewrite was merged in v4.2, leaving only v4.1 affected. This patch replaces the 1e84d22, for 4.1.x only. Fixes: 734745caeb9f serial/amba-pl011: Activate TX IRQ passively Signed-off-by: Dave Martin Tested-by: Robin Murphy Tested-by: Stefan Wahren Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/amba-pl011.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1360,9 +1360,9 @@ static void pl011_tx_softirq(struct work struct uart_amba_port *uap = container_of(dwork, struct uart_amba_port, tx_softirq_work); - spin_lock(&uap->port.lock); + spin_lock_irq(&uap->port.lock); while (pl011_tx_chars(uap)) ; - spin_unlock(&uap->port.lock); + spin_unlock_irq(&uap->port.lock); } static void pl011_tx_irq_seen(struct uart_amba_port *uap)