From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120614235626.897774272@linuxfoundation.org> Date: Thu, 14 Jun 2012 16:56:57 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, AnilKumar Ch , Wolfgang Grandegger , Marc Kleine-Budde Subject: [ 34/42] can: c_can: fix race condition in c_can_open() In-Reply-To: <20120614235636.GA5275@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: AnilKumar Ch commit f461f27a4436dbe691908fe08b867ef888848cc3 upstream. Fix the issue of C_CAN interrupts getting disabled forever when canconfig utility is used multiple times. According to NAPI usage we disable all the hardware interrupts in ISR and re-enable them in poll(). Current implementation calls napi_enable() after hardware interrupts are enabled. If we get any interrupts between these two steps then we do not process those interrupts because napi is not enabled. Mostly these interrupts come because of STATUS is not 0x7 or ERROR interrupts. If napi_enable() happens before HW interrupts enabled then c_can_poll() function will be called eventual re-enabling. This patch moves the napi_enable() call before interrupts enabled. Signed-off-by: AnilKumar Ch Acked-by: Wolfgang Grandegger Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/c_can/c_can.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/net/can/c_can/c_can.c +++ b/drivers/net/can/c_can/c_can.c @@ -1064,10 +1064,11 @@ static int c_can_open(struct net_device goto exit_irq_fail; } + napi_enable(&priv->napi); + /* start the c_can controller */ c_can_start(dev); - napi_enable(&priv->napi); netif_start_queue(dev); return 0;