From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 1/5] drivers-tty-pl011-irq-disable-madness.patch Date: Wed, 06 Feb 2013 17:06:09 -0500 Message-ID: <20130206220632.329615743@goodmis.org> References: <20130206220608.862416001@goodmis.org> Cc: Thomas Gleixner , Carsten Emde , John Kacur , To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:3920 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932189Ab3BFWGd (ORCPT ); Wed, 6 Feb 2013 17:06:33 -0500 Content-Disposition: inline; filename=0001-drivers-tty-pl011-irq-disable-madness.patch.patch Sender: linux-rt-users-owner@vger.kernel.org List-ID: From: Thomas Gleixner Cc: stable-rt@vger.kernel.org Signed-off-by: Thomas Gleixner Signed-off-by: Steven Rostedt --- drivers/tty/serial/amba-pl011.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 7cbb367..40356ae 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1754,13 +1754,19 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) clk_enable(uap->clk); - local_irq_save(flags); + /* + * local_irq_save(flags); + * + * This local_irq_save() is nonsense. If we come in via sysrq + * handling then interrupts are already disabled. Aside of + * that the port.sysrq check is racy on SMP regardless. + */ if (uap->port.sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock(&uap->port.lock); + locked = spin_trylock_irqsave(&uap->port.lock, flags); else - spin_lock(&uap->port.lock); + spin_lock_irqsave(&uap->port.lock, flags); /* * First save the CR then disable the interrupts @@ -1782,8 +1788,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) writew(old_cr, uap->port.membase + UART011_CR); if (locked) - spin_unlock(&uap->port.lock); - local_irq_restore(flags); + spin_unlock_irqrestore(&uap->port.lock, flags); clk_disable(uap->clk); } -- 1.7.10.4