From: Maxime Ripard Date: Tue, 18 Nov 2014 22:59:33 +0000 (+0100) Subject: clockevent: sun4i: Fix race condition in the probe code X-Git-Tag: v3.12.35~47 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1b0a21003bd3b81a0b935f51f4e6988910cb0ae1;p=thirdparty%2Fkernel%2Fstable.git clockevent: sun4i: Fix race condition in the probe code commit 6bab4a8a1888729f17f4923cc5867e4674f66333 upstream. The interrupts were activated and the handler registered before the clockevent was registered in the probe function. The interrupt handler, however, was making the assumption that the clockevent device was registered. That could cause a null pointer dereference if the timer interrupt was firing during this narrow window. Fix that by moving the clockevent registration before the interrupt is enabled. Reported-by: Roman Byshko Signed-off-by: Maxime Ripard Signed-off-by: Daniel Lezcano Signed-off-by: Jiri Slaby --- diff --git a/drivers/clocksource/sun4i_timer.c b/drivers/clocksource/sun4i_timer.c index 8ead0258740a8..4fe6ac85ea1db 100644 --- a/drivers/clocksource/sun4i_timer.c +++ b/drivers/clocksource/sun4i_timer.c @@ -177,6 +177,11 @@ static void __init sun4i_timer_init(struct device_node *node) writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M), timer_base + TIMER_CTL_REG(0)); + sun4i_clockevent.cpumask = cpumask_of(0); + + clockevents_config_and_register(&sun4i_clockevent, rate, 0x1, + 0xffffffff); + ret = setup_irq(irq, &sun4i_timer_irq); if (ret) pr_warn("failed to setup irq %d\n", irq); @@ -184,11 +189,6 @@ static void __init sun4i_timer_init(struct device_node *node) /* Enable timer0 interrupt */ val = readl(timer_base + TIMER_IRQ_EN_REG); writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG); - - sun4i_clockevent.cpumask = cpumask_of(0); - - clockevents_config_and_register(&sun4i_clockevent, rate, 0x1, - 0xffffffff); } CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer", sun4i_timer_init);