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authorDamian Eppel <d.eppel@samsung.com>2015-06-26 16:23:04 +0300
committerThomas Gleixner <tglx@linutronix.de>2015-06-26 22:53:01 +0300
commit56a94f13919c0db5958611b388e1581b4852f3c9 (patch)
tree765497df356a545fb036c304d50555c9b3075ebe /drivers/clocksource
parent407a2c720556e8e340e06f6a7174f5d6d80cf9ea (diff)
downloadlinux-56a94f13919c0db5958611b388e1581b4852f3c9.tar.xz
clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier
Whilst testing cpu hotplug events on kernel configured with DEBUG_PREEMPT and DEBUG_ATOMIC_SLEEP we get following BUG message, caused by calling request_irq() and free_irq() in the context of hotplug notification (which is in this case atomic context). [ 40.785859] CPU1: Software reset [ 40.786660] BUG: sleeping function called from invalid context at mm/slub.c:1241 [ 40.786668] in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/1 [ 40.786678] Preemption disabled at:[< (null)>] (null) [ 40.786681] [ 40.786692] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.19.0-rc4-00024-g7dca860 #36 [ 40.786698] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [ 40.786728] [<c0014a00>] (unwind_backtrace) from [<c0011980>] (show_stack+0x10/0x14) [ 40.786747] [<c0011980>] (show_stack) from [<c0449ba0>] (dump_stack+0x70/0xbc) [ 40.786767] [<c0449ba0>] (dump_stack) from [<c00c6124>] (kmem_cache_alloc+0xd8/0x170) [ 40.786785] [<c00c6124>] (kmem_cache_alloc) from [<c005d6f8>] (request_threaded_irq+0x64/0x128) [ 40.786804] [<c005d6f8>] (request_threaded_irq) from [<c0350b8c>] (exynos4_local_timer_setup+0xc0/0x13c) [ 40.786820] [<c0350b8c>] (exynos4_local_timer_setup) from [<c0350ca8>] (exynos4_mct_cpu_notify+0x30/0xa8) [ 40.786838] [<c0350ca8>] (exynos4_mct_cpu_notify) from [<c003b330>] (notifier_call_chain+0x44/0x84) [ 40.786857] [<c003b330>] (notifier_call_chain) from [<c0022fd4>] (__cpu_notify+0x28/0x44) [ 40.786873] [<c0022fd4>] (__cpu_notify) from [<c0013714>] (secondary_start_kernel+0xec/0x150) [ 40.786886] [<c0013714>] (secondary_start_kernel) from [<40008764>] (0x40008764) Interrupts cannot be requested/freed in the CPU_STARTING/CPU_DYING notifications which run on the hotplugged cpu with interrupts and preemption disabled. To avoid the issue, request the interrupts for all possible cpus in the boot code. The interrupts are marked NO_AUTOENABLE to avoid a racy request_irq/disable_irq() sequence. The flag prevents the request_irq() code from enabling the interrupt immediately. The interrupt is then enabled in the CPU_STARTING notifier of the hotplugged cpu and again disabled with disable_irq_nosync() in the CPU_DYING notifier. [ tglx: Massaged changelog to match the patch ] Fixes: 7114cd749a12 ("clocksource: exynos_mct: use (request/free)_irq calls for local timer registration") Reported-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Tested-by: Marcin Jabrzyk <m.jabrzyk@samsung.com> Signed-off-by: Damian Eppel <d.eppel@samsung.com> Cc: m.szyprowski@samsung.com Cc: kyungmin.park@samsung.com Cc: daniel.lezcano@linaro.org Cc: kgene@kernel.org Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1435324984-7328-1-git-send-email-d.eppel@samsung.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/exynos_mct.c43
1 files changed, 30 insertions, 13 deletions
diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 935b05936dbd..9064ff743598 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -462,15 +462,12 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET);
if (mct_int_type == MCT_INT_SPI) {
- evt->irq = mct_irqs[MCT_L0_IRQ + cpu];
- if (request_irq(evt->irq, exynos4_mct_tick_isr,
- IRQF_TIMER | IRQF_NOBALANCING,
- evt->name, mevt)) {
- pr_err("exynos-mct: cannot register IRQ %d\n",
- evt->irq);
+
+ if (evt->irq == -1)
return -EIO;
- }
- irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));
+
+ irq_force_affinity(evt->irq, cpumask_of(cpu));
+ enable_irq(evt->irq);
} else {
enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0);
}
@@ -483,10 +480,12 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
static void exynos4_local_timer_stop(struct clock_event_device *evt)
{
evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
- if (mct_int_type == MCT_INT_SPI)
- free_irq(evt->irq, this_cpu_ptr(&percpu_mct_tick));
- else
+ if (mct_int_type == MCT_INT_SPI) {
+ if (evt->irq != -1)
+ disable_irq_nosync(evt->irq);
+ } else {
disable_percpu_irq(mct_irqs[MCT_L0_IRQ]);
+ }
}
static int exynos4_mct_cpu_notify(struct notifier_block *self,
@@ -518,7 +517,7 @@ static struct notifier_block exynos4_mct_cpu_nb = {
static void __init exynos4_timer_resources(struct device_node *np, void __iomem *base)
{
- int err;
+ int err, cpu;
struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);
struct clk *mct_clk, *tick_clk;
@@ -545,7 +544,25 @@ static void __init exynos4_timer_resources(struct device_node *np, void __iomem
WARN(err, "MCT: can't request IRQ %d (%d)\n",
mct_irqs[MCT_L0_IRQ], err);
} else {
- irq_set_affinity(mct_irqs[MCT_L0_IRQ], cpumask_of(0));
+ for_each_possible_cpu(cpu) {
+ int mct_irq = mct_irqs[MCT_L0_IRQ + cpu];
+ struct mct_clock_event_device *pcpu_mevt =
+ per_cpu_ptr(&percpu_mct_tick, cpu);
+
+ pcpu_mevt->evt.irq = -1;
+
+ irq_set_status_flags(mct_irq, IRQ_NOAUTOEN);
+ if (request_irq(mct_irq,
+ exynos4_mct_tick_isr,
+ IRQF_TIMER | IRQF_NOBALANCING,
+ pcpu_mevt->name, pcpu_mevt)) {
+ pr_err("exynos-mct: cannot register IRQ (cpu%d)\n",
+ cpu);
+
+ continue;
+ }
+ pcpu_mevt->evt.irq = mct_irq;
+ }
}
err = register_cpu_notifier(&exynos4_mct_cpu_nb);