From 56a94f13919c0db5958611b388e1581b4852f3c9 Mon Sep 17 00:00:00 2001 From: Damian Eppel Date: Fri, 26 Jun 2015 15:23:04 +0200 Subject: 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] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 40.786747] [] (show_stack) from [] (dump_stack+0x70/0xbc) [ 40.786767] [] (dump_stack) from [] (kmem_cache_alloc+0xd8/0x170) [ 40.786785] [] (kmem_cache_alloc) from [] (request_threaded_irq+0x64/0x128) [ 40.786804] [] (request_threaded_irq) from [] (exynos4_local_timer_setup+0xc0/0x13c) [ 40.786820] [] (exynos4_local_timer_setup) from [] (exynos4_mct_cpu_notify+0x30/0xa8) [ 40.786838] [] (exynos4_mct_cpu_notify) from [] (notifier_call_chain+0x44/0x84) [ 40.786857] [] (notifier_call_chain) from [] (__cpu_notify+0x28/0x44) [ 40.786873] [] (__cpu_notify) from [] (secondary_start_kernel+0xec/0x150) [ 40.786886] [] (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 Reviewed-by: Krzysztof Kozlowski Tested-by: Krzysztof Kozlowski Tested-by: Marcin Jabrzyk Signed-off-by: Damian Eppel 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 Cc: diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c index 935b059..9064ff7 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); -- cgit v0.10.2 From 24bfcb100959c8641a627b5604d967243f8f240c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 26 Jun 2015 22:08:38 +0200 Subject: timer: Fix hotplug regression The recent timer wheel rework removed the get/put_cpu_var() pair in the hotplug migration code, which results in: BUG: using smp_processor_id() in preemptible [00000000] code: hib.sh/2845 ... [] timer_cpu_notify+0x53/0x12 That hunk is a leftover from an earlier iteration and went unnoticed so far. Restore the previous code which was obviously correct. Fixes: 0eeda71bc30d 'timer: Replace timer base by a cpu index' Reported-and_tested-by: Borislav Petkov Signed-off-by: Thomas Gleixner diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 520499d..5e097fa 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1566,7 +1566,7 @@ static void migrate_timers(int cpu) BUG_ON(cpu_online(cpu)); old_base = per_cpu_ptr(&tvec_bases, cpu); - new_base = this_cpu_ptr(&tvec_bases); + new_base = get_cpu_ptr(&tvec_bases); /* * The caller is globally serialized and nobody else * takes two locks at once, deadlock is not possible. @@ -1590,6 +1590,7 @@ static void migrate_timers(int cpu) spin_unlock(&old_base->lock); spin_unlock_irq(&new_base->lock); + put_cpu_ptr(&tvec_bases); } static int timer_cpu_notify(struct notifier_block *self, -- cgit v0.10.2 From 65f26062cd8f653dac11d3c00d326f7f57b5e098 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 1 Jul 2015 09:57:35 +0200 Subject: time: Remove development rules from Kbuild/Makefile time.o gets rebuilt unconditionally due to a leftover Makefile rule which was placed there for development purposes. Remove it along with the commented out always rule in the toplevel Kbuild file. Fixes: 0a227985d4a9 'time: Move timeconst.h into include/generated' Reported-by; Stephen Boyd Signed-off-by: Thomas Gleixner Cc: Nicholas Mc Guire diff --git a/Kbuild b/Kbuild index df99a5f..f55cefd 100644 --- a/Kbuild +++ b/Kbuild @@ -52,7 +52,6 @@ $(obj)/$(bounds-file): kernel/bounds.s FORCE timeconst-file := include/generated/timeconst.h -#always += $(timeconst-file) targets += $(timeconst-file) quiet_cmd_gentimeconst = GEN $@ diff --git a/kernel/time/Makefile b/kernel/time/Makefile index ffc4cc3..49eca0b 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -12,5 +12,3 @@ obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o tick-sched.o obj-$(CONFIG_TIMER_STATS) += timer_stats.o obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o obj-$(CONFIG_TEST_UDELAY) += test_udelay.o - -$(obj)/time.o: $(objtree)/include/config/ -- cgit v0.10.2