Messages in this thread Patch in this message | | | From | Vineet Gupta <> | Subject | [PATCH 3/3] ARCv2: perf: Ensure perf intr gets enabled on all cores | Date | Fri, 11 Dec 2015 16:49:13 +0530 |
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This was the second perf intr issue
perf sampling on multicore requires intr to be enabled on all cores. ARC perf probe code used helper arc_request_percpu_irq() which calls - request_percpu_irq() on core0 - enable_percpu_irq() on all all cores (including core0)
genirq requires that request be made ahead of enable call. However if perf probe happened on non core0 (observed on a 3.18 kernel), enable would get called ahead of request, failing obviously and rendering perf intr disabled on all such cores
[ 11.120000] 1 ARC perf : 8 counters (48 bits), 113 conditions, [overflow IRQ support] [ 11.130000] 1 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 3 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 2 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 0 =====> request_percpu_irq() IRQ 20 [ 11.140000] 0 -----> enable_percpu_irq() IRQ 20
Fix this fragility, by calling request_percpu_irq() on whatever core calls probe (there is no requirement on which core calls this anyways) and then calling enable on each cores.
Interestingly this started as invesigation of STAR 9000838902: "sporadically IRQs enabled on perf prob"
which was about occassional boot spew as request_percpu_irq got called non-locally (from an IPI), and re-enabled interrupts in following path proc_mkdir -> spin_unlock_irq()
which the irq work code didn't like.
| ARC perf : 8 counters (48 bits), 113 conditions, [overflow IRQ support] | | BUG: failure at ../kernel/irq_work.c:135/irq_work_run_list()! | CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.18.10-01127-g285efb8e66d1 #2 | | Stack Trace: | arc_unwind_core.constprop.1+0x94/0x104 | dump_stack+0x62/0x98 | irq_work_run_list+0xb0/0xb4 | irq_work_run+0x22/0x3c | do_IPI+0x74/0x9c | handle_irq_event_percpu+0x34/0x164 | handle_percpu_irq+0x58/0x78 | generic_handle_irq+0x1e/0x2c | arch_do_IRQ+0x3c/0x60 | ret_from_exception+0x0/0x8
Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- arch/arc/kernel/perf_event.c | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-)
diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c index 0c08bb1ce15a..8b134cfe5e1f 100644 --- a/arch/arc/kernel/perf_event.c +++ b/arch/arc/kernel/perf_event.c @@ -428,12 +428,11 @@ static irqreturn_t arc_pmu_intr(int irq, void *dev) #endif /* CONFIG_ISA_ARCV2 */ -void arc_cpu_pmu_irq_init(void) +static void arc_cpu_pmu_irq_init(void *data) { - struct arc_pmu_cpu *pmu_cpu = this_cpu_ptr(&arc_pmu_cpu); + int irq = *(int *)data; - arc_request_percpu_irq(arc_pmu->irq, smp_processor_id(), arc_pmu_intr, - "ARC perf counters", pmu_cpu); + enable_percpu_irq(irq, IRQ_TYPE_NONE); /* Clear all pending interrupt flags */ write_aux_reg(ARC_REG_PCT_INT_ACT, 0xffffffff); @@ -515,7 +514,6 @@ static int arc_pmu_device_probe(struct platform_device *pdev) if (has_interrupts) { int irq = platform_get_irq(pdev, 0); - unsigned long flags; if (irq < 0) { pr_err("Cannot get IRQ number for the platform\n"); @@ -524,24 +522,12 @@ static int arc_pmu_device_probe(struct platform_device *pdev) arc_pmu->irq = irq; - /* - * arc_cpu_pmu_irq_init() needs to be called on all cores for - * their respective local PMU. - * However we use opencoded on_each_cpu() to ensure it is called - * on core0 first, so that arc_request_percpu_irq() sets up - * AUTOEN etc. Otherwise enable_percpu_irq() fails to enable - * perf IRQ on non master cores. - * see arc_request_percpu_irq() - */ - preempt_disable(); - local_irq_save(flags); - arc_cpu_pmu_irq_init(); - local_irq_restore(flags); - smp_call_function((smp_call_func_t)arc_cpu_pmu_irq_init, 0, 1); - preempt_enable(); - - /* Clean all pending interrupt flags */ - write_aux_reg(ARC_REG_PCT_INT_ACT, 0xffffffff); + /* intc map function ensures irq_set_percpu_devid() called */ + request_percpu_irq(irq, arc_pmu_intr, "ARC perf counters", + this_cpu_ptr(&arc_pmu_cpu)); + + on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1); + } else arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT; -- 1.9.1
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