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c6317bc7c5
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> Cc: <stable@vger.kernel.org> #4.2+ Signed-off-by: Vineet Gupta <vgupta@synopsys.com> |
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