On Tue, Aug 16, 2022 at 05:11:03PM +0800, Yang Jihong wrote:The v4 patch only corrects the commit message because it is not determined whether to check the software event.
perf_output_read_group may respond to IPI request of other cores and invoke
__perf_install_in_context function. As a result, hwc configuration is modified.
As a result, the hwc configuration is modified, causing inconsistency and
unexpected consequences.
read_pmevcntrn+0x1e4/0x1ec arch/arm64/kernel/perf_event.c:423
armv8pmu_read_evcntr arch/arm64/kernel/perf_event.c:467 [inline]
armv8pmu_read_hw_counter arch/arm64/kernel/perf_event.c:475 [inline]
armv8pmu_read_counter+0x10c/0x1f0 arch/arm64/kernel/perf_event.c:528
armpmu_event_update+0x9c/0x1bc drivers/perf/arm_pmu.c:247
armpmu_read+0x24/0x30 drivers/perf/arm_pmu.c:264
perf_output_read_group+0x4cc/0x71c kernel/events/core.c:6806
perf_output_read+0x78/0x1c4 kernel/events/core.c:6845
perf_output_sample+0xafc/0x1000 kernel/events/core.c:6892
__perf_event_output kernel/events/core.c:7273 [inline]
perf_event_output_forward+0xd8/0x130 kernel/events/core.c:7287
__perf_event_overflow+0xbc/0x20c kernel/events/core.c:8943
perf_swevent_overflow kernel/events/core.c:9019 [inline]
perf_swevent_event+0x274/0x2c0 kernel/events/core.c:9047
do_perf_sw_event kernel/events/core.c:9160 [inline]
___perf_sw_event+0x150/0x1b4 kernel/events/core.c:9191
__perf_sw_event+0x58/0x7c kernel/events/core.c:9203
perf_sw_event include/linux/perf_event.h:1177 [inline]
Interrupts is not disabled when perf_output_read_group reads PMU counter.
s/is/are/ due to 'interrupts' being plural
Anyway, yes, I suppose this is indeed so. That code expects to run with
IRQs disabled but in the case of software events that isn't so.