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    Subject[PATCH AUTOSEL 4.14 30/30] perf/core: Fix creating kernel counters for PMUs that override event->cpu
    Date
    From: Leonard Crestez <leonard.crestez@nxp.com>

    [ Upstream commit 4ce54af8b33d3e21ca935fc1b89b58cbba956051 ]

    Some hardware PMU drivers will override perf_event.cpu inside their
    event_init callback. This causes a lockdep splat when initialized through
    the kernel API:

    WARNING: CPU: 0 PID: 250 at kernel/events/core.c:2917 ctx_sched_out+0x78/0x208
    pc : ctx_sched_out+0x78/0x208
    Call trace:
    ctx_sched_out+0x78/0x208
    __perf_install_in_context+0x160/0x248
    remote_function+0x58/0x68
    generic_exec_single+0x100/0x180
    smp_call_function_single+0x174/0x1b8
    perf_install_in_context+0x178/0x188
    perf_event_create_kernel_counter+0x118/0x160

    Fix this by calling perf_install_in_context with event->cpu, just like
    perf_event_open

    Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: Mark Rutland <mark.rutland@arm.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
    Cc: Frank Li <Frank.li@nxp.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Will Deacon <will@kernel.org>
    Link: https://lkml.kernel.org/r/c4ebe0503623066896d7046def4d6b1e06e0eb2e.1563972056.git.leonard.crestez@nxp.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/events/core.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index 3d4eb6f840eba..ea4f3f7a0c6f3 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -10474,7 +10474,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
    goto err_unlock;
    }

    - perf_install_in_context(ctx, event, cpu);
    + perf_install_in_context(ctx, event, event->cpu);
    perf_unpin_context(ctx);
    mutex_unlock(&ctx->mutex);

    --
    2.20.1
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