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    Subject[PATCH 1/2] perf: find_get_context: fix the per-cpu-counter check
    If task == NULL, find_get_context() should always check that cpu
    is correct.

    Afaics, the bug was introduced by 38a81da2 "perf events: Clean up
    pid passing", but even before that commit "&& cpu != -1" was not
    exactly right, -ESRCH from find_task_by_vpid() is not accurate.

    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    ---

    kernel/perf_event.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- git/kernel/perf_event.c~1_find_get_context 2011-01-14 18:21:05.000000000 +0100
    +++ git/kernel/perf_event.c 2011-01-18 16:56:40.000000000 +0100
    @@ -2228,7 +2228,7 @@ find_get_context(struct pmu *pmu, struct
    unsigned long flags;
    int ctxn, err;

    - if (!task && cpu != -1) {
    + if (!task) {
    /* Must be root to operate on a CPU event: */
    if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
    return ERR_PTR(-EACCES);


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