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    Subject[tip:perf/core] perf: Fix task refcount bugs
    Commit-ID:  e7d0bc047548d76feee6b23f7d3d9da927189a50
    Gitweb: http://git.kernel.org/tip/e7d0bc047548d76feee6b23f7d3d9da927189a50
    Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
    AuthorDate: Thu, 14 Oct 2010 16:54:51 +0200
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Mon, 18 Oct 2010 19:58:52 +0200

    perf: Fix task refcount bugs

    Currently it looks like find_lively_task_by_vpid() takes a task ref
    and relies on find_get_context() to drop it.

    The problem is that perf_event_create_kernel_counter() shouldn't be
    dropping task refs.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
    Acked-by: Matt Helsley <matthltc@us.ibm.com>
    LKML-Reference: <20101014203625.278436085@chello.nl>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    kernel/perf_event.c | 7 ++++---
    1 files changed, 4 insertions(+), 3 deletions(-)

    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index 346dc0e..f928878 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -2190,11 +2190,9 @@ retry:
    }
    }

    - put_task_struct(task);
    return ctx;

    errout:
    - put_task_struct(task);
    return ERR_PTR(err);
    }

    @@ -5602,7 +5600,7 @@ SYSCALL_DEFINE5(perf_event_open,
    ctx = find_get_context(pmu, task, cpu);
    if (IS_ERR(ctx)) {
    err = PTR_ERR(ctx);
    - goto err_group_fd;
    + goto err_task;
    }

    /*
    @@ -5698,6 +5696,9 @@ SYSCALL_DEFINE5(perf_event_open,

    err_context:
    put_ctx(ctx);
    +err_task:
    + if (task)
    + put_task_struct(task);
    err_group_fd:
    fput_light(group_file, fput_needed);
    free_event(event);

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