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    Subject[tip:perf/core] kprobes: Update document about irq disabled state in kprobe handler
    Commit-ID:  0f55a2f3d496133dd22f1e4e49fb7301da87c7bb
    Gitweb: http://git.kernel.org/tip/0f55a2f3d496133dd22f1e4e49fb7301da87c7bb
    Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    AuthorDate: Thu, 14 Oct 2010 12:10:18 +0900
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Thu, 14 Oct 2010 08:55:27 +0200

    kprobes: Update document about irq disabled state in kprobe handler

    Update kprobes.txt about interrupts disabled state inside
    kprobes handlers, because optimized probe/boosted kretprobe
    run without disabling interrrupts on x86.

    Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Rusty Russell <rusty@rustcorp.com.au>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: 2nddept-manager@sdl.hitachi.co.jp
    LKML-Reference: <20101014031018.4100.64883.stgit@ltc236.sdl.hitachi.co.jp>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    Documentation/kprobes.txt | 8 +++++---
    1 files changed, 5 insertions(+), 3 deletions(-)

    diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
    index 1762b81..741fe66 100644
    --- a/Documentation/kprobes.txt
    +++ b/Documentation/kprobes.txt
    @@ -542,9 +542,11 @@ Kprobes does not use mutexes or allocate memory except during
    registration and unregistration.

    Probe handlers are run with preemption disabled. Depending on the
    -architecture, handlers may also run with interrupts disabled. In any
    -case, your handler should not yield the CPU (e.g., by attempting to
    -acquire a semaphore).
    +architecture and optimization state, handlers may also run with
    +interrupts disabled (e.g., kretprobe handlers and optimized kprobe
    +handlers run without interrupt disabled on x86/x86-64). In any case,
    +your handler should not yield the CPU (e.g., by attempting to acquire
    +a semaphore).

    Since a return probe is implemented by replacing the return
    address with the trampoline's address, stack backtraces and calls

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