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    SubjectRe: [PATCH 1/3] comm: Introduce comm_lock spinlock to protect task->comm access
    On Tue, 17 May 2011, Peter Zijlstra wrote:

    > The changelog also fails to mention _WHY_ this is no longer true. Nor
    > does it treat why making it true again isn't an option.

    It's been true since:

    Author: john stultz <>
    Date: Mon Dec 14 18:00:05 2009 -0800

    procfs: allow threads to rename siblings via /proc/pid/tasks/tid/comm

    Although at the time it appears that nobody was concerned about races so
    proper syncronization was never implemented. We always had the
    prctl(PR_SET_NAME) so the majority of comm reads, those to current,
    required no locking, but this commit changed that. The remainder of comm
    dereferences always required task_lock() and the helper get_task_comm() to
    read the string into a (usually stack-allocated) buffer.

    > Who is changing another task's comm? That's just silly.

    I agree, and I suggested taking write privileges away from /proc/pid/comm,
    but others find that it is useful to be able to differentiate between
    threads in the same thread group without using the prctl() for debugging?

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      Last update: 2011-05-18 00:59    [W:0.020 / U:11.276 seconds]
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