Messages in this thread |  | | | Date | Tue, 17 May 2011 23:27:34 +0200 | | From | Ingo Molnar <> | | Subject | Re: [PATCH 1/3] comm: Introduce comm_lock spinlock to protect task->comm access |
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* John Stultz <john.stultz@linaro.org> wrote:
> The implicit rules for current->comm access being safe without locking are no > longer true. Accessing current->comm without holding the task lock may result > in null or incomplete strings (however, access won't run off the end of the > string).
This is rather unfortunate - task->comm is used in a number of performance critical codepaths such as tracing.
Why does this matter so much? A NULL string is not a big deal.
Note, since task->comm is 16 bytes there's the CMPXCHG16B instruction on x86 which could be used to update it atomically, should atomicity really be desired.
Thanks,
Ingo
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