Re: [PATCH 1/3] comm: Introduce comm_lock spinlock to protecttask->comm access
From: Ingo Molnar
Date: Tue May 17 2011 - 17:28:14 EST
* John Stultz <john.stultz@xxxxxxxxxx> 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
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
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