Re: [PATCH] perf tools: avoid possible race condition in copyfile

[Ingo Molnar]

* Milos Vyletel <milos@xxxxxxxxxx> wrote:

> Use unique temporary files when copying to buildid dir to prevent races
> in case multiple instances are trying to copy same file. This is done by
> 
> - creating template in form <path>/.<filename>.XXXXXX where the suffix is
>   used by mkstemp() to create unique file
> - change file mode
> - copy content
> - if successful link temp file to target file
> - unlink temp file
> 
> At this point the only file left at target path should be the desired
> one either created by us or other instance if we raced. This should also
> prevent not yet fully copied files to be visible to to other perf
> instances that could try to parse them.
> 
> On top of that slow_copyfile no longer needs to deal with file mode when
> creating file since temporary file is already created and mode is set.
> 
> Signed-off-by: Milos Vyletel <milos@xxxxxxxxxx>

Ok, that looks nice!

Assuming it passes testing you can add my ack to it:

  Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>

Is there any other place in tools/perf where we are using file locking or racy 
shared access to the same file(s)?

Thanks,

	Ingo
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