Re: [Xen-devel] [PATCH] xenconsole: Ensure exclusive access to console using locks

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Ian Campbell writes ("Re: [PATCH] xenconsole: Ensure exclusive access to 
console using locks"):
> I think the answer is to either not remove the lockfile

That is a bit messy (although not entirely wrong).

> or to do so _before_ dropping the lock, which makes the unlink
> itself the effective unlock point.

This is necessary but not sufficient.  With only that change:

  A  open flock    unlink    close

  B            open               flock  .o{ I have the lock }

  C                      open     flock  .o{ I have the lock }

B is mistaken because it olds an fd onto an unlinked file.

Ian.

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