Re: [PATCH] fix race in mark_mounts_for_expiry()
From: David Howells
Date: Wed May 18 2005 - 06:54:18 EST
Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> Do you think my original fix is wrong, or is this just cosmetics?
What you're doing is tricky. It's asking for a race. Admittedly, it may not
occur in the particular situation you're looking at, but can you always
guarantee that? Remember, it may be a race against some piece of code that's
not yet written, by an author who doesn't realise what _you_ are doing here
because their changeset doesn't intersect with yours.
Remember: you have, in effect, made the usage count on that structure
non-atomic.
I do something like that in rwsems and it's something I have to be very
careful about. The main reason I can get away with it is that the actual
implementation of rwsems is small and is located in a very restrictes set of
places and it's not intermingled with other stuff.
David
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