Re: [PATCH 01/12] rwsem: test for no active locks in __rwsem_do_wake undo code

[David Howells]

Michel Lespinasse <walken@xxxxxxxxxx> wrote:

> If there are no active threasd using a semaphore, it is always correct to
> unqueue blocked threads. This seems to be what was intended in the undo code.
> 
> What was done instead, was to look for a sem count of zero - this is an
> impossible situation, given that at least one thread is known to be queued
> on the semaphore. The code might be correct as written, but it's hard to
> reason about and it's not what was intended (otherwise the goto out would
> have been unconditional).
> 
> Go for checking the active count - the alternative is not worth the headache.

I think this is a definite bug fix, so I've sent it upstream in advance.

David
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