Re: Robust futexes

From: Daniel Walker
Date: Fri Feb 17 2006 - 10:45:40 EST


On Fri, 2006-02-17 at 15:57 +1100, Rusty Russell wrote:
> Hi Ingo, all,
>
> Noticed (via LWN, hence the delay) your robust futex work. Have you
> considered the less-perfect, but simpler option of simply having futex
> calls which tell the kernel that the u32 value is in fact the holder's
> TID?
>
> In this case, you don't get perfect robustness when TID wrap occurs:
> the kernel won't know that the lock holder is dead. However, it's
> simple, and telling the kernel that the lock is the tid allows the
> kernel to do prio inheritence etc. in future.

I think this was Todd Kneisel's approach . His version was vma
scanning, which is what Ingo is trying to replace. It just used the
current u32 value .

Daniel

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