Re: Change in functionality of futex() system call.

From: Eric Dumazet
Date: Mon Jun 06 2011 - 13:11:45 EST


Le lundi 06 juin 2011 Ã 19:05 +0200, Peter Zijlstra a Ãcrit :

> Dunno, using futexes on private file maps is stupid imo, its just asking
> for trouble, ro private file maps are even worse. Forcing the COW is the
> only sane answer in that it gives consistent results and 'breaks' silly
> expectations early instead of sometimes.
>
> Anyway, that's not really the issue here, as David uses MAP_SHARED (as
> one should if one is interested in the shared value).

Sure, but maybe another guy is 'stupid' and uses MAP_PRIVATE on its
read-only mappings. With old kernels this was working, and we were not
doing the COW.

(Note : the other process writes to the file, using MAP_SHARED)



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/