Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] [RFC] Optimize select/poll by putting small data sets on the stack | Date | Wed, 4 Jan 2006 01:48:42 +0100 |
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On Wednesday 04 January 2006 01:43, Eric Dumazet wrote:
> And I would like to pinpoint that set_fd_set() implementation seems *buggy* > : > > It should not use __copy_to_user() but the real one (copy_to_user()) > because the calling thread could have slept in do_select() and another > thread played mm games during this sleep.
__ only skips the access_ok which checks the kernel/user boundary, and the kernel/user boundary doesn't change even while sleeping.
On very early 386s it did something more to work around a CPU bug, but that is racy on multithreaded processes in any case. Not really worth caring about.
Also I doubt any such machines are left in working condition. That old workaround code could be probably safely removed by now.
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