Messages in this thread | | | Date | Sun, 29 Aug 2010 21:38:27 +0300 | Subject | Re: [PATCH 05/11] x86-64: Disable preemption when using TS_USEDFPU | From | Pekka Enberg <> |
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On Sat, Aug 28, 2010 at 7:04 PM, Brian Gerst <brgerst@gmail.com> wrote: > Consolidates code and fixes the below race for 64-bit. > > commit 9fa2f37bfeb798728241cc4a19578ce6e4258f25 > Author: torvalds <torvalds> > Date: Tue Sep 2 07:37:25 2003 +0000 > > Be a lot more careful about TS_USEDFPU and preemption > > We had some races where we testecd (or set) TS_USEDFPU together > with sequences that depended on the setting (like clearing or > setting the TS flag in %cr0) and we could be preempted in between, > which screws up the FPU state, since preemption will itself change > USEDFPU and the TS flag. > > This makes it a lot more explicit: the "internal" low-level FPU > functions ("__xxxx_fpu()") all require preemption to be disabled, > and the exported "real" functions will make sure that is the case. > > One case - in __switch_to() - was switched to the non-preempt-safe > internal version, since the scheduler itself has already disabled > preemption. > > BKrev: 3f5448b5WRiQuyzAlbajs3qoQjSobw > > Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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