Oleg Nesterov 7575637ab2 x86, fpu: Fix math_state_restore() race with kernel_fpu_begin() ... math_state_restore() can race with kernel_fpu_begin() if irq comes right after __thread_fpu_begin(), __save_init_fpu() will overwrite fpu->state we are going to restore. Add 2 simple helpers, kernel_fpu_disable() and kernel_fpu_enable() which simply set/clear in_kernel_fpu, and change math_state_restore() to exclude kernel_fpu_begin() in between. Alternatively we could use local_irq_save/restore, but probably these new helpers can have more users. Perhaps they should disable/enable preemption themselves, in this case we can remove preempt_disable() in __restore_xstate_sig(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: matt.fleming@intel.com Cc: bp@suse.de Cc: pbonzini@redhat.com Cc: luto@amacapital.net Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Suresh Siddha <sbsiddha@gmail.com> Link: http://lkml.kernel.org/r/20150115192028.GD27332@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>		2015-01-20 13:53:07 +01:00
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asm	x86, fpu: Fix math_state_restore() race with kernel_fpu_begin()	2015-01-20 13:53:07 +01:00
uapi/asm	Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-12-19 13:18:31 -08:00