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x86/fpu: Don't reset thread.fpu_counter

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The "else" branch clears ->fpu_counter as a remnant of the lazy FPU
usage counting:

  e07e23e1fd ("[PATCH] non lazy "sleazy" fpu implementation")

However, switch_fpu_prepare() does this now so that else branch is
superfluous.

If we do use_eager_fpu(), then this has no effect. Otherwise, if we
actually wanted to prevent fpu preload after the context switch we would
need to reset it unconditionally, even if __thread_has_fpu().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1423252925-14451-2-git-send-email-riel@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Oleg Nesterov
2015-02-06 15:01:58 -05:00
committed by Borislav Petkov
parent bfa76d4957
commit a9241ea5fd
1 changed files with 1 additions and 2 deletions
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3
arch/x86/kernel/i387.c
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@@ -108,8 +108,7 @@ void unlazy_fpu(struct task_struct *tsk)
if (__thread_has_fpu(tsk)) {
__save_init_fpu(tsk);
__thread_fpu_end(tsk);
} else
tsk->thread.fpu_counter = 0;
}
preempt_enable();
}
EXPORT_SYMBOL(unlazy_fpu);