Messages in this thread Patch in this message |  | | Date | Thu, 19 Feb 2015 03:32:24 -0800 | From | tip-bot for Oleg Nesterov <> | Subject | [tip:x86/fpu] x86/fpu: Don't reset thread.fpu_counter |
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Commit-ID: a9241ea5fd709fc935dade130f4e3b2612bbe9e3 Gitweb: http://git.kernel.org/tip/a9241ea5fd709fc935dade130f4e3b2612bbe9e3 Author: Oleg Nesterov <oleg@redhat.com> AuthorDate: Fri, 6 Feb 2015 15:01:58 -0500 Committer: Borislav Petkov <bp@suse.de> CommitDate: Thu, 19 Feb 2015 11:12:40 +0100
x86/fpu: Don't reset thread.fpu_counter
The "else" branch clears ->fpu_counter as a remnant of the lazy FPU usage counting:
e07e23e1fd30 ("[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> --- arch/x86/kernel/i387.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index a9a4229..4d0db9e 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -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);
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