From: riel@redhat.com
To: oleg@redhat.com
Cc: dave.hansen@linux.intel.com, sbsiddha@gmail.com,
luto@amacapital.net, tglx@linutronix.de, mingo@kernel.org,
hpa@zytor.com, fenghua.yu@intel.com, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 1/8] x86, fpu: unlazy_fpu: don't reset thread.fpu_counter
Date: Fri, 6 Feb 2015 15:01:58 -0500 [thread overview]
Message-ID: <1423252925-14451-2-git-send-email-riel@redhat.com> (raw)
In-Reply-To: <1423252925-14451-1-git-send-email-riel@redhat.com>
From: Oleg Nesterov <oleg@redhat.com>
It is not clear why the "else" branch clears ->fpu_counter, this makes
no sense.
If 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>
---
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 47348653503a..c3b92c0975cd 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -122,8 +122,7 @@ 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);
--
1.9.3
next prev parent reply other threads:[~2015-02-06 20:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-06 20:01 [PATCH 0/8] x86,fpu: various small FPU cleanups and optimizations riel
2015-02-06 20:01 ` riel [this message]
2015-02-16 17:04 ` [PATCH 1/8] x86, fpu: unlazy_fpu: don't reset thread.fpu_counter Borislav Petkov
2015-02-16 17:58 ` Rik van Riel
2015-02-16 18:14 ` Oleg Nesterov
2015-02-16 18:16 ` Borislav Petkov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Don't " tip-bot for Oleg Nesterov
2015-02-06 20:01 ` [PATCH 2/8] x86, fpu: unlazy_fpu: don't do __thread_fpu_end() if use_eager_fpu() riel
2015-02-16 20:25 ` Borislav Petkov
2015-02-17 10:47 ` Oleg Nesterov
2015-02-17 12:09 ` Borislav Petkov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Don't " tip-bot for Oleg Nesterov
2015-02-06 20:02 ` [PATCH 3/8] x86, fpu: kill save_init_fpu(), change math_error() to use unlazy_fpu() riel
2015-02-16 21:09 ` Borislav Petkov
2015-02-16 21:30 ` Rik van Riel
2015-02-17 10:58 ` Oleg Nesterov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu() tip-bot for Oleg Nesterov
2015-02-06 20:02 ` [PATCH 4/8] x86,fpu: move lazy restore functions up a few lines riel
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Move " tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 5/8] x86,fpu: introduce task_disable_lazy_fpu_restore helper riel
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Introduce task_disable_lazy_fpu_restore() helper tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 6/8] x86,fpu: use an explicit if/else in switch_fpu_prepare riel
2015-02-17 8:44 ` Borislav Petkov
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Use an explicit if/ else in switch_fpu_prepare() tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 7/8] x86,fpu: use disable_task_lazy_fpu_restore helper riel
2015-02-17 9:00 ` Borislav Petkov
2015-02-17 11:04 ` Oleg Nesterov
2015-02-17 12:11 ` Borislav Petkov
2015-02-19 11:34 ` [tip:x86/fpu] x86/fpu: Use task_disable_lazy_fpu_restore() helper tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 8/8] x86,fpu: also check fpu_lazy_restore when use_eager_fpu riel
2015-02-19 11:34 ` [tip:x86/fpu] x86/fpu: Also check fpu_lazy_restore() when use_eager_fpu() tip-bot for Rik van Riel
2015-02-16 15:26 ` [PATCH 0/8] x86,fpu: various small FPU cleanups and optimizations Rik van Riel
2015-02-16 16:00 ` Borislav Petkov
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