lkml.org 
[lkml]   [2015]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 7/8] x86,fpu: use disable_task_lazy_fpu_restore helper
    On Fri, Feb 06, 2015 at 03:02:04PM -0500, riel@redhat.com wrote:
    > From: Rik van Riel <riel@redhat.com>
    >
    > Replace magic assignments of fpu.last_cpu = ~0 with more explicit
    > disable_task_lazy_fpu_restore calls.
    >
    > This also fixes the lazy FPU restore disabling in drop_fpu, which
    > only really works when !use_eager_fpu(). This is fine for now,
    > because fpu_lazy_restore() is only used when !use_eager_fpu()
    > currently, but we may want to expand that.

    Sorry, I can't follow here. The only non-trivial change below is in
    arch_dup_task_struct(). Please clarify.

    [ leaving in the rest for context ]

    >
    > Signed-off-by: Rik van Riel <riel@redhat.com>
    > ---
    > arch/x86/include/asm/fpu-internal.h | 4 ++--
    > arch/x86/kernel/i387.c | 2 +-
    > arch/x86/kernel/process.c | 2 +-
    > 3 files changed, 4 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
    > index 04063751ac80..06af286593d7 100644
    > --- a/arch/x86/include/asm/fpu-internal.h
    > +++ b/arch/x86/include/asm/fpu-internal.h
    > @@ -440,7 +440,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
    > new->thread.fpu_counter > 5);
    > if (__thread_has_fpu(old)) {
    > if (!__save_init_fpu(old))
    > - old->thread.fpu.last_cpu = ~0;
    > + task_disable_lazy_fpu_restore(old);
    > else
    > old->thread.fpu.last_cpu = cpu;
    > old->thread.fpu.has_fpu = 0; /* But leave fpu_owner_task! */
    > @@ -454,7 +454,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
    > stts();
    > } else {
    > old->thread.fpu_counter = 0;
    > - old->thread.fpu.last_cpu = ~0;
    > + task_disable_lazy_fpu_restore(old);
    > if (fpu.preload) {
    > new->thread.fpu_counter++;
    > if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))
    > diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
    > index 8e070a6c30e5..8416b5f85806 100644
    > --- a/arch/x86/kernel/i387.c
    > +++ b/arch/x86/kernel/i387.c
    > @@ -250,7 +250,7 @@ int init_fpu(struct task_struct *tsk)
    > if (tsk_used_math(tsk)) {
    > if (cpu_has_fpu && tsk == current)
    > unlazy_fpu(tsk);
    > - tsk->thread.fpu.last_cpu = ~0;
    > + task_disable_lazy_fpu_restore(tsk);
    > return 0;
    > }
    >
    > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
    > index dd9a069a5ec5..83480373a642 100644
    > --- a/arch/x86/kernel/process.c
    > +++ b/arch/x86/kernel/process.c
    > @@ -68,8 +68,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
    >
    > dst->thread.fpu_counter = 0;
    > dst->thread.fpu.has_fpu = 0;
    > - dst->thread.fpu.last_cpu = ~0;
    > dst->thread.fpu.state = NULL;
    > + task_disable_lazy_fpu_restore(dst);
    > if (tsk_used_math(src)) {
    > int err = fpu_alloc(&dst->thread.fpu);
    > if (err)
    > --
    > 1.9.3
    >
    > --
    > 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/
    >

    --
    Regards/Gruss,
    Boris.

    ECO tip #101: Trim your mails when you reply.
    --


    \
     
     \ /
      Last update: 2015-02-17 10:21    [W:2.801 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site