Currently user_fpu_begin() has a single caller and it is not clear that why do we actually need it, and why we should not worry about preemption right after preempt_enable().
Signed-off-by: Oleg Nesterov <[email protected]> --- arch/x86/include/asm/fpu-internal.h | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 4bec98f..c615ae9 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -464,7 +464,9 @@ static inline int restore_xstate_sig(void __user *buf, int ia32_frame) * Need to be preemption-safe. * * NOTE! user_fpu_begin() must be used only immediately before restoring - * it. This function does not do any save/restore on their own. + * it. This function does not do any save/restore on its own. In a lazy + * fpu mode this is just optimization to avoid a dna fault, the task can + * lose FPU right after preempt_enable(). */ static inline void user_fpu_begin(void) { -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
