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SubjectRe: [rfc patch v4.4-rt2] sched: fix up preempt lazy forward port
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On 01/22/2016 10:40 PM, Sebastian Andrzej Siewior wrote:
> * Sebastian Andrzej Siewior | 2016-01-22 13:54:43 [+0100]:
>
>>> Should _TIF_WORK_MASK also contain _TIF_NEED_RESCHED_LAZY?
>>
>> Yes, and arm64 lacks the same bits.
>
> That would be this. If a compiler is reading here and knows how to
> improve the following, please let me know :)
>
> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
> index 46cc07b5cae6..1f36a4eccc72 100644
> --- a/arch/arm/include/asm/thread_info.h
> +++ b/arch/arm/include/asm/thread_info.h
> @@ -143,8 +143,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
> #define TIF_SYSCALL_TRACE 4 /* syscall trace active */
> #define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
> #define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
> -#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
> -#define TIF_NEED_RESCHED_LAZY 8
> +#define TIF_SECCOMP 8 /* seccomp syscall filtering active */
> +#define TIF_NEED_RESCHED_LAZY 7
>
> #define TIF_NOHZ 12 /* in adaptive nohz mode */
> #define TIF_USING_IWMMXT 17
> @@ -170,7 +170,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
> * Change these and you break ASM code in entry-common.S
> */
> #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
> - _TIF_NOTIFY_RESUME | _TIF_UPROBE)
> + _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
> + _TIF_NEED_RESCHED_LAZY)
>
> #endif /* __KERNEL__ */
> #endif /* __ASM_ARM_THREAD_INFO_H */
> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
> index 30a7228eaceb..c3bd6cbfce4b 100644
> --- a/arch/arm/kernel/entry-common.S
> +++ b/arch/arm/kernel/entry-common.S
> @@ -36,7 +36,9 @@
> UNWIND(.cantunwind )
> disable_irq_notrace @ disable interrupts
> ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
> - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
> + tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP)
> + bne fast_work_pending
^^^^^^^^^^^^^^^^

> + tst r1, #_TIF_SECCOMP
> bne fast_work_pending
^^^^^^^^^^^^^^^^^

Should it be "fast_work_pending" in both cases?

>
> /* perform architecture specific actions before user return */
> @@ -62,8 +64,11 @@ ENDPROC(ret_fast_syscall)
> str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
> disable_irq_notrace @ disable interrupts
> ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
> - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
> + tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP)
> + bne do_slower_path
> + tst r1, #_TIF_SECCOMP
> beq no_work_pending
> +do_slower_path:
> UNWIND(.fnend )
> ENDPROC(ret_fast_syscall)
>
[...]

--
regards,
-grygorii

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