On Wed, Nov 13, 2013 at 09:16:13AM +0100, Martin Schwidefsky wrote:
> The switch_mm function is called with the task_lock and/or with
> request queue lock. Add finish_switch_mm to allow an architecture
> to execute some code after the mm has been switched but without
> any locks held. One use case is the s390 architecture which will
> use this to wait for the completion of TLB flush operations.
This so reminds me of what finish_arch_post_lock_switch() was supposed
to do. See commit: 01f23e1630d9 ("sched/arch: Introduce the
finish_arch_post_lock_switch() scheduler callback").
Now you hook into more places; but maybe you can Catalin can come up
with something you both can use?
(preserved patch for Catalin)
> Signed-off-by: Martin Schwidefsky <schwidef...@de.ibm.com>
> ---
> include/linux/mmu_context.h | 6 ++++++
> kernel/sched/core.c | 7 +++++--
> mm/mmu_context.c | 3 +--
> 3 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h
> index 70fffeb..0971c37 100644
> --- a/include/linux/mmu_context.h
> +++ b/include/linux/mmu_context.h
> @@ -1,9 +1,15 @@
> #ifndef _LINUX_MMU_CONTEXT_H
> #define _LINUX_MMU_CONTEXT_H
>
> +#include <asm/mmu_context.h>
> +
> struct mm_struct;
>
> void use_mm(struct mm_struct *mm);
> void unuse_mm(struct mm_struct *mm);
>
> +#ifndef finish_switch_mm
> +#define finish_switch_mm(mm, tsk) do { } while (0)
> +#endif
> +
> #endif
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 1deccd7..89409cb 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -32,7 +32,7 @@
> #include <linux/init.h>
> #include <linux/uaccess.h>
> #include <linux/highmem.h>
> -#include <asm/mmu_context.h>
> +#include <linux/mmu_context.h>
> #include <linux/interrupt.h>
> #include <linux/capability.h>
> #include <linux/completion.h>
> @@ -1996,6 +1996,7 @@ static void finish_task_switch(struct rq *rq, struct
> task_struct *prev)
> perf_event_task_sched_in(prev, current);
> finish_lock_switch(rq, prev);
> finish_arch_post_lock_switch();
> + finish_switch_mm(current->mm, current);
>
> fire_sched_in_preempt_notifiers(current);
> if (mm)
> @@ -4140,8 +4141,10 @@ void idle_task_exit(void)
>
> BUG_ON(cpu_online(smp_processor_id()));
>
> - if (mm != &init_mm)
> + if (mm != &init_mm) {
> switch_mm(mm, &init_mm, current);
> + finish_switch_mm(&init_mm, current);
> + }
> mmdrop(mm);
> }
>
> diff --git a/mm/mmu_context.c b/mm/mmu_context.c
> index 8a8cd02..11b3d47 100644
> --- a/mm/mmu_context.c
> +++ b/mm/mmu_context.c
> @@ -8,8 +8,6 @@
> #include <linux/export.h>
> #include <linux/sched.h>
>
> -#include <asm/mmu_context.h>
> -
> /*
> * use_mm
> * Makes the calling kernel thread take on the specified
> @@ -31,6 +29,7 @@ void use_mm(struct mm_struct *mm)
> tsk->mm = mm;
> switch_mm(active_mm, mm, tsk);
> task_unlock(tsk);
> + finish_switch_mm(mm, tsk);
>
> if (active_mm != mm)
> mmdrop(active_mm);
> --
> 1.7.9.5
>
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