Subject: Re: [tip:sched/core] sched, tile: Remove finish_arch_switch
To: <linux-kernel@vger.kernel.org>, <hpa@zytor.com>, <mingo@kernel.org>,
        <torvalds@linux-foundation.org>, <tglx@linutronix.de>, <efault@gmx.de>,
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References: <tip-fe363adb922583bacfbd5a30a4c773ccff9bb393@git.kernel.org>
From: Chris Metcalf <cmetcalf@ezchip.com>
Message-ID: <55C0C23D.7020501@ezchip.com>
Date: Tue, 4 Aug 2015 09:46:37 -0400
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Ingo,

I already have the appended commit in a modified form in the linux-tile
tree ready to be pushed to 4.3.  Can you drop it from your series?

Thanks!

On 8/4/2015 4:50 AM, tip-bot for Chris Metcalf wrote:
> Commit-ID:  fe363adb922583bacfbd5a30a4c773ccff9bb393
> Gitweb:     http://git.kernel.org/tip/fe363adb922583bacfbd5a30a4c773ccff9bb393
> Author:     Chris Metcalf <cmetcalf@ezchip.com>
> AuthorDate: Wed, 29 Jul 2015 13:06:29 -0400
> Committer:  Ingo Molnar <mingo@kernel.org>
> CommitDate: Tue, 4 Aug 2015 09:38:18 +0200
>
> sched, tile: Remove finish_arch_switch
>
> Move the simulator bits into switch_to() and use
> finish_arch_post_lock_switch() for the homecache migration bits.
>
> Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
>   arch/tile/include/asm/switch_to.h | 10 +++-------
>   arch/tile/kernel/process.c        | 17 +++++++++++++++--
>   2 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/arch/tile/include/asm/switch_to.h b/arch/tile/include/asm/switch_to.h
> index b8f888c..422842a 100644
> --- a/arch/tile/include/asm/switch_to.h
> +++ b/arch/tile/include/asm/switch_to.h
> @@ -53,15 +53,11 @@ extern unsigned long get_switch_to_pc(void);
>    * Kernel threads can check to see if they need to migrate their
>    * stack whenever they return from a context switch; for user
>    * threads, we defer until they are returning to user-space.
> + * We defer homecache migration until the runqueue lock is released.
>    */
> -#define finish_arch_switch(prev) do {                                     \
> -	if (unlikely((prev)->state == TASK_DEAD))                         \
> -		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
> -			((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
> -	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
> -		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
> +#define finish_arch_post_lock_switch() do {                               \
>   	if (current->mm == NULL && !kstack_hash &&                        \
> -	    current_thread_info()->homecache_cpu != smp_processor_id())   \
> +	    current_thread_info()->homecache_cpu != raw_smp_processor_id()) \
>   		homecache_migrate_kthread();                              \
>   } while (0)
>   
> diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
> index a452137..1087375 100644
> --- a/arch/tile/kernel/process.c
> +++ b/arch/tile/kernel/process.c
> @@ -448,11 +448,24 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
>   
>   	/*
>   	 * Switch kernel SP, PC, and callee-saved registers.
> +	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
> +	 * Once we return from this function we will have changed stacks
> +	 * and be running with current == next.
> +	 */
> +	__switch_to(prev, next, next_current_ksp0(next));
> +
> +	/* Notify the simulator of task switch and task exit. */
> +	if (unlikely(prev->state == TASK_DEAD))
> +		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
> +			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));
> +	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |
> +		(next->pid << _SIM_CONTROL_OPERATOR_BITS));
> +
> +	/*
>   	 * In the context of the new task, return the old task pointer
>   	 * (i.e. the task that actually called __switch_to).
> -	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
>   	 */
> -	return __switch_to(prev, next, next_current_ksp0(next));
> +	return prev;
>   }
>   
>   /*

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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