Subject: Re: [PATCH v2 2/3] powerpc/64s/radix: tlbie improve preempt handling

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Thu, 26 Oct 2017 12:23:33 +0530

Nicholas Piggin <[email-masked]> writes:

> Preempt should be consistently disabled for mm_is_thread_local tests,
> so bring the rest of these under preempt_disable().
>
> Preempt does not need to be disabled for the mm->context.id tests,
> which allows simplification and removal of gotos.
>

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

> Signed-off-by: Nicholas Piggin <[email-masked]>
> ---
>  arch/powerpc/mm/tlb-radix.c | 48 +++++++++++++++++++++------------------------
>  1 file changed, 22 insertions(+), 26 deletions(-)
>
> diff --git a/arch/powerpc/mm/tlb-radix.c b/arch/powerpc/mm/tlb-radix.c
> index 892544ebc2d2..18170dc264aa 100644
> --- a/arch/powerpc/mm/tlb-radix.c
> +++ b/arch/powerpc/mm/tlb-radix.c
> @@ -186,16 +186,15 @@ void radix__flush_tlb_mm(struct mm_struct *mm)
>  {
>  	unsigned long pid;
>
> -	preempt_disable();
>  	pid = mm->context.id;
>  	if (unlikely(pid == MMU_NO_CONTEXT))
> -		goto no_context;
> +		return;
>
> +	preempt_disable();
>  	if (!mm_is_thread_local(mm))
>  		_tlbie_pid(pid, RIC_FLUSH_TLB);
>  	else
>  		_tlbiel_pid(pid, RIC_FLUSH_TLB);
> -no_context:
>  	preempt_enable();
>  }
>  EXPORT_SYMBOL(radix__flush_tlb_mm);
> @@ -204,16 +203,15 @@ void radix__flush_all_mm(struct mm_struct *mm)
>  {
>  	unsigned long pid;
>
> -	preempt_disable();
>  	pid = mm->context.id;
>  	if (unlikely(pid == MMU_NO_CONTEXT))
> -		goto no_context;
> +		return;
>
> +	preempt_disable();
>  	if (!mm_is_thread_local(mm))
>  		_tlbie_pid(pid, RIC_FLUSH_ALL);
>  	else
>  		_tlbiel_pid(pid, RIC_FLUSH_ALL);
> -no_context:
>  	preempt_enable();
>  }
>  EXPORT_SYMBOL(radix__flush_all_mm);
> @@ -230,15 +228,14 @@ void radix__flush_tlb_page_psize(struct mm_struct *mm, unsigned long vmaddr,
>  	unsigned long pid;
>  	unsigned long ap = mmu_get_ap(psize);
>
> -	preempt_disable();
>  	pid = mm->context.id;
>  	if (unlikely(pid == MMU_NO_CONTEXT))
> -		goto bail;
> +		return;
> +	preempt_disable();
>  	if (!mm_is_thread_local(mm))
>  		_tlbie_va(vmaddr, pid, ap, RIC_FLUSH_TLB);
>  	else
>  		_tlbiel_va(vmaddr, pid, ap, RIC_FLUSH_TLB);
> -bail:
>  	preempt_enable();
>  }
>
> @@ -322,54 +319,53 @@ void radix__flush_tlb_range_psize(struct mm_struct *mm, unsigned long start,
>  {
>  	unsigned long pid;
>  	unsigned long addr;
> -	int local = mm_is_thread_local(mm);
> +	bool local;
>  	unsigned long ap = mmu_get_ap(psize);
>  	unsigned long page_size = 1UL << mmu_psize_defs[psize].shift;
>
> -
> -	preempt_disable();
>  	pid = mm->context.id;
>  	if (unlikely(pid == MMU_NO_CONTEXT))
> -		goto err_out;
> +		return;
>
> +	preempt_disable();
> +	local = mm_is_thread_local(mm);
>  	if (end == TLB_FLUSH_ALL ||
>  	    (end - start) > tlb_single_page_flush_ceiling * page_size) {
>  		if (local)
>  			_tlbiel_pid(pid, RIC_FLUSH_TLB);
>  		else
>  			_tlbie_pid(pid, RIC_FLUSH_TLB);
> -		goto err_out;
> -	}
> -	for (addr = start; addr < end; addr += page_size) {
> +	} else {
> +		for (addr = start; addr < end; addr += page_size) {
>
> -		if (local)
> -			_tlbiel_va(addr, pid, ap, RIC_FLUSH_TLB);
> -		else
> -			_tlbie_va(addr, pid, ap, RIC_FLUSH_TLB);
> +			if (local)
> +				_tlbiel_va(addr, pid, ap, RIC_FLUSH_TLB);
> +			else
> +				_tlbie_va(addr, pid, ap, RIC_FLUSH_TLB);
> +		}
>  	}
> -err_out:
>  	preempt_enable();
>  }
>
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  void radix__flush_tlb_collapsed_pmd(struct mm_struct *mm, unsigned long addr)
>  {
> -	int local = mm_is_thread_local(mm);
>  	unsigned long ap = mmu_get_ap(mmu_virtual_psize);
>  	unsigned long pid, end;
> +	bool local;
>
> -	preempt_disable();
>  	pid = mm->context.id;
>  	if (unlikely(pid == MMU_NO_CONTEXT))
> -		goto no_context;
> +		return;
>
>  	/* 4k page size, just blow the world */
>  	if (PAGE_SIZE == 0x1000) {
>  		radix__flush_all_mm(mm);
> -		preempt_enable();
>  		return;
>  	}
>
> +	preempt_disable();
> +	local = mm_is_thread_local(mm);
>  	/* Otherwise first do the PWC */
>  	if (local)
>  		_tlbiel_pid(pid, RIC_FLUSH_PWC);
> @@ -384,7 +380,7 @@ void radix__flush_tlb_collapsed_pmd(struct mm_struct *mm, unsigned long addr)
>  		else
>  			_tlbie_va(addr, pid, ap, RIC_FLUSH_TLB);
>  	}
> -no_context:
> +
>  	preempt_enable();
>  }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> -- 
> 2.13.3