Re: [PATCH v5 4/8] x86/mm/tlb: Flush remote and local TLBs concurrently

[Peter Zijlstra]

On Tue, Feb 09, 2021 at 02:16:49PM -0800, Nadav Amit wrote:
> @@ -816,8 +821,8 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
>  	 * doing a speculative memory access.
>  	 */
>  	if (info->freed_tables) {
> -		smp_call_function_many(cpumask, flush_tlb_func,
> -			       (void *)info, 1);
> +		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
> +				      cpumask);
>  	} else {
>  		/*
>  		 * Although we could have used on_each_cpu_cond_mask(),
> @@ -844,14 +849,15 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
>  			if (tlb_is_not_lazy(cpu))
>  				__cpumask_set_cpu(cpu, cond_cpumask);
>  		}
> -		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
> +		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
> +				      cpumask);
>  	}
>  }

Surely on_each_cpu_mask() is more appropriate? There the compiler can do
the NULL propagation because it's on the same TU.

--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -821,8 +821,7 @@ STATIC_NOPV void native_flush_tlb_multi(
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables) {
-		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
-				      cpumask);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	} else {
 		/*
 		 * Although we could have used on_each_cpu_cond_mask(),
@@ -849,8 +848,7 @@ STATIC_NOPV void native_flush_tlb_multi(
 			if (tlb_is_not_lazy(cpu))
 				__cpumask_set_cpu(cpu, cond_cpumask);
 		}
-		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
-				      cpumask);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	}
 }