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

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

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);
        }
 }