[PATCH 1/7] x86: mm: clean up tlb flushing code

From: Dave Hansen
Date: Thu Jul 31 2014 - 11:41:00 EST



From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

The

if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)

line of code is not exactly the easiest to audit, especially when
it ends up at two different indentation levels. This eliminates
one of the the copy-n-paste versions. It also gives us a unified
exit point for each path through this function. We need this in
a minute for our tracepoint.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
---

b/arch/x86/mm/tlb.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)

diff -puN arch/x86/mm/tlb.c~simplify-tlb-code arch/x86/mm/tlb.c
--- a/arch/x86/mm/tlb.c~simplify-tlb-code 2014-06-30 16:18:05.525535882 -0700
+++ b/arch/x86/mm/tlb.c 2014-06-30 16:18:05.535536335 -0700
@@ -161,23 +161,24 @@ void flush_tlb_current_task(void)
void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long vmflag)
{
+ bool need_flush_others_all = true;
unsigned long addr;
unsigned act_entries, tlb_entries = 0;
unsigned long nr_base_pages;

preempt_disable();
if (current->active_mm != mm)
- goto flush_all;
+ goto out;

if (!current->mm) {
leave_mm(smp_processor_id());
- goto flush_all;
+ goto out;
}

if (end == TLB_FLUSH_ALL || tlb_flushall_shift == -1
|| vmflag & VM_HUGETLB) {
local_flush_tlb();
- goto flush_all;
+ goto out;
}

/* In modern CPU, last level tlb used for both data/ins */
@@ -196,22 +197,20 @@ void flush_tlb_mm_range(struct mm_struct
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
local_flush_tlb();
} else {
+ need_flush_others_all = false;
/* flush range by one by one 'invlpg' */
for (addr = start; addr < end; addr += PAGE_SIZE) {
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
__flush_tlb_single(addr);
}
-
- if (cpumask_any_but(mm_cpumask(mm),
- smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, start, end);
- preempt_enable();
- return;
}
-
-flush_all:
+out:
+ if (need_flush_others_all) {
+ start = 0UL;
+ end = TLB_FLUSH_ALL;
+ }
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, 0UL, TLB_FLUSH_ALL);
+ flush_tlb_others(mm_cpumask(mm), mm, start, end);
preempt_enable();
}

_
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