net: core: use this_cpu_ptr per-cpu helper

PATCH Superseded Shan Wei 3 participants 3 messages Nov 2, 2012 – Nov 3, 2012

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Shan Wei

author

2012-11-02 16:01 UTC #0 lore raw

PATCH v2 1/9 net: core: use this_cpu_ptr per-cpu helper

From: Shan Wei <[email protected]>

Signed-off-by Shan Wei <[email protected]>

Reviewed-by Christoph Lameter <[email protected]>

---
 net/core/flow.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

net/core/flow.c +1 -3

index e318c7e..3bad824 100644
@@ -327,11 +327,9 @@ static void flow_cache_flush_tasklet(unsigned long data)
 static void flow_cache_flush_per_cpu(void *data)
 {
 	struct flow_flush_info *info = data;
-	int cpu;
 	struct tasklet_struct *tasklet;
 
-	cpu = smp_processor_id();
-	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
+	tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet;
 	tasklet->data = (unsigned long)info;
 	tasklet_schedule(tasklet);
 }

Signature · 1 line

1.7.1

Christoph Lameter

2012-11-02 17:44 UTC #1 lore raw

net/core/flow.c static void flow_cache_flush_tasklet(unsigned long data) · line 332

Quoted 11 lines · Shan Wei

+++ b/net/core/flow.c

net/core/flow.c +1 -3

@@ -327,11 +327,9 @@ static void flow_cache_flush_tasklet(unsigned long data)
 static void flow_cache_flush_per_cpu(void *data)
 {
 	struct flow_flush_info *info = data;
-	int cpu;
 	struct tasklet_struct *tasklet;
 
-	cpu = smp_processor_id();
-	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
+	tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet

Another case for the use of this_cpu_read

Steffen Klassert

2012-11-03 08:20 UTC #2 lore raw

Quoted 9 lines · Christoph Lameter

Quoted 8 lines · Shan Wei

+++ b/net/core/flow.c

net/core/flow.c +0 -1

@@ -327,11 +327,9 @@ static void flow_cache_flush_tasklet(unsigned long data)
 static void flow_cache_flush_per_cpu(void *data)
 {
 	struct flow_flush_info *info = data;
-	int cpu;
 	struct tasklet_struct *tasklet;

Quoted 5 lines

net/core/flow.c static void flow_cache_flush_tasklet(unsigned long data)
Quoted 3 lines
net/core/flow.c +1 -2
-	cpu = smp_processor_id();
-	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
+	tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet
Another case for the use of this_cpu_read

Actually, smp_processor_id() is used if either preemtion is off or in a thread that is bound to the current cpu. So all code that uses smp_processor_id() should be able to use __this_cpu_read instead of this_cpu_read.

In this case, flow_cache_flush_per_cpu() is called via smp_call_function(), so it is bound on the current cpu.