On Tue, Mar 07, 2006 at 06:13:01PM -0800, Andrew Morton wrote:
> Ravikiran G Thirumalai <[email protected]> wrote:
> >
> > +static inline void percpu_counter_mod_bh(struct percpu_counter *fbc, long amount)
> > +{
> > + local_bh_disable();
> > + percpu_counter_mod(fbc, amount);
> > + local_bh_enable();
> > +}
> > +
>
> percpu_counter_mod() does preempt_disable(), which is redundant in this
> context. So just do fbc->count += amount; here.
OK. Here is the revised patch.
Add percpu_counter_mod_bh for using these counters safely from
both softirq and process context.
Signed-off by: Pravin B. Shelar <[email protected]>
Signed-off by: Ravikiran G Thirumalai <[email protected]>
Signed-off by: Shai Fultheim <[email protected]>
Index: linux-2.6.16-rc5mm3/include/linux/percpu_counter.h
===================================================================
--- linux-2.6.16-rc5mm3.orig/include/linux/percpu_counter.h 2006-03-07 15:08:00.000000000 -0800
+++ linux-2.6.16-rc5mm3/include/linux/percpu_counter.h 2006-03-08 10:53:13.000000000 -0800
@@ -11,6 +11,7 @@
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/percpu.h>
+#include <linux/interrupt.h>
#ifdef CONFIG_SMP
@@ -40,6 +41,7 @@ static inline void percpu_counter_destro
void percpu_counter_mod(struct percpu_counter *fbc, long amount);
long percpu_counter_sum(struct percpu_counter *fbc);
+void percpu_counter_mod_bh(struct percpu_counter *fbc, long amount);
static inline long percpu_counter_read(struct percpu_counter *fbc)
{
@@ -98,6 +100,12 @@ static inline long percpu_counter_sum(st
return percpu_counter_read_positive(fbc);
}
+static inline void percpu_counter_mod_bh(struct percpu_counter *fbc, long amount)
+{
+ local_bh_disable();
+ fbc->count += amount;
+ local_bh_enable();
+}
#endif /* CONFIG_SMP */
static inline void percpu_counter_inc(struct percpu_counter *fbc)
@@ -110,4 +118,5 @@ static inline void percpu_counter_dec(st
percpu_counter_mod(fbc, -1);
}
+
#endif /* _LINUX_PERCPU_COUNTER_H */
Index: linux-2.6.16-rc5mm3/mm/swap.c
===================================================================
--- linux-2.6.16-rc5mm3.orig/mm/swap.c 2006-03-07 15:08:01.000000000 -0800
+++ linux-2.6.16-rc5mm3/mm/swap.c 2006-03-08 12:11:19.000000000 -0800
@@ -521,11 +521,11 @@ static int cpu_swap_callback(struct noti
#endif /* CONFIG_SMP */
#ifdef CONFIG_SMP
-void percpu_counter_mod(struct percpu_counter *fbc, long amount)
+static void __percpu_counter_mod(struct percpu_counter *fbc, long amount)
{
long count;
long *pcount;
- int cpu = get_cpu();
+ int cpu = smp_processor_id();
pcount = per_cpu_ptr(fbc->counters, cpu);
count = *pcount + amount;
@@ -537,9 +537,21 @@ void percpu_counter_mod(struct percpu_co
} else {
*pcount = count;
}
- put_cpu();
}
-EXPORT_SYMBOL(percpu_counter_mod);
+
+void percpu_counter_mod(struct percpu_counter *fbc, long amount)
+{
+ preempt_disable();
+ __percpu_counter_mod(fbc, amount);
+ preempt_enable();
+}
+
+void percpu_counter_mod_bh(struct percpu_counter *fbc, long amount)
+{
+ local_bh_disable();
+ __percpu_counter_mod(fbc, amount);
+ local_bh_enable();
+}
/*
* Add up all the per-cpu counts, return the result. This is a more accurate
@@ -559,6 +571,9 @@ long percpu_counter_sum(struct percpu_co
spin_unlock(&fbc->lock);
return ret < 0 ? 0 : ret;
}
+
+EXPORT_SYMBOL(percpu_counter_mod);
+EXPORT_SYMBOL(percpu_counter_mod_bh);
EXPORT_SYMBOL(percpu_counter_sum);
#endif
-
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