[SNMP]: Fix SNMP counters with PREEMPT
The SNMP macros use raw_smp_processor_id() in process context
which is illegal because the process may be preempted and then
migrated to another CPU.
This patch makes it use get_cpu/put_cpu to disable preemption.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/snmp.h b/include/net/snmp.h
index 9c5793d..fbb6666 100644
--- a/include/net/snmp.h
+++ b/include/net/snmp.h
@@ -23,6 +23,7 @@
#include <linux/cache.h>
#include <linux/snmp.h>
+#include <linux/smp.h>
/*
* Mibs are stored in array of unsigned long.
@@ -135,14 +136,26 @@
#define SNMP_INC_STATS_BH(mib, field) \
(per_cpu_ptr(mib[0], raw_smp_processor_id())->mibs[field]++)
#define SNMP_INC_STATS_USER(mib, field) \
- (per_cpu_ptr(mib[1], raw_smp_processor_id())->mibs[field]++)
+ do { \
+ per_cpu_ptr(mib[1], get_cpu())->mibs[field]++; \
+ put_cpu(); \
+ } while (0)
#define SNMP_INC_STATS(mib, field) \
- (per_cpu_ptr(mib[!in_softirq()], raw_smp_processor_id())->mibs[field]++)
+ do { \
+ per_cpu_ptr(mib[!in_softirq()], get_cpu())->mibs[field]++; \
+ put_cpu(); \
+ } while (0)
#define SNMP_DEC_STATS(mib, field) \
- (per_cpu_ptr(mib[!in_softirq()], raw_smp_processor_id())->mibs[field]--)
+ do { \
+ per_cpu_ptr(mib[!in_softirq()], get_cpu())->mibs[field]--; \
+ put_cpu(); \
+ } while (0)
#define SNMP_ADD_STATS_BH(mib, field, addend) \
(per_cpu_ptr(mib[0], raw_smp_processor_id())->mibs[field] += addend)
#define SNMP_ADD_STATS_USER(mib, field, addend) \
- (per_cpu_ptr(mib[1], raw_smp_processor_id())->mibs[field] += addend)
+ do { \
+ per_cpu_ptr(mib[1], get_cpu())->mibs[field] += addend; \
+ put_cpu(); \
+ } while (0)
#endif