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Commit d647b36a authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
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[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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2caf62f6

include/net/snmp.h

+17 −4
Original line number Diff line number Diff line
@@ -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 @@ struct linux_mib { 
#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