Herbert Xu a écrit :
Ob Tue, Dec 04, 2007 at 12:17:23AM +1100, Herbert Xu wrote:
Never mind, we already have that in local_t and as Alexey correctly
points out, USER is still going to be the expensive variant with the
preempt_disable (well until BH gets threaded). So how about this patch?
I didn't hear any objections so here is the patch again.
[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 <[email protected]>
Cheers,
#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]++)
How come you change SNMP_INC_STATS_USER() but not SNMP_INC_STATS() ?
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