path: root/security
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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-19 18:59:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-19 18:59:47 -0700
commit044aea9b83614948c98564000db07d1d32b2d29b (patch)
treeb1f13ed2f4bb0bd40f7915a89aafaf449b6145cd /security
parent39ab05c8e0b519ff0a04a869f065746e6e8c3d95 (diff)
selinux: de-crapify avc cache stat code generation
You can turn off the avc cache stats, but distributions seem to not do that (perhaps because several performance tuning how-to's talk about the avc cache statistics). Which is sad, because the code it generates is truly horrendous, with the statistics update being sandwitched between get_cpu/put_cpu which in turn causes preemption disables etc. We're talking ten+ instructions just to increment a per-cpu variable in some pretty hot code. Fix the craziness by just using 'this_cpu_inc()' instead. Suddenly we only need a single 'inc' instruction to increment the statistics. This is quite noticeable in the incredibly hot avc_has_perm_noaudit() function (which triggers all the statistics by virtue of doing an avc_lookup() call). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
1 files changed, 1 insertions, 5 deletions
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 1d027e29ce8..5971e30e823 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -38,11 +38,7 @@
-#define avc_cache_stats_incr(field) \
-do { \
- per_cpu(avc_cache_stats, get_cpu()).field++; \
- put_cpu(); \
-} while (0)
+#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
#define avc_cache_stats_incr(field) do {} while (0)