diff options
| author | Phil Carmody <ext-phil.2.carmody@nokia.com> | 2010-05-26 14:42:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 09:12:43 -0700 |
| commit | 5407a56257b6ade44fd9bcac972c99845b7413cd (patch) | |
| tree | 833a55856af25fe9be5e8a871d89f43677eac512 /mm/memcontrol.c | |
| parent | df64f81bb1e01cbef967a96642dacf208acb7e72 (diff) | |
| download | lwn-5407a56257b6ade44fd9bcac972c99845b7413cd.tar.gz lwn-5407a56257b6ade44fd9bcac972c99845b7413cd.zip | |
mm: remove unnecessary use of atomic
The bottom 4 hunks are atomically changing memory to which there are no
aliases as it's freshly allocated, so there's no need to use atomic
operations.
The other hunks are just atomic_read and atomic_set, and do not involve
any read-modify-write. The use of atomic_{read,set} doesn't prevent a
read/write or write/write race, so if a race were possible (I'm not saying
one is), then it would still be there even with atomic_set.
See:
http://digitalvampire.org/blog/index.php/2007/05/13/atomic-cargo-cults/
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index be5f478351bd..93b0239bc34d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -152,7 +152,7 @@ struct mem_cgroup_threshold { /* For threshold */ struct mem_cgroup_threshold_ary { /* An array index points to threshold just below usage. */ - atomic_t current_threshold; + int current_threshold; /* Size of entries[] */ unsigned int size; /* Array of thresholds */ @@ -3412,7 +3412,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) * If it's not true, a threshold was crossed after last * call of __mem_cgroup_threshold(). */ - i = atomic_read(&t->current_threshold); + i = t->current_threshold; /* * Iterate backward over array of thresholds starting from @@ -3436,7 +3436,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) eventfd_signal(t->entries[i].eventfd, 1); /* Update current_threshold */ - atomic_set(&t->current_threshold, i - 1); + t->current_threshold = i - 1; unlock: rcu_read_unlock(); } @@ -3528,7 +3528,7 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp, compare_thresholds, NULL); /* Find current threshold */ - atomic_set(&thresholds_new->current_threshold, -1); + thresholds_new->current_threshold = -1; for (i = 0; i < size; i++) { if (thresholds_new->entries[i].threshold < usage) { /* @@ -3536,7 +3536,7 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp, * until rcu_assign_pointer(), so it's safe to increment * it here. */ - atomic_inc(&thresholds_new->current_threshold); + ++thresholds_new->current_threshold; } } @@ -3607,7 +3607,7 @@ static int mem_cgroup_usage_unregister_event(struct cgroup *cgrp, thresholds_new->size = size; /* Copy thresholds and find current threshold */ - atomic_set(&thresholds_new->current_threshold, -1); + thresholds_new->current_threshold = -1; for (i = 0, j = 0; i < thresholds->size; i++) { if (thresholds->entries[i].eventfd == eventfd) continue; @@ -3619,7 +3619,7 @@ static int mem_cgroup_usage_unregister_event(struct cgroup *cgrp, * until rcu_assign_pointer(), so it's safe to increment * it here. */ - atomic_inc(&thresholds_new->current_threshold); + ++thresholds_new->current_threshold; } j++; } |