FROMLIST: binder: change binder_stats to atomics

(from https://patchwork.kernel.org/patch/9817755/)

Use atomics for stats to avoid needing to lock for
increments/decrements

Bug: 33250092 32225111
Change-Id: I13e69b7f0485ccf16673e25091455781e1933a98
Signed-off-by: Todd Kjos <tkjos@google.com>

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 9c65594907ca374b42fdd1b519b07bb251195ceb..6d7b0a78de03110acd489a9173abd83b3c20ed45 100644 (file)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -167,22 +167,22 @@ enum binder_stat_types {
 };
 
 struct binder_stats {
-       int br[_IOC_NR(BR_FAILED_REPLY) + 1];
-       int bc[_IOC_NR(BC_REPLY_SG) + 1];
-       int obj_created[BINDER_STAT_COUNT];
-       int obj_deleted[BINDER_STAT_COUNT];
+       atomic_t br[_IOC_NR(BR_FAILED_REPLY) + 1];
+       atomic_t bc[_IOC_NR(BC_REPLY_SG) + 1];
+       atomic_t obj_created[BINDER_STAT_COUNT];
+       atomic_t obj_deleted[BINDER_STAT_COUNT];
 };
 
 static struct binder_stats binder_stats;
 
 static inline void binder_stats_deleted(enum binder_stat_types type)
 {
-       binder_stats.obj_deleted[type]++;
+       atomic_inc(&binder_stats.obj_deleted[type]);
 }
 
 static inline void binder_stats_created(enum binder_stat_types type)
 {
-       binder_stats.obj_created[type]++;
+       atomic_inc(&binder_stats.obj_created[type]);
 }
 
 struct binder_transaction_log_entry {
@@ -1826,9 +1826,9 @@ int binder_thread_write(struct binder_proc *proc,
                ptr += sizeof(uint32_t);
                trace_binder_command(cmd);
                if (_IOC_NR(cmd) < ARRAY_SIZE(binder_stats.bc)) {
-                       binder_stats.bc[_IOC_NR(cmd)]++;
-                       proc->stats.bc[_IOC_NR(cmd)]++;
-                       thread->stats.bc[_IOC_NR(cmd)]++;
+                       atomic_inc(&binder_stats.bc[_IOC_NR(cmd)]);
+                       atomic_inc(&proc->stats.bc[_IOC_NR(cmd)]);
+                       atomic_inc(&thread->stats.bc[_IOC_NR(cmd)]);
                }
                switch (cmd) {
                case BC_INCREFS:
@@ -2202,9 +2202,9 @@ static void binder_stat_br(struct binder_proc *proc,
 {
        trace_binder_return(cmd);
        if (_IOC_NR(cmd) < ARRAY_SIZE(binder_stats.br)) {
-               binder_stats.br[_IOC_NR(cmd)]++;
-               proc->stats.br[_IOC_NR(cmd)]++;
-               thread->stats.br[_IOC_NR(cmd)]++;
+               atomic_inc(&binder_stats.br[_IOC_NR(cmd)]);
+               atomic_inc(&proc->stats.br[_IOC_NR(cmd)]);
+               atomic_inc(&thread->stats.br[_IOC_NR(cmd)]);
        }
 }
 
@@ -3454,17 +3454,21 @@ static void print_binder_stats(struct seq_file *m, const char *prefix,
        BUILD_BUG_ON(ARRAY_SIZE(stats->bc) !=
                     ARRAY_SIZE(binder_command_strings));
        for (i = 0; i < ARRAY_SIZE(stats->bc); i++) {
-               if (stats->bc[i])
+               int temp = atomic_read(&stats->bc[i]);
+
+               if (temp)
                        seq_printf(m, "%s%s: %d\n", prefix,
-                                  binder_command_strings[i], stats->bc[i]);
+                                  binder_command_strings[i], temp);
        }
 
        BUILD_BUG_ON(ARRAY_SIZE(stats->br) !=
                     ARRAY_SIZE(binder_return_strings));
        for (i = 0; i < ARRAY_SIZE(stats->br); i++) {
-               if (stats->br[i])
+               int temp = atomic_read(&stats->br[i]);
+
+               if (temp)
                        seq_printf(m, "%s%s: %d\n", prefix,
-                                  binder_return_strings[i], stats->br[i]);
+                                  binder_return_strings[i], temp);
        }
 
        BUILD_BUG_ON(ARRAY_SIZE(stats->obj_created) !=
@@ -3472,11 +3476,15 @@ static void print_binder_stats(struct seq_file *m, const char *prefix,
        BUILD_BUG_ON(ARRAY_SIZE(stats->obj_created) !=
                     ARRAY_SIZE(stats->obj_deleted));
        for (i = 0; i < ARRAY_SIZE(stats->obj_created); i++) {
-               if (stats->obj_created[i] || stats->obj_deleted[i])
-                       seq_printf(m, "%s%s: active %d total %d\n", prefix,
+               int created = atomic_read(&stats->obj_created[i]);
+               int deleted = atomic_read(&stats->obj_deleted[i]);
+
+               if (created || deleted)
+                       seq_printf(m, "%s%s: active %d total %d\n",
+                               prefix,
                                binder_objstat_strings[i],
-                               stats->obj_created[i] - stats->obj_deleted[i],
-                               stats->obj_created[i]);
+                               created - deleted,
+                               created);
        }
 }