latencytop: fix per task accumulator

Per task latencytop accumulator prematurely terminates due to erroneous
placement of latency_record_count.  It should be incremented whenever a
new record is allocated instead of increment on every latencytop event.

Also fix search iterator to only search known record events instead of
blindly searching all pre-allocated space.

Signed-off-by: Ken Chen <kenchen@google.com>
Reviewed-by: Arjan van de Ven <arjan@infradead.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 9 deletions

diff --git a/kernel/latencytop.c b/kernel/latencytop.c
index 877fb306d415..17110a4a4fc2 100644
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -194,14 +194,7 @@ __account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
 
         account_global_scheduler_latency(tsk, &lat);
 
-        /*
-         * short term hack; if we're > 32 we stop; future we recycle:
-         */
-        tsk->latency_record_count++;
-        if (tsk->latency_record_count >= LT_SAVECOUNT)
-                goto out_unlock;
-
-        for (i = 0; i < LT_SAVECOUNT; i++) {
+        for (i = 0; i < tsk->latency_record_count; i++) {
                 struct latency_record *mylat;
                 int same = 1;
 
@@ -227,8 +220,14 @@ __account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
                 }
         }
 
+        /*
+         * short term hack; if we're > 32 we stop; future we recycle:
+         */
+        if (tsk->latency_record_count >= LT_SAVECOUNT)
+                goto out_unlock;
+
         /* Allocated a new one: */
-        i = tsk->latency_record_count;
+        i = tsk->latency_record_count++;
         memcpy(&tsk->latency_record[i], &lat, sizeof(struct latency_record));
 
 out_unlock: