linux-kernel - [PATCH] Fix bacct_add_tsk()'s use of do

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Date:	Fri, 11 Jul 2008 14:28:13 +0100
From:	David Howells <dhowells@...hat.com>
To:	jlan@....com, akpm@...ux-foundation.org
Cc:	dhowells@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH] Fix bacct_add_tsk()'s use of do_div()

Fix bacct_add_tsk()'s use of do_div() on an s64 by making ac_etime a u64
instead and dividing that.

Possibly this should be guarded lest the interval calculation turn up negative,
but the possible negativity of the result of the division is cast away, and it
shouldn't end up negative anyway.

This was introduced by patch f3cef7a99469afc159fec3a61b42dc7ca5b6824f.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 kernel/tsacct.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)


diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index 4ab1b58..30e877f 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -28,14 +28,14 @@
 void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
 {
 	struct timespec uptime, ts;
-	s64 ac_etime;
+	u64 ac_etime;
 
 	BUILD_BUG_ON(TS_COMM_LEN < TASK_COMM_LEN);
 
 	/* calculate task elapsed time in timespec */
 	do_posix_clock_monotonic_gettime(&uptime);
 	ts = timespec_sub(uptime, tsk->start_time);
-	/* rebase elapsed time to usec */
+	/* rebase elapsed time to usec (should never be negative) */
 	ac_etime = timespec_to_ns(&ts);
 	do_div(ac_etime, NSEC_PER_USEC);
 	stats->ac_etime = ac_etime;

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