[ 14/18] timer: Fix jiffies wrap behavior of round_jiffies_common()

From: Greg Kroah-Hartman
Date: Thu Jul 18 2013 - 22:33:30 EST


3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@xxxxxxxxx>

commit 9e04d3804d3ac97d8c03a41d78d0f0674b5d01e1 upstream.

Direct compare of jiffies related values does not work in the wrap
around case. Replace it with time_is_after_jiffies().

Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/519BC066.5080600@xxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/timer.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -145,9 +145,11 @@ static unsigned long round_jiffies_commo
/* now that we have rounded, subtract the extra skew again */
j -= cpu * 3;

- if (j <= jiffies) /* rounding ate our timeout entirely; */
- return original;
- return j;
+ /*
+ * Make sure j is still in the future. Otherwise return the
+ * unmodified value.
+ */
+ return time_is_after_jiffies(j) ? j : original;
}

/**


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/