linux-kernel - [RFC PATCH 03/10] timer: Simplify LVL_START() and calc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200701011030.14324-4-frederic@kernel.org>
Date:   Wed,  1 Jul 2020 03:10:23 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>
Subject: [RFC PATCH 03/10] timer: Simplify LVL_START() and calc_index()

LVL_START() makes the first index of a level to start with what would be
the value of all bits set of the previous level.

For example level 1 starts at 63 instead of 64.

To cope with that, calc_index() always adds one offset for the level
granularity to the expiry passed in parameter.

Yet there is no apparent reason for such fixups so simplify the whole
thing.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Anna-Maria Gleixner <anna-maria@...utronix.de>
Cc: Juri Lelli <juri.lelli@...hat.com>
---
 kernel/time/timer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 4c977df3610b..b4838d63a016 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -158,7 +158,7 @@ EXPORT_SYMBOL(jiffies_64);
  * The time start value for each level to select the bucket at enqueue
  * time.
  */
-#define LVL_START(n)	((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT))
+#define LVL_START(n)	(LVL_SIZE << (((n) - 1) * LVL_CLK_SHIFT))
 
 /* Size of each clock level */
 #define LVL_BITS	6
@@ -489,7 +489,7 @@ static inline void timer_set_idx(struct timer_list *timer, unsigned int idx)
  */
 static inline unsigned calc_index(unsigned expires, unsigned lvl)
 {
-	expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl);
+	expires >>= LVL_SHIFT(lvl);
 	return LVL_OFFS(lvl) + (expires & LVL_MASK);
 }
 
-- 
2.26.2