[RFC PATCH 03/10] timer: Simplify LVL_START() and calc_index()

Frederic Weisbecker
2020-07-01T01:11:15Z

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@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.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