linux-kernel - [tip: timers/core] timers: Preserve higher bits of expiration on index calculation

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Date:   Fri, 17 Jul 2020 20:00:21 -0000
From:   "tip-bot2 for Frederic Weisbecker" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: timers/core] timers: Preserve higher bits of expiration on
 index calculation

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     3d2e83a2a6a0657c1cf145fa6ba23620715d6c36
Gitweb:        https://git.kernel.org/tip/3d2e83a2a6a0657c1cf145fa6ba23620715d6c36
Author:        Frederic Weisbecker <frederic@...nel.org>
AuthorDate:    Fri, 17 Jul 2020 16:05:41 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Fri, 17 Jul 2020 21:55:21 +02:00

timers: Preserve higher bits of expiration on index calculation

The higher bits of the timer expiration are cropped while calling
calc_index() due to the implicit cast from unsigned long to unsigned int.

This loss shouldn't have consequences on the current code since all the
computation to calculate the index is done on the lower 32 bits.

However to prepare for returning the actual bucket expiration from
calc_index() in order to properly fix base->next_expiry updates, the higher
bits need to be preserved.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20200717140551.29076-3-frederic@kernel.org

---
 kernel/time/timer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index df1ff80..bcdc304 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -487,7 +487,7 @@ static inline void timer_set_idx(struct timer_list *timer, unsigned int idx)
  * Helper function to calculate the array index for a given expiry
  * time.
  */
-static inline unsigned calc_index(unsigned expires, unsigned lvl)
+static inline unsigned calc_index(unsigned long expires, unsigned lvl)
 {
 	expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl);
 	return LVL_OFFS(lvl) + (expires & LVL_MASK);