[PATCH 6/6] tick/common: optimize cpumask_equal() usage

Yury Norov
2024-05-13T22:02:00Z

Some functions in the file call cpumask_equal() with src1p == src2p.
We can obviously just skip comparison entirely in this case.

This patch fixes cpumask_equal invocations when boot-test or LTP detect
such condition.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
kernel/time/tick-common.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index d88b13076b79..b31fef292833 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -253,7 +253,8 @@ static void tick_setup_device(struct tick_device *td,
* When the device is not per cpu, pin the interrupt to the
* current cpu:
*/
- if (!cpumask_equal(newdev->cpumask, cpumask))
+ if (newdev->cpumask != cpumask &&
+ !cpumask_equal(newdev->cpumask, cpumask))
irq_set_affinity(newdev->irq, cpumask);

/*
@@ -288,14 +289,19 @@ static bool tick_check_percpu(struct clock_event_device *curdev,
{
if (!cpumask_test_cpu(cpu, newdev->cpumask))
return false;
- if (cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
+ if (newdev->cpumask == cpumask_of(cpu) ||
+ cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
return true;
/* Check if irq affinity can be set */
if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq))
return false;
/* Prefer an existing cpu local device */
- if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
+ if (!curdev)
+ return true;
+ if (curdev->cpumask == cpumask_of(cpu) ||
+ cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
return false;
+
return true;
}

@@ -316,7 +322,8 @@ static bool tick_check_preferred(struct clock_event_device *curdev,
*/
return !curdev ||
newdev->rating > curdev->rating ||
- !cpumask_equal(curdev->cpumask, newdev->cpumask);
+ !(curdev->cpumask == newdev->cpumask &&
+ cpumask_equal(curdev->cpumask, newdev->cpumask));
}

/*
--
2.40.1