[tip: timers/core] hrtimer: Use raw_cpu_ptr() in clock_was_set()

From: tip-bot2 for Thomas Gleixner
Date: Thu Aug 12 2021 - 16:40:19 EST


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

Commit-ID: 9482fd71dbb8f0d1a61821a83e467dc0a9d7b429
Gitweb: https://git.kernel.org/tip/9482fd71dbb8f0d1a61821a83e467dc0a9d7b429
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 12 Aug 2021 22:31:24 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 12 Aug 2021 22:34:40 +02:00

hrtimer: Use raw_cpu_ptr() in clock_was_set()

clock_was_set() can be invoked from preemptible context. Use raw_cpu_ptr()
to check whether high resolution mode is active or not. It does not matter
whether the task migrates after acquiring the pointer.

Fixes: e71a4153b7c2 ("hrtimer: Force clock_was_set() handling for the HIGHRES=n, NOHZ=y case")
Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/875ywacsmb.ffs@tglx

---
kernel/time/hrtimer.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 88aefc3..33b00e2 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -944,10 +944,11 @@ static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
*/
void clock_was_set(unsigned int bases)
{
+ struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
cpumask_var_t mask;
int cpu;

- if (!hrtimer_hres_active() && !tick_nohz_active)
+ if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
goto out_timerfd;

if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
@@ -958,9 +959,9 @@ void clock_was_set(unsigned int bases)
/* Avoid interrupting CPUs if possible */
cpus_read_lock();
for_each_online_cpu(cpu) {
- struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
unsigned long flags;

+ cpu_base = &per_cpu(hrtimer_bases, cpu);
raw_spin_lock_irqsave(&cpu_base->lock, flags);

if (update_needs_ipi(cpu_base, bases))