Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'locking-urgent-2025-11-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Ingo Molnar:
"Fix (well, cut in half) a futex performance regression on PowerPC"
* tag 'locking-urgent-2025-11-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Optimize per-cpu reference counting
+6
-6
+6
-6
kernel/futex/core.c
+6
-6
kernel/futex/core.c
···
1680
1680
{
1681
1681
struct mm_struct *mm = fph->mm;
1682
1682
1683
-
guard(rcu)();
1683
+
guard(preempt)();
1684
1684
1685
-
if (smp_load_acquire(&fph->state) == FR_PERCPU) {
1686
-
this_cpu_inc(*mm->futex_ref);
1685
+
if (READ_ONCE(fph->state) == FR_PERCPU) {
1686
+
__this_cpu_inc(*mm->futex_ref);
1687
1687
return true;
1688
1688
}
1689
1689
···
1694
1694
{
1695
1695
struct mm_struct *mm = fph->mm;
1696
1696
1697
-
guard(rcu)();
1697
+
guard(preempt)();
1698
1698
1699
-
if (smp_load_acquire(&fph->state) == FR_PERCPU) {
1700
-
this_cpu_dec(*mm->futex_ref);
1699
+
if (READ_ONCE(fph->state) == FR_PERCPU) {
1700
+
__this_cpu_dec(*mm->futex_ref);
1701
1701
return false;
1702
1702
}
1703
1703