Commit 90dfeef1 authored Dec 04, 2025 by Peter Zijlstra Committed by Ingo Molnar Dec 06, 2025

seqlock: Cure some more scoped_seqlock() optimization fails



Arnd reported an x86 randconfig using gcc-15 tripped over
__scoped_seqlock_bug(). Turns out GCC chose not to inline the
scoped_seqlock helper functions and as such was not able to optimize
properly.

[ mingo: Clang fails the build too in some circumstances. ]

Reported-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://patch.msgid.link/20251204104332.GG2528459@noisy.programming.kicks-ass.net

parent 24bc5ea5

include/linux/seqlock.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -1224,7 +1224,7 @@ struct ss_tmp {
		spinlock_t *lock_irqsave;
		};

		static inline void __scoped_seqlock_cleanup(struct ss_tmp *sst)
		static __always_inline void __scoped_seqlock_cleanup(struct ss_tmp *sst)
		{
		if (sst->lock)
		spin_unlock(sst->lock);
		@@ -1252,7 +1252,7 @@ static inline void __scoped_seqlock_bug(void) { }
		extern void __scoped_seqlock_bug(void);
		#endif

		static inline void
		static __always_inline void
		__scoped_seqlock_next(struct ss_tmp sst, seqlock_t lock, enum ss_state target)
		{
		switch (sst->state) {