6.12-stable review patch. If anyone has any objections, please let me know.
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From: Steven Rostedt rostedt@goodmis.org
commit 6c8ad3ab45ad0e94bfb7a9c71f2fa9c6cacea4b2 upstream.
raw_spin_locks can be traced by lockdep or tracing itself. Atomic64 operations can be used in the tracing infrastructure. When an architecture does not have true atomic64 operations it can use the generic version that disables interrupts and uses spin_locks.
The tracing ring buffer code uses atomic64 operations for the time keeping. But because some architectures use the default operations, the locking inside the atomic operations can cause an infinite recursion.
As atomic64 implementation is architecture specific, it should not be using raw_spin_locks() but instead arch_spin_locks as that is the purpose of arch_spin_locks. To be used in architecture specific implementations of generic infrastructure like atomic64 operations.
Note, by switching from raw_spin_locks to arch_spin_locks, the locks taken to emulate the atomic64 operations will not have lockdep, mmio, or any kind of checks done on them. They will not even disable preemption, although the code will disable interrupts preventing the tasks that hold the locks from being preempted. As the locks held are done so for very short periods of time, and the logic is only done to emulate atomic64, not having them be instrumented should not be an issue.
Cc: stable@vger.kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Andreas Larsson andreas@gaisler.com Link: https://lore.kernel.org/20250122144311.64392baf@gandalf.local.home Fixes: c84897c0ff592 ("ring-buffer: Remove 32bit timestamp logic") Closes: https://lore.kernel.org/all/86fb4f86-a0e4-45a2-a2df-3154acc4f086@gaisler.com... Reported-by: Ludwig Rydberg ludwig.rydberg@gaisler.com Reviewed-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/atomic64.c | 78 +++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 48 insertions(+), 30 deletions(-)
--- a/lib/atomic64.c +++ b/lib/atomic64.c @@ -25,15 +25,15 @@ * Ensure each lock is in a separate cacheline. */ static union { - raw_spinlock_t lock; + arch_spinlock_t lock; char pad[L1_CACHE_BYTES]; } atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = { [0 ... (NR_LOCKS - 1)] = { - .lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock), + .lock = __ARCH_SPIN_LOCK_UNLOCKED, }, };
-static inline raw_spinlock_t *lock_addr(const atomic64_t *v) +static inline arch_spinlock_t *lock_addr(const atomic64_t *v) { unsigned long addr = (unsigned long) v;
@@ -45,12 +45,14 @@ static inline raw_spinlock_t *lock_addr( s64 generic_atomic64_read(const atomic64_t *v) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v); s64 val;
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); val = v->counter; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags); return val; } EXPORT_SYMBOL(generic_atomic64_read); @@ -58,11 +60,13 @@ EXPORT_SYMBOL(generic_atomic64_read); void generic_atomic64_set(atomic64_t *v, s64 i) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v);
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); v->counter = i; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags); } EXPORT_SYMBOL(generic_atomic64_set);
@@ -70,11 +74,13 @@ EXPORT_SYMBOL(generic_atomic64_set); void generic_atomic64_##op(s64 a, atomic64_t *v) \ { \ unsigned long flags; \ - raw_spinlock_t *lock = lock_addr(v); \ + arch_spinlock_t *lock = lock_addr(v); \ \ - raw_spin_lock_irqsave(lock, flags); \ + local_irq_save(flags); \ + arch_spin_lock(lock); \ v->counter c_op a; \ - raw_spin_unlock_irqrestore(lock, flags); \ + arch_spin_unlock(lock); \ + local_irq_restore(flags); \ } \ EXPORT_SYMBOL(generic_atomic64_##op);
@@ -82,12 +88,14 @@ EXPORT_SYMBOL(generic_atomic64_##op); s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v) \ { \ unsigned long flags; \ - raw_spinlock_t *lock = lock_addr(v); \ + arch_spinlock_t *lock = lock_addr(v); \ s64 val; \ \ - raw_spin_lock_irqsave(lock, flags); \ + local_irq_save(flags); \ + arch_spin_lock(lock); \ val = (v->counter c_op a); \ - raw_spin_unlock_irqrestore(lock, flags); \ + arch_spin_unlock(lock); \ + local_irq_restore(flags); \ return val; \ } \ EXPORT_SYMBOL(generic_atomic64_##op##_return); @@ -96,13 +104,15 @@ EXPORT_SYMBOL(generic_atomic64_##op##_re s64 generic_atomic64_fetch_##op(s64 a, atomic64_t *v) \ { \ unsigned long flags; \ - raw_spinlock_t *lock = lock_addr(v); \ + arch_spinlock_t *lock = lock_addr(v); \ s64 val; \ \ - raw_spin_lock_irqsave(lock, flags); \ + local_irq_save(flags); \ + arch_spin_lock(lock); \ val = v->counter; \ v->counter c_op a; \ - raw_spin_unlock_irqrestore(lock, flags); \ + arch_spin_unlock(lock); \ + local_irq_restore(flags); \ return val; \ } \ EXPORT_SYMBOL(generic_atomic64_fetch_##op); @@ -131,14 +141,16 @@ ATOMIC64_OPS(xor, ^=) s64 generic_atomic64_dec_if_positive(atomic64_t *v) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v); s64 val;
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); val = v->counter - 1; if (val >= 0) v->counter = val; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags); return val; } EXPORT_SYMBOL(generic_atomic64_dec_if_positive); @@ -146,14 +158,16 @@ EXPORT_SYMBOL(generic_atomic64_dec_if_po s64 generic_atomic64_cmpxchg(atomic64_t *v, s64 o, s64 n) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v); s64 val;
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); val = v->counter; if (val == o) v->counter = n; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags); return val; } EXPORT_SYMBOL(generic_atomic64_cmpxchg); @@ -161,13 +175,15 @@ EXPORT_SYMBOL(generic_atomic64_cmpxchg); s64 generic_atomic64_xchg(atomic64_t *v, s64 new) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v); s64 val;
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); val = v->counter; v->counter = new; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags); return val; } EXPORT_SYMBOL(generic_atomic64_xchg); @@ -175,14 +191,16 @@ EXPORT_SYMBOL(generic_atomic64_xchg); s64 generic_atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u) { unsigned long flags; - raw_spinlock_t *lock = lock_addr(v); + arch_spinlock_t *lock = lock_addr(v); s64 val;
- raw_spin_lock_irqsave(lock, flags); + local_irq_save(flags); + arch_spin_lock(lock); val = v->counter; if (val != u) v->counter += a; - raw_spin_unlock_irqrestore(lock, flags); + arch_spin_unlock(lock); + local_irq_restore(flags);
return val; }