On Mon, 20 Jan 2025 18:56:57 -0500 Steven Rostedt rostedt@goodmis.org wrote:
From: Steven Rostedt rostedt@goodmis.org
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 is an architecture specific operation, 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.
Looks good to me.
Reviewed-by: Masami Hiramatsu (Google) mhiramat@kernel.org
Thanks,
Cc: stable@vger.kernel.org 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 Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
lib/atomic64.c | 78 +++++++++++++++++++++++++++++++------------------- 1 file changed, 48 insertions(+), 30 deletions(-)
diff --git a/lib/atomic64.c b/lib/atomic64.c index caf895789a1e..1a72bba36d24 100644 --- 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(const atomic64_t *v) 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##_return); 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_positive); 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; } -- 2.45.2