The current annotation uses a global variable as recursion counter.
The variable is not atomic nor protected with a mutex, but mutated
by multiple threads. This causes lockdep bug reports episodically:
BUG: looking up invalid subclass: 4294967295
...
_raw_spin_lock_irqsave_nested+0x120/0x180
hashbin_delete+0x4fe/0x750
__irias_delete_object+0xab/0x170
irias_delete_object+0x5f/0xc0
ircomm_tty_detach_cable+0x1d5/0x3f0
...
Make the hashbin_lock_depth variable atomic to prevent bug reports.
As is this causes "unused variable 'depth'" warning without LOCKDEP.
So also change raw_spin_lock_irqsave_nested() macro to not cause
the warning without LOCKDEP. Similar to what raw_spin_lock_nested()
already does.
Signed-off-by: Dmitry Vyukov <dvyu...@google.com>
Cc: Dave Jones <da...@redhat.com>
Cc: Samuel Ortiz <sam...@sortiz.org>
Cc: David S. Miller <da...@davemloft.net>
Cc: netdev@vger.kernel.org
Fixes: c7630a4b932af ("[IrDA]: irda lockdep annotation")
---
Changes since v1:
- Added raw_spin_lock_irqsave_nested() change
as 0-DAY bot reported compiler warning without LOCKDEP.
Changes since v2:
- Use ((void)(subclass), (lock)) instead of (void)subclass
to prevent unused variable warning. Now 0-DAY complaints
"error: void value not ignored as it ought to be".
My compiler does not produce warning with W=1 either way,
but the comma trick is what already used in raw_spin_lock_nested().
---
include/linux/spinlock.h | 2 +-
net/irda/irqueue.c | 12 +++++++-----
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 47dd0cebd204..beeb5a39bd8b 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -218,7 +218,7 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock)
__releases(lock)
#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
do { \
typecheck(unsigned long, flags); \
- flags = _raw_spin_lock_irqsave(lock); \
+ flags = _raw_spin_lock_irqsave(((void)(subclass), (lock))); \
} while (0)
#endif
diff --git a/net/irda/irqueue.c b/net/irda/irqueue.c
index acbe61c7e683..b9fd74e6ca99 100644
--- a/net/irda/irqueue.c
+++ b/net/irda/irqueue.c
@@ -384,21 +384,23 @@ EXPORT_SYMBOL(hashbin_new);
* just supply kfree, which should take care of the job.
*/
#ifdef CONFIG_LOCKDEP
-static int hashbin_lock_depth = 0;
+static atomic_t hashbin_lock_depth = ATOMIC_INIT(0);
#endif
int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
{
irda_queue_t* queue;
unsigned long flags = 0;
- int i;
+ int i, depth = 0;
IRDA_ASSERT(hashbin != NULL, return -1;);
IRDA_ASSERT(hashbin->magic == HB_MAGIC, return -1;);
/* Synchronize */
if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_irqsave_nested(&hashbin->hb_spinlock, flags,
- hashbin_lock_depth++);
+#ifdef CONFIG_LOCKDEP
+ depth = atomic_inc_return(&hashbin_lock_depth) - 1;
+#endif
+ spin_lock_irqsave_nested(&hashbin->hb_spinlock, flags, depth);
}
/*
@@ -423,7 +425,7 @@ int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
if ( hashbin->hb_type & HB_LOCK) {
spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
#ifdef CONFIG_LOCKDEP
- hashbin_lock_depth--;
+ atomic_dec(&hashbin_lock_depth);
#endif
}
--
2.11.0.483.g087da7b7c-goog
