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Subject[PATCH RESEND] spin_lock_*(): Always evaluate second argument
Evaluating a macro argument only if certain configuration options
have been selected is confusing and error-prone. Hence always
evaluate the second argument of spin_lock_nested() and
spin_lock_nest_lock().

An intentional side effect of this patch is that it avoids that
the following warning is reported for netif_addr_lock_nested()
when building with CONFIG_DEBUG_LOCK_ALLOC=n and with W=1:

include/linux/netdevice.h: In function 'netif_addr_lock_nested':
include/linux/netdevice.h:2865:6: warning: variable 'subclass' set but not used [-Wunused-but-set-variable]
int subclass = SINGLE_DEPTH_NESTING;
^

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/spinlock.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 3f2867f..32b16cc 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -197,8 +197,10 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
_raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
} while (0)
#else
-# define raw_spin_lock_nested(lock, subclass) _raw_spin_lock(lock)
-# define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
+# define raw_spin_lock_nested(lock, subclass) \
+ ((void)(subclass), _raw_spin_lock(lock))
+# define raw_spin_lock_nest_lock(lock, nest_lock) \
+ ((void)(nest_lock), _raw_spin_lock(lock))
#endif

#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
--
1.8.4.5


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