Messages in this thread Patch in this message | | | Date | Fri, 08 Aug 2014 12:35:36 +0200 | From | Bart Van Assche <> | Subject | [PATCH v3] spin_lock_nested(): Always evaluate second argument |
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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().
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> Cc: Ingo Molnar <mingo@kernel.org> Cc: David Rientjes <rientjes@google.com> 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 | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 3f2867f..262ba4e 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -197,7 +197,13 @@ 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) +/* + * Always evaluate the 'subclass' argument to avoid that the compiler + * warns about set-but-not-used variables when building with + * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1. + */ +# define raw_spin_lock_nested(lock, subclass) \ + _raw_spin_lock(((void)(subclass), (lock))) # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock) #endif -- 1.8.4.5
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