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| author |   Bart Van Assche <bvanassche@acm.org> | 2014-08-08 12:35:36 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2014-08-13 10:32:38 +0200 |
| commit | 4999201a59ef555f9105d2bb2459ed895627f7aa (patch) | |
| tree | 51148e7d68b8dd47f50344020b489aa20cb459e0 /include/linux/spinlock.h | |
| parent | locking/Documentation: Update locking/mutex-design.txt disadvantages (diff) | |
| download | wireguard-linux-4999201a59ef555f9105d2bb2459ed895627f7aa.tar.xz wireguard-linux-4999201a59ef555f9105d2bb2459ed895627f7aa.zip | |
locking/spinlocks: Always evaluate the second argument of spin_lock_nested()
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>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/53E4A7F8.1040700@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/spinlock.h')
| -rw-r--r-- | include/linux/spinlock.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 3f2867ff0ced..262ba4ef9a8e 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 |