[PATCH 3.12 044/127] smc91x: avoid self-comparison warning

From: Jiri Slaby
Date: Fri Nov 25 2016 - 03:59:46 EST

From: Arnd Bergmann <arnd@xxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit e3ebd894f084255fde19116955ba7054858ff5d6 upstream.

The smc91x driver defines a macro that compares its argument to
itself, apparently to get a true result while using its argument
to avoid a warning about unused local variables.

Unfortunately, this triggers a warning with gcc-6, as the comparison
is obviously useless:

drivers/net/ethernet/smsc/smc91x.c: In function 'smc_hardware_send_pkt':
drivers/net/ethernet/smsc/smc91x.c:563:14: error: self-comparison always evaluates to true [-Werror=tautological-compare]
if (!smc_special_trylock(&lp->lock, flags)) {

This replaces the macro with another one that behaves similarly,
with a cast to (void) to ensure the argument is used, and using
a literal 'true' as its value.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
drivers/net/ethernet/smsc/smc91x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/smsc/smc91x.c b/drivers/net/ethernet/smsc/smc91x.c
index 73be7f3982e6..af9e7d775348 100644
--- a/drivers/net/ethernet/smsc/smc91x.c
+++ b/drivers/net/ethernet/smsc/smc91x.c
@@ -533,7 +533,7 @@ static inline void smc_rcv(struct net_device *dev)
#define smc_special_lock(lock, flags) spin_lock_irqsave(lock, flags)
#define smc_special_unlock(lock, flags) spin_unlock_irqrestore(lock, flags)
-#define smc_special_trylock(lock, flags) (flags == flags)
+#define smc_special_trylock(lock, flags) ((void)flags, true)
#define smc_special_lock(lock, flags) do { flags = 0; } while (0)
#define smc_special_unlock(lock, flags) do { flags = 0; } while (0)