Patch "smc91x: avoid self-comparison warning" has been added to the 4.4-stable tree

Patch "smc91x: avoid self-comparison warning" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    smc91x: avoid self-comparison warning

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     smc91x-avoid-self-comparison-warning.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e3ebd894f084255fde19116955ba7054858ff5d6 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 14 Mar 2016 23:45:12 +0100
Subject: smc91x: avoid self-comparison warning

From: Arnd Bergmann <arnd@arndb.de>

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@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/ethernet/smsc/smc91x.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/smsc/smc91x.c
+++ b/drivers/net/ethernet/smsc/smc91x.c
@@ -540,7 +540,7 @@ static inline void  smc_rcv(struct net_d
 #define smc_special_lock(lock, flags)		spin_lock_irqsave(lock, flags)
 #define smc_special_unlock(lock, flags) 	spin_unlock_irqrestore(lock, flags)
 #else
-#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)
 #endif


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-4.4/drm-exynos-fix-error-handling-in-exynos_drm_subdrv_open.patch
queue-4.4/arm-8584-1-floppy-avoid-gcc-6-warning.patch
queue-4.4/powerpc-ptrace-fix-out-of-bounds-array-access-warning.patch
queue-4.4/cgroup-avoid-false-positive-gcc-6-warning.patch
queue-4.4/smc91x-avoid-self-comparison-warning.patch