From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 27 Jan 2016 16:21:54 +0100 Subject: [PATCH 8/9] net: nb8800: avoid uninitialized variable warning In-Reply-To: References: <1453903507-3427225-1-git-send-email-arnd@arndb.de> <1453903507-3427225-9-git-send-email-arnd@arndb.de> Message-ID: <8558854.EA4z9rFkjX@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wednesday 27 January 2016 14:13:16 M?ns Rullg?rd wrote: > Arnd Bergmann writes: > > > The nb8800_poll() function initializes the 'next' variable in the > > loop looking for new input data. We know this will be called at > > least once because 'budget' is a guaranteed to be a positive number > > when we enter the function, but the compiler doesn't know that > > and warns when the variable is used later: > > > > drivers/net/ethernet/aurora/nb8800.c: In function 'nb8800_poll': > > drivers/net/ethernet/aurora/nb8800.c:350:21: warning: 'next' may be used uninitialized in this function [-Wmaybe-uninitialized] > > Which gcc version is this? 4.9 doesn't warn here, presumably because > it's clever enough to notice that the offending use of 'next' is under a > condition that can only be true if the first one was. Of course fixing > the code so older compilers don't warn is a good idea. This was with gcc-5.2.1, but possibly in an unusual kernel configuration. The only time I see it in my logs was with CONFIG_ARCH_IXP4XX=y, which has its own mach/io.h and other headers that sometimes override generic functions with a more elaborate version. I have another patch for ixp4xx that simplifies its mach/io.h in order to get rid of other false 'uninitialized use' warnings, but this one still shows up with that other patch. > > Changing the 'while() {}' loop to 'do {} while()' makes it obvious > > to the compiler what is going on so it no longer warns. > > > > Signed-off-by: Arnd Bergmann > > Acked-by: Mans Rullgard Thanks, Arnd