Daniel Walker wrote:
It looks possible that the PLL and clock functions might get into a condition
when these stack variables would get used/returned with uninitialized
data . So it needs further review ..
May I veto this? Please fix gcc instead, it does its analysis incorrectly.
matroxfb_PLL_mavenclock either returns 0, or initializes all arguments it gets (if
not, then please show me code path which returns non-zero and does not set
h2/post/in/feed). And matroxfb_mavenclock either returns EINVAL, or sets *post.
And a,b & h2 are used in maven_find_exact_clocks() are used only if
matroxfb_mavenclock returned 0 - and in this case a,b & h2 were always set.
Thanks,
Petr Vandrovec
Fixes the following warning,
drivers/video/matrox/matroxfb_maven.c: In function 'maven_out_compute':
drivers/video/matrox/matroxfb_maven.c:287: warning: 'p' may be used uninitialized in this function
drivers/video/matrox/matroxfb_maven.c:718: warning: 'h2' may be used uninitialized in this function
drivers/video/matrox/matroxfb_maven.c:718: warning: 'b' may be used uninitialized in this function
drivers/video/matrox/matroxfb_maven.c:718: warning: 'a' may be used uninitialized in this function
P.S.: It is off-topic for LKML, but this one is my favorite, it comes from
ncpfs I maintain...
vana:/usr/src/hg/ncpfs/lib# cat test.c
#include <pthread.h>
#include <stdio.h>
pthread_mutex_t nds_ring_lock;
extern int test(void);
static int __NWCCGetServerAddressPtr(int* count) {
if (test()) {
return 1;
}
*count = 0;
return 0;
}
void NWDXFindConnection(void) {
int connaddresses;
int err2;
pthread_mutex_lock(&nds_ring_lock);
err2 = __NWCCGetServerAddressPtr(&connaddresses);
pthread_mutex_unlock(&nds_ring_lock);
if (err2)
return;
printf("ConnAddress is uninitialized? %u\n", connaddresses);
}
vana:/usr/src/hg/ncpfs/lib# gcc -v -O2 -W -c test.c
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --program-suffix=-4.0 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-awt=gtk-default --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --with-tune=i686 --enable-checking=release i486-linux-gnu
Thread model: posix
...
gcc version 4.0.4 20060422 (prerelease) (Debian 4.0.3-2)
GNU C version 4.0.4 20060422 (prerelease) (Debian 4.0.3-2) (i486-linux-gnu)
compiled by GNU C version 4.0.4 20060422 (prerelease) (Debian 4.0.3-2).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
test.c: In function 'NWDXFindConnection':
test.c:17: warning: 'connaddresses' may be used uninitialized in this function
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