lz4: fix bogus gcc warning
When building lz4 under gcc-7 we get the following bogus warning:
CC [M] lib/lz4/lz4hc_compress.o
lib/lz4/lz4hc_compress.c: In function ‘lz4hc_compress’:
lib/lz4/lz4hc_compress.c:179:42: warning: ‘delta’ may be used uninitialized in this function [-Wmaybe-uninitialized]
chaintable[(size_t)(ptr) & MAXD_MASK] = delta;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
lib/lz4/lz4hc_compress.c:134:6: note: ‘delta’ was declared here
u16 delta;
^~~~~
This doesn't show up in the 4.4-stable tree due to us turning off
warnings like this. It also doesn't show up in newer kernel versions as
this code was totally rewritten.
So for now, to get the 4.9-stable tree to build with 0 warnings on x86
allmodconfig, let's just shut the compiler up by initializing the
variable to 0, despite it not really doing anything.
To be far, this code is crazy complex, so the fact that gcc can't
determine if the variable is really used or not isn't that bad, I'd
blame the code here instead of the compiler.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c
index f344f76..6b2e046 100644
--- a/lib/lz4/lz4hc_compress.c
+++ b/lib/lz4/lz4hc_compress.c
@@ -131,7 +131,7 @@
#endif
int nbattempts = MAX_NB_ATTEMPTS;
size_t repl = 0, ml = 0;
- u16 delta;
+ u16 delta = 0;
/* HC4 match finder */
lz4hc_insert(hc4, ip);