This is a note to let you know that I've just added the patch titled
lz4: fix bogus gcc warning
to the 4.9-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:
lz4-fix-bogus-gcc-warning.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Aug 31 09:09:54 CEST 2017
Date: Thu, 31 Aug 2017 09:09:54 +0200
To: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Subject: lz4: fix bogus gcc warning
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
---
lib/lz4/lz4hc_compress.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/lib/lz4/lz4hc_compress.c
+++ b/lib/lz4/lz4hc_compress.c
@@ -131,7 +131,7 @@ static inline int lz4hc_insertandfindbes
#endif
int nbattempts = MAX_NB_ATTEMPTS;
size_t repl = 0, ml = 0;
- u16 delta;
+ u16 delta = 0;
/* HC4 match finder */
lz4hc_insert(hc4, ip);
Patches currently in stable-queue which might be from gregkh@xxxxxxxxxxxxxxxxxxx are
queue-4.9/scsi-sg-protect-accesses-to-reserved-page-array.patch
queue-4.9/locking-spinlock-debug-remove-spinlock-lockup-detection-code.patch
queue-4.9/p54-memset-0-whole-array.patch
queue-4.9/lz4-fix-bogus-gcc-warning.patch
queue-4.9/x86-io-add-memory-clobber-to-insb-insw-insl-outsb-outsw-outsl.patch
queue-4.9/gcov-support-gcc-7.1.patch
queue-4.9/staging-wilc1000-simplify-vif-ndev-accesses.patch
queue-4.9/arm64-fpsimd-prevent-registers-leaking-across-exec.patch
queue-4.9/scsi-isci-avoid-array-subscript-warning.patch
queue-4.9/arm64-mm-abort-uaccess-retries-upon-fatal-signal.patch
queue-4.9/kvm-arm-arm64-fix-race-in-resetting-stage2-pgd.patch
queue-4.9/scsi-sg-reset-res_in_use-after-unlinking-reserved-array.patch