From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:56550 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbdHaHOG (ORCPT ); Thu, 31 Aug 2017 03:14:06 -0400 Subject: Patch "lz4: fix bogus gcc warning" has been added to the 4.9-stable tree To: gregkh@linuxfoundation.org Cc: , From: Date: Thu, 31 Aug 2017 09:14:09 +0200 Message-ID: <150416364921711@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 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 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 From: Greg Kroah-Hartman Subject: lz4: fix bogus gcc warning From: Greg Kroah-Hartman 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 --- 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@linuxfoundation.org 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