From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Cowgill Subject: [PATCH v2] KVM: MIPS: Fix maybe-uninitialized build failure Date: Tue, 20 Jun 2017 10:57:51 +0100 Message-ID: <20170620095751.5443-1-James.Cowgill@imgtec.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Cc: Ralf Baechle , , , James Cowgill To: James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Return-path: Received: from mailapp01.imgtec.com ([195.59.15.196]:51909 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750925AbdFTJ6T (ORCPT ); Tue, 20 Jun 2017 05:58:19 -0400 Sender: kvm-owner@vger.kernel.org List-ID: This commit fixes a "maybe-uninitialized" build failure in arch/mips/kvm/tlb.c when KVM, DYNAMIC_DEBUG and JUMP_LABEL are all enabled. The failure is: In file included from ./include/linux/printk.h:329:0, from ./include/linux/kernel.h:13, from ./include/asm-generic/bug.h:15, from ./arch/mips/include/asm/bug.h:41, from ./include/linux/bug.h:4, from ./include/linux/thread_info.h:11, from ./include/asm-generic/current.h:4, from ./arch/mips/include/generated/asm/current.h:1, from ./include/linux/sched.h:11, from arch/mips/kvm/tlb.c:13: arch/mips/kvm/tlb.c: In function ‘kvm_mips_host_tlb_inv’: ./include/linux/dynamic_debug.h:126:3: error: ‘idx_kernel’ may be used uninitialized in this function [-Werror=maybe-uninitialized] __dynamic_pr_debug(&descriptor, pr_fmt(fmt), \ ^~~~~~~~~~~~~~~~~~ arch/mips/kvm/tlb.c:169:16: note: ‘idx_kernel’ was declared here int idx_user, idx_kernel; ^~~~~~~~~~ There is a similar error relating to "idx_user". Both errors were observed with GCC 6. As far as I can tell, it is impossible for either idx_user or idx_kernel to be uninitialized when they are later read in the calls to kvm_debug, but to satisfy the compiler, add zero initializers to both variables. Signed-off-by: James Cowgill Fixes: 57e3869cfaae ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID") Cc: # 4.11+ --- arch/mips/kvm/tlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index 7c6336dd2638..7cd92166a0b9 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -166,7 +166,11 @@ static int _kvm_mips_host_tlb_inv(unsigned long entryhi) int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va, bool user, bool kernel) { - int idx_user, idx_kernel; + /* + * Initialize idx_user and idx_kernel to workaround bogus + * maybe-initialized warning when using GCC 6. + */ + int idx_user = 0, idx_kernel = 0; unsigned long flags, old_entryhi; local_irq_save(flags); -- 2.11.0