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KVM: MIPS: Fix maybe-uninitialized build failure

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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 <James.Cowgill@imgtec.com>
Fixes: 57e3869cfa ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID")
Cc: <stable@vger.kernel.org> # 4.11+
Acked-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
James Cowgill 2017-06-20 10:57:51 +01:00 committed by Radim Krčmář
parent c72544d85f
commit e27a9eca5d
1 changed files with 5 additions and 1 deletions
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6
arch/mips/kvm/tlb.c
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@ -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);