| Message ID | 1391630305-8056-1-git-send-email-marc.zyngier@arm.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Feb 05, 2014 at 07:58:25PM +0000, Marc Zyngier wrote: > Compiling with THP enabled leads to the following warning: > > arch/arm/kvm/mmu.c: In function ‘unmap_range’: > arch/arm/kvm/mmu.c:177:39: warning: ‘pte’ may be used uninitialized in this function [-Wmaybe-uninitialized] > if (kvm_pmd_huge(*pmd) || page_empty(pte)) { > ^ > Code inspection reveals that these two cases are mutually exclusive, > so GCC is a bit overzealous here. But silence it anyway by setting > pte to NULL if kvm_pmd_huge(*pmd) is true. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > arch/arm/kvm/mmu.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index ea21b6a..3020221 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -169,12 +169,14 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp, > pte = pte_offset_kernel(pmd, addr); > clear_pte_entry(kvm, pte, addr); > next = addr + PAGE_SIZE; > + } else { > + pte = NULL; > } If it's just for the compiler, how about just setting pte = NULL when pte is declared in the top of the function as to not interrupt the flow? -Christoffer
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index ea21b6a..3020221 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -169,12 +169,14 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp, pte = pte_offset_kernel(pmd, addr); clear_pte_entry(kvm, pte, addr); next = addr + PAGE_SIZE; + } else { + pte = NULL; } /* * If the pmd entry is to be cleared, walk back up the ladder */ - if (kvm_pmd_huge(*pmd) || page_empty(pte)) { + if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) { clear_pmd_entry(kvm, pmd, addr); next = pmd_addr_end(addr, end); if (page_empty(pmd) && !page_empty(pud)) {
Compiling with THP enabled leads to the following warning: arch/arm/kvm/mmu.c: In function ‘unmap_range’: arch/arm/kvm/mmu.c:177:39: warning: ‘pte’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (kvm_pmd_huge(*pmd) || page_empty(pte)) { ^ Code inspection reveals that these two cases are mutually exclusive, so GCC is a bit overzealous here. But silence it anyway by setting pte to NULL if kvm_pmd_huge(*pmd) is true. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm/kvm/mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)