| Message ID | 20220401100147.GA29786@kili (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: MMU: fix an IS_ERR() vs NULL bug | expand |
On Fri, Apr 01, 2022, Dan Carpenter wrote: > The alloc_workqueue() function does not return error pointers, it > returns NULL on error. Update the check accordingly. > > Fixes: 1a3320dd2939 ("KVM: MMU: propagate alloc_workqueue failure") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> > --- Reviewed-by: Sean Christopherson <seanjc@google.com> > Obviously, I noticed that the patch says "propagate alloc_workqueue > failure" so that's a puzzling thing. Merge issue perhaps? In > linux-next it alloc_workqueue() returns NULL. No merge issue, just a goof. The "propagate" patch was added because KVM neglected to check for allocation failure, so at least it was a step in the right direction :-) > arch/x86/kvm/mmu/tdp_mmu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index a2f9a34a0168..d71d177ae6b8 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -22,8 +22,8 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm) > return 0; > > wq = alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0); > - if (IS_ERR(wq)) > - return PTR_ERR(wq); > + if (!wq) > + return -ENOMEM; > > /* This should not be changed for the lifetime of the VM. */ > kvm->arch.tdp_mmu_enabled = true; > -- Paolo, any objection to also returning '0' in all non-error paths? There's no need to return whether or not the TDP MMU is enabled since that's handled locally, and the "return 1" is rather odd. diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index dbf46dd98618..dec32b4a13aa 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5779,7 +5779,7 @@ int kvm_mmu_init_vm(struct kvm *kvm) spin_lock_init(&kvm->arch.mmu_unsync_pages_lock); r = kvm_mmu_init_tdp_mmu(kvm); - if (r < 0) + if (r) return r; node->track_write = kvm_mmu_pte_write; diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index a2f9a34a0168..3a60b999e1aa 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -31,7 +31,7 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm) spin_lock_init(&kvm->arch.tdp_mmu_pages_lock); INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages); kvm->arch.tdp_mmu_zap_wq = wq; - return 1; + return 0; } /* Arbitrarily returns true so that this may be used in if statements. */
On 4/1/22 16:04, Sean Christopherson wrote: > Paolo, any objection to also returning '0' in all non-error paths? There's no > need to return whether or not the TDP MMU is enabled since that's handled locally, > and the "return 1" is rather odd. Well, I kept that because I thought there was a hidden reason for that. At this point I was really about to press Enter and send out the pull request, so... Paolo
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index a2f9a34a0168..d71d177ae6b8 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -22,8 +22,8 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm) return 0; wq = alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0); - if (IS_ERR(wq)) - return PTR_ERR(wq); + if (!wq) + return -ENOMEM; /* This should not be changed for the lifetime of the VM. */ kvm->arch.tdp_mmu_enabled = true;
The alloc_workqueue() function does not return error pointers, it returns NULL on error. Update the check accordingly. Fixes: 1a3320dd2939 ("KVM: MMU: propagate alloc_workqueue failure") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- Obviously, I noticed that the patch says "propagate alloc_workqueue failure" so that's a puzzling thing. Merge issue perhaps? In linux-next it alloc_workqueue() returns NULL. arch/x86/kvm/mmu/tdp_mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)