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Date: Tue, 9 Dec 2008 11:08:39 +0100 From: Christian Borntraeger <borntraeger@...ibm.com> To: Avi Kivity <avi@...hat.com> Cc: Sheng Yang <sheng@...ux.intel.com>, kvm@...r.kernel.org, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 0/2] module_refcounting and anonymous inodes Am Dienstag, 9. Dezember 2008 schrieb Avi Kivity: > Sheng Yang wrote: > > Should we push the first patch to 2.6.28? > > It's not a recent regression, so no. > > > I got some trouble with the separate > > 2nd patch, for I am using Linus' tree and make KVM as modules, so the > > reference count reduced to negative now... (Oh Avi, I know you suggest to use > > in kernel rather than modules, but module is indeed convenient. :) ) > > > > Right, that would affect everyone. What we need is to hack the second > patch for external modules on <2.6.29. Oh this is tricky. Both patches belong together, patch 2 depends on patch 1. For base kernels which do not contain patch1, this additional (untested) patch would probably help: --- virt/kvm/kvm_main.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) Index: kvm/virt/kvm/kvm_main.c =================================================================== --- kvm.orig/virt/kvm/kvm_main.c +++ kvm/virt/kvm/kvm_main.c @@ -1501,9 +1501,15 @@ static struct file_operations kvm_vcpu_f */ static int create_vcpu_fd(struct kvm_vcpu *vcpu) { - int fd = anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0); - if (fd < 0) + int fd; + + if (!try_module_get(kvm_vcpu_fops.owner)) + return -ENOENT; + fd = anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0); + if (fd < 0) { kvm_put_kvm(vcpu->kvm); + module_put(kvm_vcpu_fops.owner); + } return fd; } @@ -1895,12 +1901,19 @@ static int kvm_dev_ioctl_create_vm(void) int fd; struct kvm *kvm; + if (!try_module_get(kvm_vm_fops.owner)) + return -ENOENT; + kvm = kvm_create_vm(); - if (IS_ERR(kvm)) + if (IS_ERR(kvm)) { + module_put(kvm_vm_fops.owner); return PTR_ERR(kvm); + } fd = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, 0); - if (fd < 0) + if (fd < 0) { kvm_put_kvm(kvm); + module_put(kvm_vm_fops.owner); + } return fd; } The problem is, how do you detect if the base kernel has patch1 applied? Christian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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