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    SubjectRe: [PATCH/RFC 1/2] anon-inodes: Remove fd_install() from anon_inode_getfd()
    On Wed, 27 Feb 2008, Roland Dreier wrote:

    > > http://git.kernel.org/?p=linux/kernel/git/viro/vfs-2.6.git;a=commit;h=49be4f8114e6ff0efdab10ebba2493fb67bc3034
    >
    > Actually, looking closer at the kvm changes here, I think that
    > create_vcpu_fd() needs the same treatment as kvm_dev_ioctl_create_vm()
    > gets in the patch because of the race I mentioned in the changelog
    > for my patch: otherwise kvm_vcpu_release() could drop the last
    > reference to vcpu->kvm->filp before the get_file() gets an extra
    > reference.
    >
    > I'm beginning to think that moving the fd_install() out of
    > anon_inode_getfd() really is worth it to make a safer interface.

    If we let the caller call fd_install(), then it may be messed up WRT
    cleanup (fd, file, inode).
    How about removing the inode pointer handout altogether, and *doing*
    fd_install() inside anon_inode_getfd() like:

    if (pfile != NULL) {
    get_file(file);
    *pfile = file;
    }
    fd_install(fd, file);

    In this way, if the caller want the file* back, he gets the reference
    bumped before fd_install().



    - Davide




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