Re: [PATCH/RFC 1/2] anon-inodes: Remove fd_install() fromanon_inode_getfd()

[Davide Libenzi]

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


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/