Re: securityfs_create_dir strange comment
From: Greg KH
Date: Tue Feb 20 2007 - 23:07:35 EST
On Wed, Feb 21, 2007 at 12:45:40AM +0100, Jan Engelhardt wrote:
> On Feb 20 2007 14:26, Greg KH wrote:
> >On Tue, Feb 20, 2007 at 03:18:49PM -0600, Serge E. Hallyn wrote:
> >> Quoting Jan Engelhardt (jengelh@xxxxxxxxxxxxxxx):
> >> > Hello list,
> >> >
> >> >
> >> > in security/inode.c, the comment for securityfs_create_dir() reads:
> >> >
> >> > If securityfs is not enabled in the kernel, the value -ENODEV
> >> > will be returned. It is not wise to check for this value, but
> >> > rather, check for NULL or !NULL instead as to eliminate the need
> >> > for #ifdef in the calling code.
> >> >
> >> > What is the actual callee that can return NULL - and what should
> >> > module_init() of a module return when securityfs_create_dir() returns
> >> > NULL?
> >> Hmm, this came from GregKH. It does seem based on the code that
> >> checking for -ENODEV is necessary, so I don't understand the comment.
> >If securityfs_create_dir() returns NULL, then something bad happened and
> >your code needs to properly recover from it.
> >Other than that, I don't understand the issue here.
> static __init int mymodule_init(void)
> struct dentry *de;
> de = securityfs_create_dir("foobar", NULL);
> /* case 1 */
> return PTR_ERR(de);
> /* case 2 */
> if(de == NULL)
> return WHAT_HERE; /* -EIO? */
> There are two error cases. One: when the function gives us an error code.
> Two: When it returns NULL, without an error code. This looks bogus to me.
> What error is it, when there is no error? - And what should I return to
> modprobe in that case?
Try this instead:
if ((IS_ERR(de)) && (PTR_ERR(de) != -ENODEV))
That should cover everything properly, right?
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