Messages in this thread | | | Date | Mon, 9 Dec 2013 09:43:16 +0800 | Subject | Re: [PATCH] xen/debugfs: Check debugfs initialization before using it | From | Ethan Zhao <> |
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On Sun, Dec 8, 2013 at 10:01 PM, Greg KH <gregkh@linuxfoundation.org> wrote: > On Sun, Dec 08, 2013 at 07:31:02PM +0800, ethan.zhao wrote: >> Should check debugfs initialization with debugfs_initialized() before using it, >> Because if it isn't initialized, the return value of fake debugfs_create_dir() etc >> functions would be ERR_PTR(-ENODEV), checking with NULL will not work. > > So? It should "just work" without this check, right? What happens if > your patch isn't applied and debugfs isn't enabled?
If debugfs isn't configured, debugfs_initialized() and other functions are defined as following,
static inline bool debugfs_initialized(void) { return false; }
static inline struct dentry *debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops) { return ERR_PTR(-ENODEV); }
static inline struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) { return ERR_PTR(-ENODEV); }
And the checking code in xen\debugfs.c xen_init_debugfs() will not work, the return value is not NULL. d_xen_debug = debugfs_create_dir("xen", NULL);
if (!d_xen_debug) pr_warning("Could not create 'xen' debugfs directory\n"); > > greg k-h > >> Signed-off-by: ethan.zhao <ethan.kernel@gmail.com> > > Please put your "real" name here, not one with a '.' in it.
The real name used in company is ethan.zhao@oracle.com, but I couldn't send and receive mails of community with that mailbox for some reason you may know.
Thanks, Ethan
> > thanks, > > greg k-h
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