Messages in this thread | | | Date | Mon, 9 Dec 2013 00:25:27 -0800 | From | Greg KH <> | Subject | Re: [PATCH] xen/debugfs: Check debugfs initialization before using it |
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On Mon, Dec 09, 2013 at 09:43:16AM +0800, Ethan Zhao wrote: > 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");
Which is just fine, what is wrong with this?
> > > > 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.
I mean the "ethan.zhao" part, it should be "Ethan Zhao" :)
thanks,
greg k-h
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