Re: [PATCH v4] mtd: spi-nor: fix memory leak when using debugfs_lookup()

[Greg Kroah-Hartman]

On Wed, Feb 08, 2023 at 05:15:41PM +0100, Michael Walle wrote:
> Am 2023-02-08 17:02, schrieb Greg Kroah-Hartman:
> > When calling debugfs_lookup() the result must have dput() called on it,
> > otherwise the memory will leak over time.  To solve this, remove the
> > lookup and create the directory on the first device found, and then
> > remove it when the module is unloaded.
> > 
> > Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
> > Cc: Pratyush Yadav <pratyush@xxxxxxxxxx>
> > Cc: Michael Walle <michael@xxxxxxxx>
> > Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > Cc: Richard Weinberger <richard@xxxxxx>
> > Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
> > Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> Reviewed-by: Michael Walle <michael@xxxxxxxx>
> 
> one nit below I didn't notice earlier, no need to send a new
> patch version just for that.
> 
> ..
> 
> > +void spi_nor_debugfs_shutdown(void)
> > +{
> > +	if (rootdir)
> > +		debugfs_remove(rootdir);
> 
> debugfs_remove() already has a check for NULL.
> 

Argh, I knew that, for some reason I went back and added that check as I
was thinking this would have been an issue if rootdir was never created.
You are right, it isn't a problem, oh well.

The simplest patches sometimes take the longest time to get right, I'll
stop now :)

thanks so much for the reviews,

greg k-h