On Mon, Apr 24, 2017 at 09:44:50PM -0400, David Miller wrote: > From: Myungho Jung <mhju...@gmail.com> > Date: Mon, 24 Apr 2017 18:00:52 -0700 > > > On Mon, Apr 24, 2017 at 12:02:35PM -0400, David Miller wrote: > >> From: Myungho Jung <mhju...@gmail.com> > >> Date: Thu, 20 Apr 2017 16:59:20 -0700 > >> > >> > Added NULL check to make __dev_kfree_skb_irq consistent with kfree > >> > family of functions. > >> > > >> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=195289 > >> > > >> > Signed-off-by: Myungho Jung <mhju...@gmail.com> > >> > --- > >> > Changes in v2: > >> > - Correct category in subject > >> > >> This subject line is an incomplete sentence. > >> > >> This patch prevents dereferenccing a null pointer when "what"? > > > > As it was reported on bugzilla, it would happen when plugging p54 usb device > > to RPi2. But, i'm not 100% sure that this patch will resolve the issue > > because > > the reporter didn't try my patch yet and I don't have the device to test. > > > > And there might be some other places calling the function without checking > > null pointer. The thing is that only the function don't check null among > > kfree functions. So, I just hope this patch will prevent potential oops > > issues. > > It doesn't check for a NULL pointer because it is almost exclusively > used in the interrupt paths where we know we have a non-NULL skb.
Yes, actually null is checked before calling the function in most cases. That's why my first patch was applied not to net/core but to p54 driver because I was worried about duplicated checking. But, Christian suggested this patch to make it consistent with other kfree functions and consume_skb, and Eric agreed with that. Thanks, Myungho
