From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH] base: dd: don't remove driver_data in -EPROBE_DEFER case Date: Tue, 3 May 2016 08:07:39 -0700 Message-ID: <20160503150739.GA14897@kroah.com> References: <1457450122-5792-1-git-send-email-yizhang_hust@163.com> <20160503131126.GA18494@ulmo.ba.sec> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160503131126.GA18494-EkSeR96xj6Pcmrwk2tT4+A@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Yi Zhang , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Tue, May 03, 2016 at 03:11:26PM +0200, Thierry Reding wrote: > On Tue, Mar 08, 2016 at 11:15:22PM +0800, Yi Zhang wrote: > > the driver_data may be used for sanity check, it fails the > > probe() if driver_data is NULL after it is re-triggered. > > for example, soc_probe() in sound/soc/soc-core.c > > > > Signed-off-by: Yi Zhang > > --- > > drivers/base/dd.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > Hi Greg, > > This causes a boot regression on at least one board, caused by one of > the drivers looking at driver data to check whether or not the driver > has properly loaded. If the code encounters a non-NULL pointer it > tries to dereference it, but because it's already been freed there is > no memory backing it and things crash. > > I don't think keeping stale pointers around is a good idea. The whole > point of setting this to NULL in the core is so that probe failures > result in the same starting conditions no matter what. > > Can we please get this reverted? > > Cc'ing linux-tegra for visibility since that's where the boot regression > is observed. Now reverted, thanks for letting me know. greg k-h