Re: [PATCH 2/2] [media] ddbridge: don't break on single/last port attach failure

[Mauro Carvalho Chehab <mchehab@kernel.org>]

Em Wed, 13 Dec 2017 18:40:52 +0100
Daniel Scheller <d.scheller.oss@gmail.com> escreveu:

> On Wed, 13 Dec 2017 13:26:02 -0200
> Mauro Carvalho Chehab <mchehab@kernel.org> wrote:
> 
> > Em Wed,  6 Dec 2017 18:59:15 +0100
> > Daniel Scheller <d.scheller.oss@gmail.com> escreveu:
> >   
> > > From: Daniel Scheller <d.scheller@gmx.net>
> > > 
> > > As all error handling improved quite a bit, don't stop attaching
> > > frontends if one of them failed, since - if other tuner modules are
> > > connected to the PCIe bridge - other hardware may just work, so
> > > lets not break on a single port failure, but rather initialise as
> > > much as possible. Ie. if there are issues with a C2T2-equipped PCIe
> > > bridge card which has additional DuoFlex modules connected and the
> > > bridge generally works, the DuoFlex tuners can still work fine.
> > > Also, this only had an effect anyway if the failed device/port was
> > > the last one being enumerated.
> > > 
> > > Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
> > > ---
> > >  drivers/media/pci/ddbridge/ddbridge-core.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/media/pci/ddbridge/ddbridge-core.c
> > > b/drivers/media/pci/ddbridge/ddbridge-core.c index
> > > 11c5cae92408..b43c40e0bf73 100644 ---
> > > a/drivers/media/pci/ddbridge/ddbridge-core.c +++
> > > b/drivers/media/pci/ddbridge/ddbridge-core.c @@ -1962,7 +1962,7 @@
> > > int ddb_ports_attach(struct ddb *dev) }
> > >  	for (i = 0; i < dev->port_num; i++) {
> > >  		port = &dev->port[i];
> > > -		ret = ddb_port_attach(port);
> > > +		ddb_port_attach(port);    
> > 
> > Nah, ignoring an error doesn't seem right. It should at least print
> > that attach failed.  
> 
> This is already the case in ddb_port_attach() (if (ret < 0)
> dev_err(...)).
> 
> > Also, if all attaches fail, probably the best
> > would be to just detach everything and go to the error handling code,
> > as there's something serious happening.  
> 
> Well, will recheck the whole error handling there then when already at
> it, as single port failures can still leave some half-initialised stuff
> behind until ddbridge gets unloaded.

If this is the case, then you need to fix also the unbind logic,
to be sure that nothing gets left. The best is to compile your test
Kernel with KASAN enabled, in order to see if the remove logic is
OK.

> 
> Thanks for your review, comments and your proposal!
> 
> Best regards,
> Daniel Scheller



Thanks,
Mauro