RE: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init* annotations

[Varun Sethi <Varun.Sethi-KZfg59tc24xl57MIdRCFDg@public.gmane.org>]

Hi Emil,

> -----Original Message-----
> From: Sethi Varun-B16395
> Sent: Wednesday, February 11, 2015 5:00 PM
> To: 'Emil Medve'; iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org; joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org;
> jroedel-l3A5Bk7waGM@public.gmane.org
> Subject: RE: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init* annotations
> 
> Hi Emil,
> 
> > -----Original Message-----
> > From: Emil Medve [mailto:Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org]
> > Sent: Wednesday, February 11, 2015 4:37 PM
> > To: Sethi Varun-B16395; iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org;
> > joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org; jroedel-l3A5Bk7waGM@public.gmane.org
> > Subject: Re: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init*
> > annotations
> >
> > Hello Varun,
> >
> >
> > On 02/09/2015 08:26 PM, Sethi Varun-B16395 wrote:
> > > Hi Emil,
> > >
> > >
> > >> -----Original Message-----
> > >> From: Emil Medve [mailto:Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org]
> > >> Sent: Tuesday, February 10, 2015 3:17 AM
> > >> To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org; joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org;
> > >> jroedel-l3A5Bk7waGM@public.gmane.org; Sethi Varun-B16395
> > >> Subject: Re: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init*
> > >> annotations
> > >>
> > >> Hello Joerg,
> > >>
> > >>
> > >> On 01/28/2015 08:34 AM, Emil Medve wrote:
> > >>> Signed-off-by: Emil Medve <Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org>
> > >>> ---
> > >>>  drivers/iommu/fsl_pamu.c        | 12 ++++++------
> > >>>  drivers/iommu/fsl_pamu_domain.c |  2 +-
> > >>>  2 files changed, 7 insertions(+), 7 deletions(-)
> > >>
> > >> Please don't apply this patch as it's wrong. It's based on
> > >> https://git.kernel.org/cgit/linux/kernel/git/joro/iommu.git/commit/
> > >> ?h
> > >> =ppc/
> > >> pamu&id=0f1fb99b62ce226f8d818852f812c5d79071ce58
> > >> which is wrong as well and its causing semi-random crashes upon
> > >> more extensive testing. I will follow-up with details shortly
> > >
> > > Are you seeing  a crash with
> > > https://git.kernel.org/cgit/linux/kernel/git/joro/iommu.git/commit/?
> > > h=
> > > ppc/pamu&id=0f1fb99b62ce226f8d818852f812c5d79071ce58
> > > ? At, what point do you see crashes?
> >
> > platform_driver.device_driver gets added to a (platform) bus klist of
> drivers.
> > (There are also a handful of other pointers that get set to
> > fsl_of_pamu_driver) Once fsl_of_pamu_driver gets released that klist
> > becomes "corrupted" and, depending on how said memory gets re-used,
> > traversing it for any reason will end up into a crash
> >
> > Anyway, I identified easier ways to produce kernel crashes related to
> > the PAMU driver via sysfs (with or without my __init* annotation
> > patches). For example a "unbind, bind" sequence will cause a crash
> > with the driver as is in
> > v3.19
> >
> > BTW, why is the PAMU an "early" driver?
> >
> > I'll send out some patches to properly fix all these __init*
> > annotations
> Yes, the fsl_of_pamu_driver structure shouldn't be marked init data, it could
> actually corrupt the driver list. PAMU driver should initialize before the DPAA
> driver initialization also, to ensure the default DMA window is setup for all
> devices.
> 
I think that we can revert this patch, the section mismatch isn't really an issue. The pamu driver probe routine wouldn't get called during platform bus probe. 

-Varun