On Friday 19 February 2016 10:48:30 Murali Karicheri wrote:
> On 02/19/2016 09:41 AM, Arnd Bergmann wrote:
> > On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
> >> From: Arnd Bergmann <a...@arndb.de>
> >>
> >> The commit 899077791403 ("netcp: try to reduce type confusion in
> >> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
> >> get/set_pad_info() functionality.
> >>
> >> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
> >> store DMA/MEM buffer pointer and buffer size respectively. And in both
> >> cases for Keystone 2 the pointer type size is 32 bit regardless of
> >> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
> >> is not expected to be defined.
> >>
> >> !LAPE LPAE
> >> sizeof(void*) 32bit 32bit
> >> sizeof(dma_addr_t) 32bit 32bit
> >> sizeof(phys_addr_t) 32bit 64bit
> >
> > As this was never relevant or true, I don't think it needs to be
> > mentioned here, it just confuses things. Please just assume that
> > dma_addr_t can be 64-bit wide, but will only contain 32-bit
> > numbers on keystone.
> >
>
> I can remove this from the commit description and re-send.
Ok
> >> Unfortunately, above commit changed buffer's pointers save/restore
> >> code (get/set_pad_info()) and added intermediate conversation to u64
> >> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
> >> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
> >> exception. This issue was reported and discussed in [1].
> >
> > Have you been able to figure out why it actually broke? I'd still
> > like to know.
> >
> As Grygorii is out of office until Monday, I would like to step in.
> I will take some time today to try review the reverted changes for
> failure reason and get back. But as you have agreed in the discussion
> at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
> Can we fix the regression by applying this patch and rest of the series
> if it looks good? If I need to separate this from rest of the series,
> let me know and I can take care of that.
Yes, sounds fine.
> >> Hence, fix it by partially reverting above commit and restoring
> >> get/set_pad_info() functionality as it was before.
> >>
> >> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
> >> Cc: Wingman Kwok <w-kw...@ti.com>
> >> Cc: Mugunthan V N <mugunthan...@ti.com>
> >> CC: David Laight <david.lai...@aculab.com>
> >> Reported-by: Franklin S Cooper Jr <fcoo...@ti.com>
> >> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> >> Signed-off-by: Grygorii Strashko <grygorii.stras...@ti.com>
> >> Signed-off-by: Murali Karicheri <m-kariche...@ti.com>
> >
> > I don't think I sent this patch with a 'Signed-off-by', did I?
> > (I could be misremembering that).
> >
>
> I think you had agreed based on what I read at
> https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
>
> reproduced below for your convenience.
> =============================================================================
>
> > What I could do now is update your/my patch as i mentioned in [1]
> > and re-send it at the weekend (with your authorship and my signoff).
> > Do you agree?
> >
> >
> > [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html
>
> Yes, let's do that in the meantime. I can also make sure that that
> the driver doesn't build on 64-bit, just in case.
> =============================================================================
>
> Hope I can keep your sign-off when I re-send this. Please confirm.
The most important part here is that you don't add a "Signed-off-by"
tag unless it was provided by that person as part of the submission.
I'm slightly uncomfortable with having my Signed-off-by as the first
one when I did not write the changelog myself, so I'd prefer if
you just add my Acked-by once I provide that. If that doesn't
work for you, let's follow up in private to sort it out.
Arnd
