Re: [PATCH] scsi: target: tcmu: fix size in calls to tcmu_flush_dcache_range

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On Fri, Aug 28, 2020 at 12:03:38PM +0200, Bodo Stroesser wrote:
> Hi,
> I'm adding stable@xxxxxxxxxxxxxxx
> 
> Once again, this time really adding stable.
> 
> On 2020-06-03 04:31, Martin K. Petersen wrote:
> > On Thu, 28 May 2020 21:31:08 +0200, Bodo Stroesser wrote:
> > 
> > > 1) If remaining ring space before the end of the ring is
> > >      smaller then the next cmd to write, tcmu writes a padding
> > >      entry which fills the remaining space at the end of the
> > >      ring.
> > >      Then tcmu calls tcmu_flush_dcache_range() with the size
> > >      of struct tcmu_cmd_entry as data length to flush.
> > >      If the space filled by the padding was smaller then
> > >      tcmu_cmd_entry, tcmu_flush_dcache_range() is called for
> > >      an address range reaching behind the end of the vmalloc'ed
> > >      ring.
> > >      tcmu_flush_dcache_range() in a loop calls
> > >         flush_dcache_page(virt_to_page(start));
> > >      for every page being part of the range. On x86 the line is
> > >      optimized out by the compiler, as flush_dcache_page() is
> > >      empty on x86.
> > >      But I assume the above can cause trouble on other
> > >      architectures that really have a flush_dcache_page().
> > >      For paddings only the header part of an entry is relevant
> > >      Due to alignment rules the header always fits in the
> > >      remaining space, if padding is needed.
> > >      So tcmu_flush_dcache_range() can safely be called with
> > >      sizeof(entry->hdr) as the length here.
> > > 
> > > [...]
> > 
> > Applied to 5.8/scsi-queue, thanks!
> > 
> > [1/1] scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range
> >         https://git.kernel.org/mkp/scsi/c/8c4e0f212398
> > 
> 
> The full commit of this patch is:
>      8c4e0f212398cdd1eb4310a5981d06a723cdd24f
> 
> This patch is the first of four patches that are necessary to run tcmu
> on ARM without crash. For details please see
>      https://bugzilla.kernel.org/show_bug.cgi?id=208045
> Upsteam commits of patches 2,3, and 4 are:
>    2: 3c58f737231e "scsi: target: tcmu: Optimize use of flush_dcache_page"
>    3: 3145550a7f8b "scsi: target: tcmu: Fix crash in tcmu_flush_dcache_range
> on ARM"
>    4: 5a0c256d96f0 "scsi: target: tcmu: Fix crash on ARM during cmd
> completion"
> 
> Since patches 3 and 4 already were accepted for 5.8, 5.4, and 4.19, and
> I sent a request to add patch 2 about 1 hour ago, please consider adding
> this patch to 5.4 and 4.19, because without it tcmu on ARM will still
> crash.

I don't see such a request, and am confused now.

What exact commits do you want backported, and to what trees?

thanks,

greg k-h



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