From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Alastair D'Silva <alastair@au1.ibm.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Paul Mackerras <paulus@samba.org>,
alastair@d-silva.org, Thomas Gleixner <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org,
Allison Randal <allison@lohutok.net>
Subject: Re: [PATCH] powerpc: Allow flush_(inval_)dcache_range to work across ranges >4GB
Date: Tue, 20 Aug 2019 09:30:17 -0700 [thread overview]
Message-ID: <20190820163017.GG8214@kroah.com> (raw)
In-Reply-To: <20190816071412.GF1368@kroah.com>
On Fri, Aug 16, 2019 at 09:14:12AM +0200, Greg Kroah-Hartman wrote:
> On Fri, Aug 16, 2019 at 11:42:22AM +1000, Michael Ellerman wrote:
> > Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
> > > On Thu, Aug 15, 2019 at 02:55:42PM +1000, Alastair D'Silva wrote:
> > >> From: Alastair D'Silva <alastair@d-silva.org>
> > >>
> > >> Heads Up: This patch cannot be submitted to Linus's tree, as the affected
> > >> assembler functions have already been converted to C.
> >
> > That was done in upstream commit:
> >
> > 22e9c88d486a ("powerpc/64: reuse PPC32 static inline flush_dcache_range()")
> >
> > Which is a larger change that we don't want to backport. This patch is a
> > minimal fix for stable trees.
> >
> >
> > >> When calling flush_(inval_)dcache_range with a size >4GB, we were masking
> > >> off the upper 32 bits, so we would incorrectly flush a range smaller
> > >> than intended.
> > >>
> > >> This patch replaces the 32 bit shifts with 64 bit ones, so that
> > >> the full size is accounted for.
> > >>
> > >> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > >> ---
> > >> arch/powerpc/kernel/misc_64.S | 4 ++--
> > >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > Acked-by: Michael Ellerman <mpe@ellerman.id.au>
> >
> > > <formletter>
> > >
> > > This is not the correct way to submit patches for inclusion in the
> > > stable kernel tree. Please read:
> > > https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> > > for how to do this properly.
> > >
> > > </formletter>
> >
> > Hi Greg,
> >
> > This is "option 3", submit the patch directly, and the patch "deviates
> > from the original upstream patch" because the upstream patch was a
> > wholesale conversion from asm to C.
> >
> > This patch applies cleanly to v4.14 and v4.19.
> >
> > The change log should have mentioned which upstream patch it is not a
> > backport of, is there anything else we should have done differently to
> > avoid the formletter bot :)
>
> That is exactly what you should have done. It needs to be VERY explicit
> as to why this is being submitted different from what upstream did, and
> to what trees it needs to go to and who is going to be responsible for
> when it breaks. And it will break :)
And it needs to be done before I can apply it, I've dropped this thread
from my queue now.
thanks,
greg k-h
prev parent reply other threads:[~2019-08-20 16:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-15 4:55 [PATCH] powerpc: Allow flush_(inval_)dcache_range to work across ranges >4GB Alastair D'Silva
2019-08-15 7:19 ` Greg Kroah-Hartman
2019-08-16 1:42 ` Michael Ellerman
2019-08-16 7:14 ` Greg Kroah-Hartman
2019-08-20 16:30 ` Greg Kroah-Hartman [this message]
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