Re: [PATCH v13 1/8] parisc: Drop parisc special case for __sighandler_t

From: Catalin Marinas <catalin.marinas@arm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Peter Collingbourne <pcc@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Kostya Serebryany <kcc@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Dave Martin <Dave.Martin@arm.com>, Will Deacon <will@kernel.org>,
	Oleg Nesterov <oleg@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Richard Henderson <rth@twiddle.net>,
	linux-api@vger.kernel.org, Helge Deller <deller@gmx.de>,
	David Spickett <david.spickett@linaro.org>
Subject: Re: [PATCH v13 1/8] parisc: Drop parisc special case for __sighandler_t
Date: Wed, 4 Nov 2020 17:24:48 +0000	[thread overview]
Message-ID: <20201104172447.GF28902@gaia> (raw)
In-Reply-To: <87a6vx6p11.fsf@x220.int.ebiederm.org>

On Wed, Nov 04, 2020 at 10:54:34AM -0600, Eric W. Biederman wrote:
> Peter Collingbourne <pcc@google.com> writes:
> > From: Helge Deller <deller@gmx.de>
> >
> > I believe we can and *should* drop this parisc-specific typedef for
> > __sighandler_t when compiling a 64-bit kernel. The reasons:
> >
> > 1. We don't have a 64-bit userspace yet, so nothing (on userspace side)
> > can break.
> >
> > 2. Inside the Linux kernel, this is only used in kernel/signal.c, in
> > function kernel_sigaction() where the signal handler is compared against
> > SIG_IGN.  SIG_IGN is defined as (__sighandler_t)1), so only the pointers
> > are compared.
> >
> > 3. Even when a 64-bit userspace gets added at some point, I think
> > __sighandler_t should be defined what it is: a function pointer struct.
> >
> > I compiled kernel/signal.c with and without the patch, and the produced code
> > is identical in both cases.
> >
> > Signed-off-by: Helge Deller <deller@gmx.de>
> > Reviewed-by: Peter Collingbourne <pcc@google.com>
> > Link:
> > https://linux-review.googlesource.com/id/I21c43f21b264f339e3aa395626af838646f62d97
> 
> Peter as you have sent this, this also needs your Signed-off-by.
> 
> Otherwise this looks reasonable to me.
> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> While the final bits look like they are still under discussion it looks
> like the preceding cleanups are pretty solid at this point.

Minor nits, unless you nak the whole approach of SA_FAULTFLAGS and
SA_UNSUPPORTED ;) (it looks a bit complicated to me but I don't have a
better idea for a generic implementation).

> Any chance we can get the cleanups into a tree in linux-next so that
> the discussion can focus on the core parts of this work?
> 
> Perhaps I should pick up the clenaups?

However you prefer (I usually start queuing patches at -rc3). If you
pick them up, please provide a stable branch somewhere so that we can
add the others on top.

Thanks.

-- 
Catalin