Re: [PATCH RESEND] h8300: fix syscall restarting

[Mark Rutland <mark.rutland@arm.com>]

On Mon, Oct 17, 2016 at 10:04:32AM -0700, Andy Lutomirski wrote:
> On Mon, Oct 17, 2016 at 7:35 AM, Mark Rutland <mark.rutland@arm.com> wrote:
> > Back in commit f56141e3e2d9aabf ("all arches, signal: move restart_block
> > to struct task_struct"), all architectures and core code were changed to
> > use task_struct::restart_block. However, when h8300 support was
> > subsequently restored in v4.2, it was not updated to account for this,
> > and maintains thread_info::restart_block, which is not kept in sync.
> >
> > This patch drops the redundant restart_block from thread_info, and moves
> > h8300 to the common one in task_struct, ensuring that syscall restarting
> > always works as expected.
> 
> This is Obviously Correct (tm). Should it have a cc: stable?

> > Cc: stable@vger.kernel.org # v4.2+

Yes. ;)

I must've messed up with git-send-email for the "real" Cc list.

Thanks,
Mark.

> > Cc: uclinux-h8-devel@lists.sourceforge.jp
> > ---
> >  arch/h8300/include/asm/thread_info.h | 4 ----
> >  arch/h8300/kernel/signal.c           | 2 +-
> >  2 files changed, 1 insertion(+), 5 deletions(-)
> >
> > This was previously sent as a reply to another patch [1], and then subsequently
> > on its own [2], but I haven't heard anything for about three weeks since the
> > last posting.
> >
> > This happens to get in the way of moving thread_info into task_struct on some
> > architectures as it implicitly relies on include ordering in a core header. I
> > have a workaround for that, but this does seem like a major bug regardless...
> >
> > Mark.
> >
> > [1] http://lkml.kernel.org/r/20160919104254.GA12473@leverpostej
> > [2] http://lkml.kernel.org/r/1474918434-3870-1-git-send-email-mark.rutland@arm.com
> >
> > diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h
> > index b408fe6..3cef068 100644
> > --- a/arch/h8300/include/asm/thread_info.h
> > +++ b/arch/h8300/include/asm/thread_info.h
> > @@ -31,7 +31,6 @@ struct thread_info {
> >         int                cpu;                 /* cpu we're on */
> >         int                preempt_count;       /* 0 => preemptable, <0 => BUG */
> >         mm_segment_t            addr_limit;
> > -       struct restart_block restart_block;
> >  };
> >
> >  /*
> > @@ -44,9 +43,6 @@ struct thread_info {
> >         .cpu =          0,                      \
> >         .preempt_count = INIT_PREEMPT_COUNT,    \
> >         .addr_limit     = KERNEL_DS,            \
> > -       .restart_block  = {                     \
> > -               .fn = do_no_restart_syscall,    \
> > -       },                                      \
> >  }
> >
> >  #define init_thread_info       (init_thread_union.thread_info)
> > diff --git a/arch/h8300/kernel/signal.c b/arch/h8300/kernel/signal.c
> > index ad1f81f..7138303 100644
> > --- a/arch/h8300/kernel/signal.c
> > +++ b/arch/h8300/kernel/signal.c
> > @@ -79,7 +79,7 @@ struct rt_sigframe {
> >         unsigned int er0;
> >
> >         /* Always make any pending restarted system calls return -EINTR */
> > -       current_thread_info()->restart_block.fn = do_no_restart_syscall;
> > +       current->restart_block.fn = do_no_restart_syscall;
> >
> >         /* restore passed registers */
> >  #define COPY(r)  do { err |= get_user(regs->r, &usc->sc_##r); } while (0)
> > --
> > 1.9.1
> >
> 
> -- 
> Andy Lutomirski
> AMA Capital Management, LLC
>