Re: [PATCH] powerpc: Clean up tm_abort duplication in hash_utils_64.c

[Rui Teng]

On 9/1/16 11:46 PM, Thiago Jung Bauermann wrote:
> Am Freitag, 26 August 2016, 11:50:10 schrieb Rui Teng:
> > The same logic appears twice and should probably be pulled out into a
> > function.
> >
> > Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Signed-off-by: Rui Teng <rui.teng@xxxxxxxxxxxxxxxxxx>
> > ---
> >  arch/powerpc/mm/hash_utils_64.c | 45
> > +++++++++++++++++------------------------ 1 file changed, 19
> > insertions(+), 26 deletions(-)
> >
> > diff --git a/arch/powerpc/mm/hash_utils_64.c
> > b/arch/powerpc/mm/hash_utils_64.c index 0821556..69ef702 100644
> > --- a/arch/powerpc/mm/hash_utils_64.c
> > +++ b/arch/powerpc/mm/hash_utils_64.c
> > @@ -1460,6 +1460,23 @@ out_exit:
> >  	local_irq_restore(flags);
> >  }
> >
> > +/*
> > + * Transactions are not aborted by tlbiel, only tlbie.
> > + * Without, syncing a page back to a block device w/ PIO could pick up
> > + * transactional data (bad!) so we force an abort here.  Before the
> > + * sync the page will be made read-only, which will flush_hash_page.
> > + * BIG ISSUE here: if the kernel uses a page from userspace without
> > + * unmapping it first, it may see the speculated version.
> > + */
> > +void local_tm_abort(int local)
> > +{
> > +	if (local && cpu_has_feature(CPU_FTR_TM) && current->thread.regs &&
> > +		MSR_TM_ACTIVE(current->thread.regs->msr)) {
> > +		tm_enable();
> > +		tm_abort(TM_CAUSE_TLBI);
> > +	}
> > +}
> > +
>
> Since local_tm_abort is only used in this file, it should be static.
OK
> Also, since both places calling it are guarded by
> CONFIG_PPC_TRANSACTIONAL_MEM, wouldn't it be cleaner if the #ifdef was here
> instead and the #else block defined an empty static inline function? Then
> the call sites wouldn't need to be guarded.
I have considered this style before, but I am worried about the call
stacks increased by empty function and forgot the inline function.
Will send v2 with your comments.

Thanks!

>