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From: Andrea Parri <andrea.parri@amarulasolutions.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jorgen Hansen <jhansen@vmware.com>,
	Will Deacon <will.deacon@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [PATCH 1/2] vmw_vmci: Clean up uses of atomic*_set()
Date: Fri, 24 May 2019 13:56:12 +0200	[thread overview]
Message-ID: <20190524115612.GA21365@andrea> (raw)
In-Reply-To: <20190524103934.GO2606@hirez.programming.kicks-ass.net>

On Fri, May 24, 2019 at 12:39:34PM +0200, Peter Zijlstra wrote:
> On Fri, May 24, 2019 at 12:35:35PM +0200, Andrea Parri wrote:
> > The primitive vmci_q_set_pointer() relies on atomic*_set() being of
> > type 'void', but this is a non-portable implementation detail.
> > 
> > Reported-by: Mark Rutland <mark.rutland@arm.com>
> > Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Jorgen Hansen <jhansen@vmware.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Will Deacon <will.deacon@arm.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
> > ---
> >  include/linux/vmw_vmci_defs.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/vmw_vmci_defs.h b/include/linux/vmw_vmci_defs.h
> > index 0c06178e4985b..eb593868e2e9e 100644
> > --- a/include/linux/vmw_vmci_defs.h
> > +++ b/include/linux/vmw_vmci_defs.h
> > @@ -759,9 +759,9 @@ static inline void vmci_q_set_pointer(atomic64_t *var,
> >  				      u64 new_val)
> >  {
> >  #if defined(CONFIG_X86_32)
> > -	return atomic_set((atomic_t *)var, (u32)new_val);
> > +	atomic_set((atomic_t *)var, (u32)new_val);
> >  #else
> > -	return atomic64_set(var, new_val);
> > +	atomic64_set(var, new_val);
> >  #endif
> >  }
> 
> All that should just die a horrible death. That code is crap.
> 
> See:
> 
>   lkml.kernel.org/r/20190524103731.GN2606@hirez.programming.kicks-ass.net

I see, that was indeed 'racy' with my patch!  ;-)  Thank you!

  Andrea

  parent reply	other threads:[~2019-05-24 11:56 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24 10:35 [PATCH 0/2] Prevent evaluation of WRITE_ONCE() Andrea Parri
2019-05-24 10:35 ` [PATCH 1/2] vmw_vmci: Clean up uses of atomic*_set() Andrea Parri
2019-05-24 10:39   ` Peter Zijlstra
2019-05-24 11:40     ` Greg Kroah-Hartman
2019-05-24 11:59       ` Andrea Parri
2019-05-24 11:56     ` Andrea Parri [this message]
2019-05-24 10:35 ` [PATCH 2/2] compiler: Prevent evaluation of WRITE_ONCE() Andrea Parri
2019-05-24 10:53   ` Mark Rutland
2019-05-24 11:24     ` Andrea Parri

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