Re: [Qemu-devel] [PATCH] tcg: Initialize return value after exit_atomic

[Richard Henderson]

On 04/25/2017 01:21 PM, Nikunj A Dadhania wrote:
> Richard Henderson <address@hidden> writes:
>
> > Users of tcg_gen_atomic_cmpxchg and do_atomic_op rightfully utilize
> > the output.  Even though this code is dead, it gets translated, and
> > without the initialization we encounter a tcg_error.
> >
> > Reported-by: Nikunj A Dadhania <address@hidden>
> > Signed-off-by: Richard Henderson <address@hidden>
>
> With this the tcg_error goes away.
>
> But then powernv skiboot code [1] enters into infinite loop. Basically,
> in target/ppc/translate.c:gen_conditional_store(), setcond_tl will
> always fail, and CRF_EQ_BIT will never be set, the lock will never be
> taken.

The setcond_tl *shouldn't* always fail.  If that's the case, then we have 
another bug in the !parallel_cpus code path for gen_conditional_store.


r~