Re: [PATCH] pm/opp: fix race between opp_add and opp_get

[Viresh Kumar]

On 27-04-26, 20:00, Xuewen Yan wrote:
> From: Di Shen <di.shen@xxxxxxxxxx>
> 
> There is a race between opp_table_find_key and dev_pm_opp_add_dynamic:
> 
> dev_pm_opp_add_dynamic                dev_pm_opp_find_freq_exact
> _opp_add_v1                           _find_key
> _opp_add                              _opp_table_find_key
> mutex_lock(opp_table->lock)
> list_add(&new_opp->node, head)
> mutex_unlock(opp_table->lock)
>                                      mutex_lock(opp_table->lock)
>                                      dev_pm_opp_get(opp)
>                                      kref_get(&opp->kref)
>                                        refcount_inc(&kref->refcount);
>                                      mutex_unlock(opp_table->lock)
> kref_init(&new_opp->kref)
>   refcount_set(&kref->refcount, 1);
>                                      dev_pm_opp_put()
>                                      kref_put_mutex()
> 
> This would cause the opp be freed.
> 
> So use the mutex to protect opp's ref count.
> 
> Co-developed-by: Ling Xu <ling_ling.xu@xxxxxxxxxx>
> Signed-off-by: Ling Xu <ling_ling.xu@xxxxxxxxxx>
> Signed-off-by: Di Shen <di.shen@xxxxxxxxxx>
> ---
>  drivers/opp/core.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)

Good catch.

Applied. Thanks.

-- 
viresh