Re: [dpdk-dev] [PATCH] timer: fix resource leak in finalize

["Carrillo, Erik G" <erik.g.carrillo@intel.com>]

> -----Original Message-----
> From: Burakov, Anatoly
> Sent: Thursday, May 2, 2019 4:18 AM
> To: Carrillo, Erik G <erik.g.carrillo@intel.com>; rsanford@akamai.com;
> thomas@monjalon.net
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] timer: fix resource leak in finalize
> 
> On 01-May-19 8:00 PM, Erik Gabriel Carrillo wrote:
> > The finalize function should free the memzone created in the init
> > function, rather than freeing the allocation the memzone references,
> > otherwise a memzone descriptor can be leaked.
> >
> > Fixes: c0749f7096c7 ("timer: allow management in shared memory")
> >
> > Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
> > ---
> >   lib/librte_timer/rte_timer.c | 12 ++++++++++--
> >   1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_timer/rte_timer.c
> > b/lib/librte_timer/rte_timer.c index eb46009..fb7a87e 100644
> > --- a/lib/librte_timer/rte_timer.c
> > +++ b/lib/librte_timer/rte_timer.c
> > @@ -60,6 +60,7 @@ struct rte_timer_data {
> >   };
> >
> >   #define RTE_MAX_DATA_ELS 64
> > +static const struct rte_memzone *rte_timer_data_mz;
> >   static struct rte_timer_data *rte_timer_data_arr;
> >   static const uint32_t default_data_id;
> >   static uint32_t rte_timer_subsystem_initialized; @@ -164,6 +165,7 @@
> > rte_timer_subsystem_init_v1905(void)
> >   		if (mz == NULL)
> >   			return -EEXIST;
> >
> > +		rte_timer_data_mz = mz;
> >   		rte_timer_data_arr = mz->addr;
> >
> >   		rte_timer_data_arr[default_data_id].internal_flags |= @@ -
> 180,6
> > +182,7 @@ rte_timer_subsystem_init_v1905(void)
> >   	if (mz == NULL)
> >   		return -ENOMEM;
> >
> > +	rte_timer_data_mz = mz;
> >   	rte_timer_data_arr = mz->addr;
> >
> >   	for (i = 0; i < RTE_MAX_DATA_ELS; i++) { @@ -205,8 +208,13 @@
> > BIND_DEFAULT_SYMBOL(rte_timer_subsystem_init, _v1905, 19.05);
> >   void __rte_experimental
> >   rte_timer_subsystem_finalize(void)
> >   {
> > -	if (rte_timer_data_arr)
> > -		rte_free(rte_timer_data_arr);
> > +	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> > +		return;
> > +
> > +	if (!rte_timer_subsystem_initialized)
> > +		return;
> > +
> > +	rte_memzone_free(rte_timer_data_mz);
> 
> The patch is a correct fix, but the whole idea of this looks dangerous to me.
> 
> If we exit the primary while secondaries are still running, wouldn't it basically
> pull out timer data from under secondaries' feet?
> 

Ah yes - that’s right.  Perhaps it would be better to maintain a reference count of some sort such that the last process to exit could cause the memzone_free.

Thanks,
Erik

> >
> >   	rte_timer_subsystem_initialized = 0;
> >   }
> >
> 
> 
> --
> Thanks,
> Anatoly