Re: [dpdk-dev] [PATCH 1/2] librte_ethdev: Introduce a function to release HW rings

[Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>]

W dniu 05.05.2020 o 19:25, Renata Saiakhova pisze:
> Hi Lukasz,
>
> thanks for your comments! I understand Anatoly is going to to make a 
> fix rather in memzone API level, to introduce atomic "find and 
> allocate" and "find and free" operations, so this patch code won't 
> stay long and in this case maybe better not to disturb the original 
> code of rte_eth_dma_zone_reserve() ? Just a question.
I don't know. It's up to Anatoly, I guess. But your patch probably will 
be required also. You will just need to use some atomic rte_memzone_... 
function to avoid race, the function that Anatoly will propose.
>
> Kind regards,
> Renata
> ------------------------------------------------------------------------
> *From:* Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
> *Sent:* Tuesday, May 5, 2020 5:47 PM
> *To:* Renata Saiakhova <renata.saiakhova@ekinops.com>; dev@dpdk.org 
> <dev@dpdk.org>
> *Subject:* Re: [dpdk-dev] [PATCH 1/2] librte_ethdev: Introduce a 
> function to release HW rings
> Hi Renata,
>
> few minor hints inline
>
> W dniu 03.05.2020 o 18:26, Renata Saiakhova pisze:
> > Free previously allocated memzone for HW rings
> >
> > Signed-off-by: Renata Saiakhova <Renata.Saiakhova@ekinops.com>
> > ---
> >   lib/librte_ethdev/rte_ethdev.c           | 23 +++++++++++++++++++++++
> >   lib/librte_ethdev/rte_ethdev_driver.h    | 14 ++++++++++++++
> >   lib/librte_ethdev/rte_ethdev_version.map |  1 +
> >   3 files changed, 38 insertions(+)
> >
> > diff --git a/lib/librte_ethdev/rte_ethdev.c 
> b/lib/librte_ethdev/rte_ethdev.c
> > index 72aed59a5..c6d27e1aa 100644
> > --- a/lib/librte_ethdev/rte_ethdev.c
> > +++ b/lib/librte_ethdev/rte_ethdev.c
> > @@ -4206,6 +4206,29 @@ rte_eth_dma_zone_reserve(const struct 
> rte_eth_dev *dev, const char *ring_name,
> >                        RTE_MEMZONE_IOVA_CONTIG, align);
> >   }
> >
> > +int
> > +rte_eth_dma_zone_free(const struct rte_eth_dev *dev, const char 
> *ring_name,
> > +             uint16_t queue_id)
> > +{
> > +     char z_name[RTE_MEMZONE_NAMESIZE];
> > +     const struct rte_memzone *mz;
> > +     int rc = 0;
> > +
> > +     snprintf(z_name, sizeof(z_name), "eth_p%d_q%d_%s",
> > +                     dev->data->port_id, queue_id, ring_name);
>
> probably rc=snprintf(...)
>
> but maybe create a macro for that fancy memzone name as the same code
> appears already in rte_eth_dma_zone_reserve and keeping it in one place
> seems to be better idea to me.
>
> > +     if (rc >= RTE_MEMZONE_NAMESIZE) {
> > +             RTE_ETHDEV_LOG(ERR, "ring name too long\n");
> > +             rte_errno = ENAMETOOLONG;
> > +             return NULL;
> It's an int returning function so instead of setting rte_errno, just:
>      return -ENAMETOOLONG;
> > +     }
> > +
> > +     mz = rte_memzone_lookup(z_name);
> > +     if (mz)
> > +             rc = rte_memzone_free(mz);
> > +
> > +     return rc;
> > +}
> > +
> >   int
> >   rte_eth_dev_create(struct rte_device *device, const char *name,
> >        size_t priv_data_size,
> > diff --git a/lib/librte_ethdev/rte_ethdev_driver.h 
> b/lib/librte_ethdev/rte_ethdev_driver.h
> > index 99d4cd6cd..2769a185b 100644
> > --- a/lib/librte_ethdev/rte_ethdev_driver.h
> > +++ b/lib/librte_ethdev/rte_ethdev_driver.h
> > @@ -180,6 +180,20 @@ rte_eth_dma_zone_reserve(const struct 
> rte_eth_dev *eth_dev, const char *name,
> >                         uint16_t queue_id, size_t size,
> >                         unsigned align, int socket_id);
> >
> > +/**
> > + * Free previously allocated memzone for HW rings.
> > + *
> > + * @param eth_dev
> > + *   The *eth_dev* pointer is the address of the *rte_eth_dev* 
> structure
> param name is dev
> > + * @param name
> > + *   The name of the memory zone
> param name is ring_name
> > + * @param queue_id
> > + *   The index of the queue to add to name
> > + * @param size
> There is no size param, but some info about return would be probably nice:
>   * @return
> *   Negative errno value on error, 0 on success.
>
>
> And as it's a new API function maybe it should be experimental. Should it?
>
> > + */
> > +int rte_eth_dma_zone_free(const struct rte_eth_dev *dev, const char 
> *ring_name,
> > +              uint16_t queue_id);
> > +
> >   /**
> >    * @internal
> >    * Atomically set the link status for the specific device.
> > diff --git a/lib/librte_ethdev/rte_ethdev_version.map 
> b/lib/librte_ethdev/rte_ethdev_version.map
> > index 715505604..5d3c209bc 100644
> > --- a/lib/librte_ethdev/rte_ethdev_version.map
> > +++ b/lib/librte_ethdev/rte_ethdev_version.map
> > @@ -82,6 +82,7 @@ DPDK_20.0 {
> >        rte_eth_dev_vlan_filter;
> >        rte_eth_devices;
> >        rte_eth_dma_zone_reserve;
> > +     rte_eth_dma_zone_free;
> >        rte_eth_find_next;
> >        rte_eth_find_next_owned_by;
> >        rte_eth_iterator_cleanup;
>
> Best regards
>
> Lukasz
>
> -- 
>
> Lukasz Wojciechowski
> Principal Software Engineer
>
> Samsung R&D Institute Poland
> Samsung Electronics
> Office +48 22 377 88 25
> l.wojciechow@partner.samsung.com
>
-- 

Lukasz Wojciechowski
Principal Software Engineer

Samsung R&D Institute Poland
Samsung Electronics
Office +48 22 377 88 25
l.wojciechow@partner.samsung.com