[dpdk-dev] [PATCH v3 2/4] bbdev: use C11 atomic builtins for device processing counter

[Chautru, Nicolas]

Thanks Honnappa, 

Acked-By: Nicolas Chautru <nicolas.chautru at intel.com>

> -----Original Message-----
> From: Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>
> Sent: Thursday, September 24, 2020 3:45 PM
> To: Chautru, Nicolas <nicolas.chautru at intel.com>; Phil Yang
> <Phil.Yang at arm.com>; dev at dpdk.org; david.marchand at redhat.com; Hunt,
> David <david.hunt at intel.com>
> Cc: Ruifeng Wang <Ruifeng.Wang at arm.com>; nd <nd at arm.com>;
> Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>; nd
> <nd at arm.com>
> Subject: RE: [PATCH v3 2/4] bbdev: use C11 atomic builtins for device
> processing counter
> 
> <snip>
> 
> >
> > Hi Phil,
> > Naïve question but the deprecation document was stating that "DPDK
> > will adopt C11 atomic operations semantics and provide wrappers using
> > C11 atomic built-ins."
> At the time of writing the deprecation notice, that was the thinking.
> However, through further discussions [1] in the community, it was decided
> to use atomic built-ins.
> 
> [1] http://mails.dpdk.org/archives/dev/2020-May/167416.html
> 
> > Here you are using directly the C11 atomic built-ins and not providing
> > and using a DPDK wrapper.
> > Wasn't the intent to have a new rte_... wrapper here? Ie. the same way
> > as the __sync_fetch_and_add() were called before behind the
> > rte_atomicNN_XX wrapper.
> >
> > Thanks
> > Nic
> >
> >
> > > -----Original Message-----
> > > From: Phil Yang <phil.yang at arm.com>
> > > Sent: Wednesday, September 23, 2020 10:39 PM
> > > To: dev at dpdk.org; david.marchand at redhat.com; Chautru, Nicolas
> > > <nicolas.chautru at intel.com>; Hunt, David <david.hunt at intel.com>
> > > Cc: Ruifeng.Wang at arm.com; Honnappa.Nagarahalli at arm.com;
> > nd at arm.com
> > > Subject: [PATCH v3 2/4] bbdev: use C11 atomic builtins for device
> > > processing counter
> > >
> > > Since rte_atomicXX APIs are not allowed to be used, use C11 atomic
> > > builtins for device processing counter.
> > >
> > > Signed-off-by: Phil Yang <phil.yang at arm.com>
> > > Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> > > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> > > ---
> > >  lib/librte_bbdev/rte_bbdev.c | 5 +++--
> > > lib/librte_bbdev/rte_bbdev.h
> > > | 4 +---
> > >  2 files changed, 4 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/lib/librte_bbdev/rte_bbdev.c
> > > b/lib/librte_bbdev/rte_bbdev.c index a4fdb69..5ba891c 100644
> > > --- a/lib/librte_bbdev/rte_bbdev.c
> > > +++ b/lib/librte_bbdev/rte_bbdev.c
> > > @@ -210,7 +210,7 @@ rte_bbdev_allocate(const char *name)
> > >  		return NULL;
> > >  	}
> > >
> > > -	rte_atomic16_inc(&bbdev->data->process_cnt);
> > > +	__atomic_add_fetch(&bbdev->data->process_cnt, 1,
> > > __ATOMIC_RELAXED);
> > >  	bbdev->data->dev_id = dev_id;
> > >  	bbdev->state = RTE_BBDEV_INITIALIZED;
> > >
> > > @@ -252,7 +252,8 @@ rte_bbdev_release(struct rte_bbdev *bbdev)
> > >  	}
> > >
> > >  	/* clear shared BBDev Data if no process is using the device
> > > anymore */
> > > -	if (rte_atomic16_dec_and_test(&bbdev->data->process_cnt))
> > > +	if (__atomic_sub_fetch(&bbdev->data->process_cnt, 1,
> > > +			      __ATOMIC_RELAXED) == 0)
> > >  		memset(bbdev->data, 0, sizeof(*bbdev->data));
> > >
> > >  	memset(bbdev, 0, sizeof(*bbdev));
> > > diff --git a/lib/librte_bbdev/rte_bbdev.h
> > > b/lib/librte_bbdev/rte_bbdev.h index 5729137..7017124 100644
> > > --- a/lib/librte_bbdev/rte_bbdev.h
> > > +++ b/lib/librte_bbdev/rte_bbdev.h
> > > @@ -33,7 +33,6 @@ extern "C" {
> > >  #include <string.h>
> > >
> > >  #include <rte_compat.h>
> > > -#include <rte_atomic.h>
> > >  #include <rte_bus.h>
> > >  #include <rte_cpuflags.h>
> > >  #include <rte_memory.h>
> > > @@ -426,8 +425,7 @@ struct rte_bbdev_data {
> > >  	uint16_t dev_id;  /**< Device ID */
> > >  	int socket_id;  /**< NUMA socket that device is on */
> > >  	bool started;  /**< Device run-time state */
> > > -	/** Counter of processes using the device */
> > > -	rte_atomic16_t process_cnt;
> > > +	uint16_t process_cnt;  /** Counter of processes using the device
> > > +*/
> > >  };
> > >
> > >  /* Forward declarations */
> > > --
> > > 2.7.4