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

[Honnappa Nagarahalli]

<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