[dpdk-dev] [PATCH v2 1/4] eal: use C11 atomic builtins for already initialized check

[Phil Yang]

David Marchand <david.marchand at redhat.com> writes:

> Subject: Re: [PATCH v2 1/4] eal: use C11 atomic builtins for already initialized
> check
> 
> On Wed, Sep 16, 2020 at 10:24 AM Phil Yang <phil.yang at arm.com> wrote:
> >
> > Since rte_atomicXX APIs are not allowed to be used, use C11 builtins to
> > check if EAL is already initialized.
> >
> > Signed-off-by: Phil Yang <phil.yang at arm.com>
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> > ---
> >  lib/librte_eal/freebsd/eal.c | 18 ++++++++++--------
> >  lib/librte_eal/linux/eal.c   | 20 +++++++++++---------
> >  2 files changed, 21 insertions(+), 17 deletions(-)
> >
> > diff --git a/lib/librte_eal/freebsd/eal.c b/lib/librte_eal/freebsd/eal.c
> > index 798add0..9f4c7bb 100644
> > --- a/lib/librte_eal/freebsd/eal.c
> > +++ b/lib/librte_eal/freebsd/eal.c
> > @@ -665,7 +665,8 @@ rte_eal_init(int argc, char **argv)
> >  {
> >         int i, fctret, ret;
> >         pthread_t thread_id;
> > -       static rte_atomic32_t run_once = RTE_ATOMIC32_INIT(0);
> > +       static uint32_t run_once;
> > +       uint32_t has_run = 0;
> >         char cpuset[RTE_CPU_AFFINITY_STR_LEN];
> >         char thread_name[RTE_MAX_THREAD_NAME_LEN];
> >         const struct rte_config *config = rte_eal_get_configuration();
> > @@ -679,7 +680,8 @@ rte_eal_init(int argc, char **argv)
> >                 return -1;
> >         }
> >
> > -       if (!rte_atomic32_test_and_set(&run_once)) {
> > +       if (!__atomic_compare_exchange_n(&run_once, &has_run, 1, 0,
> > +                                       __ATOMIC_RELAXED, __ATOMIC_RELAXED)) {
> >                 rte_eal_init_alert("already called initialization.");
> >                 rte_errno = EALREADY;
> >                 return -1;
> > @@ -705,7 +707,7 @@ rte_eal_init(int argc, char **argv)
> >         if (fctret < 0) {
> >                 rte_eal_init_alert("Invalid 'command line' arguments.");
> >                 rte_errno = EINVAL;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -715,20 +717,20 @@ rte_eal_init(int argc, char **argv)
> >         if (eal_plugins_init() < 0) {
> >                 rte_eal_init_alert("Cannot init plugins");
> >                 rte_errno = EINVAL;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> >         if (eal_trace_init() < 0) {
> >                 rte_eal_init_alert("Cannot init trace");
> >                 rte_errno = EFAULT;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> >         if (eal_option_device_parse()) {
> >                 rte_errno = ENODEV;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -762,7 +764,7 @@ rte_eal_init(int argc, char **argv)
> >         if (rte_bus_scan()) {
> >                 rte_eal_init_alert("Cannot scan the buses for devices");
> >                 rte_errno = ENODEV;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -790,7 +792,7 @@ rte_eal_init(int argc, char **argv)
> >                 if (ret < 0) {
> >                         rte_eal_init_alert("Cannot get hugepage information.");
> >                         rte_errno = EACCES;
> > -                       rte_atomic32_clear(&run_once);
> > +                       __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                         return -1;
> >                 }
> >         }
> > diff --git a/lib/librte_eal/linux/eal.c b/lib/librte_eal/linux/eal.c
> > index 0960f01..82a73ed 100644
> > --- a/lib/librte_eal/linux/eal.c
> > +++ b/lib/librte_eal/linux/eal.c
> > @@ -960,7 +960,8 @@ rte_eal_init(int argc, char **argv)
> >  {
> >         int i, fctret, ret;
> >         pthread_t thread_id;
> > -       static rte_atomic32_t run_once = RTE_ATOMIC32_INIT(0);
> > +       static uint32_t run_once;
> > +       uint32_t has_run = 0;
> >         const char *p;
> >         static char logid[PATH_MAX];
> >         char cpuset[RTE_CPU_AFFINITY_STR_LEN];
> > @@ -977,7 +978,8 @@ rte_eal_init(int argc, char **argv)
> >                 return -1;
> >         }
> >
> > -       if (!rte_atomic32_test_and_set(&run_once)) {
> > +       if (!__atomic_compare_exchange_n(&run_once, &has_run, 1, 0,
> > +                                       __ATOMIC_RELAXED, __ATOMIC_RELAXED)) {
> >                 rte_eal_init_alert("already called initialization.");
> >                 rte_errno = EALREADY;
> >                 return -1;
> > @@ -1005,14 +1007,14 @@ rte_eal_init(int argc, char **argv)
> >         if (fctret < 0) {
> >                 rte_eal_init_alert("Invalid 'command line' arguments.");
> >                 rte_errno = EINVAL;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> >         if (eal_plugins_init() < 0) {
> >                 rte_eal_init_alert("Cannot init plugins");
> >                 rte_errno = EINVAL;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -1024,7 +1026,7 @@ rte_eal_init(int argc, char **argv)
> >
> >         if (eal_option_device_parse()) {
> >                 rte_errno = ENODEV;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -1064,7 +1066,7 @@ rte_eal_init(int argc, char **argv)
> >         if (rte_bus_scan()) {
> >                 rte_eal_init_alert("Cannot scan the buses for devices");
> >                 rte_errno = ENODEV;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -1138,7 +1140,7 @@ rte_eal_init(int argc, char **argv)
> >                 if (ret < 0) {
> >                         rte_eal_init_alert("Cannot get hugepage information.");
> >                         rte_errno = EACCES;
> > -                       rte_atomic32_clear(&run_once);
> > +                       __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                         return -1;
> >                 }
> >         }
> > @@ -1162,7 +1164,7 @@ rte_eal_init(int argc, char **argv)
> >         if (rte_eal_log_init(logid, internal_conf->syslog_facility) < 0) {
> >                 rte_eal_init_alert("Cannot init logging.");
> >                 rte_errno = ENOMEM;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >
> > @@ -1170,7 +1172,7 @@ rte_eal_init(int argc, char **argv)
> >         if (rte_eal_vfio_setup() < 0) {
> >                 rte_eal_init_alert("Cannot init VFIO");
> >                 rte_errno = EAGAIN;
> > -               rte_atomic32_clear(&run_once);
> > +               __atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
> >                 return -1;
> >         }
> >  #endif
> > --
> > 2.7.4
> >
> 
> I see no reason to include rte_atomic.h in those files after this patch.
> Did I miss something?

No, it is not needed anymore. 
Will remove them.


Thanks,
Phil

> 
> 
> --
> David Marchand