fbarray: fix attach deadlock

  rte_fbarray_attach() currently locks its internal
spinlock, but never releases it. Secondary processes
won't even start if there is more than one fbarray
to be attached to - the second rte_fbarray_attach()
would be just stuck.

Fix it by releasing the lock at the end of
rte_fbarray_attach(). I believe this was the original
intention.

Fixes: 5b61c62cfd76 ("fbarray: add internal tailq for mapped areas")
Cc: anatoly.burakov@intel.com
Cc: thomas@monjalon.net

Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
---
 lib/librte_eal/common/eal_common_fbarray.c | 2 ++
 1 file changed, 2 insertions(+)
  

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Darek Stojaczyk
> Sent: Friday, March 29, 2019 1:10 PM
> To: dev@dpdk.org
> Cc: james.r.harris@intel.com; changpeng.liu@intel.com; Darek Stojaczyk
> <dariusz.stojaczyk@intel.com>; anatoly.burakov@intel.com;
> thomas@monjalon.net
> Subject: [dpdk-dev] [PATCH] fbarray: fix attach deadlock
>
> rte_fbarray_attach() currently locks its internal
> spinlock, but never releases it. Secondary processes
> won't even start if there is more than one fbarray
> to be attached to - the second rte_fbarray_attach()
> would be just stuck.
>
> Fix it by releasing the lock at the end of
> rte_fbarray_attach(). I believe this was the original
> intention.
>
> Fixes: 5b61c62cfd76 ("fbarray: add internal tailq for mapped areas")
> Cc: anatoly.burakov@intel.com
> Cc: thomas@monjalon.net
>
> Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
> ---
>  lib/librte_eal/common/eal_common_fbarray.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/lib/librte_eal/common/eal_common_fbarray.c
> b/lib/librte_eal/common/eal_common_fbarray.c
> index 0e7366e5e..5ca8d6f0e 100644
> --- a/lib/librte_eal/common/eal_common_fbarray.c
> +++ b/lib/librte_eal/common/eal_common_fbarray.c
> @@ -906,6 +906,7 @@ rte_fbarray_attach(struct rte_fbarray *arr)
>
>  /* we're done */
>
> +rte_spinlock_unlock(&mem_area_lock);
>  return 0;
>  fail:
>  if (data)
> @@ -913,6 +914,7 @@ rte_fbarray_attach(struct rte_fbarray *arr)
>  if (fd >= 0)
>  close(fd);
>  free(ma);
> +rte_spinlock_unlock(&mem_area_lock);
>  return -1;
>  }

This is an obvious issue, good catch!
Reviewed-by: Gavin Hu <gavin.hu@arm.com>

> --
> 2.17.1

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