Re: [dpdk-dev] [PATCH v8 2/3] devtools: prevent use of rte atomic APIs in future patches

[David Marchand <david.marchand@redhat.com>]

On Thu, Jul 16, 2020 at 6:58 AM Phil Yang <phil.yang@arm.com> wrote:
>
> In order to deprecate the rte_atomic and rte_smp barrier APIs, prevent
> the patches from using these APIs in the converted modules and compilers
> __sync built-ins in all modules.

builtins* for the whole patch.


>
> The converted modules:
> lib/librte_distributor
> lib/librte_hash
> lib/librte_kni
> lib/librte_lpm
> lib/librte_rcu
> lib/librte_ring
> lib/librte_stack
> lib/librte_vhost
> lib/librte_timer
> lib/librte_ipsec
> drivers/event/octeontx
> drivers/event/octeontx2
> drivers/event/opdl
> drivers/net/bnx2x
> drivers/net/hinic
> drivers/net/hns3
> drivers/net/memif
> drivers/net/thunderx
> drivers/net/virtio
> examples/l2fwd-event
>
> On x86 the __atomic_thread_fence(__ATOMIC_SEQ_CST) is quite expensive
> for SMP case. Flag the new code which use __atomic_thread_fence API.
>
> Signed-off-by: Phil Yang <phil.yang@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
>  devtools/checkpatches.sh | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
>
> diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
> index 58021aa..fb288cf 100755
> --- a/devtools/checkpatches.sh
> +++ b/devtools/checkpatches.sh
> @@ -51,6 +51,13 @@ print_usage () {
>
>  check_forbidden_additions() { # <patch>
>         res=0
> +       c11_atomics_dir="lib/librte_distributor lib/librte_hash lib/librte_kni
> +                        lib/librte_lpm lib/librte_rcu lib/librte_ring
> +                        lib/librte_stack lib/librte_vhost
> +                        drivers/event/octeontx drivers/event/octeontx2
> +                        drivers/event/opdl drivers/net/bnx2x drivers/net/hinic
> +                        drivers/net/hns3 drivers/net/memif drivers/net/thunderx
> +                        drivers/net/virtio examples/l2fwd-event"

I prefer a form like:

+    c11_atomics_dir=""
+    c11_atomics_dir="$c11_atomics_dir drivers/event/octeontx"
+    c11_atomics_dir="$c11_atomics_dir drivers/event/octeontx2"
+    c11_atomics_dir="$c11_atomics_dir drivers/event/opdl"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/bnx2x"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/hinic"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/hns3"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/memif"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/thunderx"
+    c11_atomics_dir="$c11_atomics_dir drivers/net/virtio"
+    c11_atomics_dir="$c11_atomics_dir examples/l2fwd-event"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_distributor"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_hash"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_kni"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_lpm"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_rcu"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_ring"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_stack"
+    c11_atomics_dir="$c11_atomics_dir lib/librte_vhost"

Easier to read and update.


>
>         # refrain from new additions of rte_panic() and rte_exit()
>         # multiple folders and expressions are separated by spaces
> @@ -74,6 +81,39 @@ check_forbidden_additions() { # <patch>
>                 -v EXPRESSIONS='for[[:space:]]*\\((char|u?int|unsigned|s?size_t)' \
>                 -v RET_ON_FAIL=1 \
>                 -v MESSAGE='Declaring a variable inside for()' \

This hunk breaks the script.
This is not seen by the CI, as the CI uses its local copy of the script.

We are missing a:
+               "$1" || res=1


> +
> +       # refrain from new additions of 16/32/64 bits rte_atomic_xxx()
> +       # multiple folders and expressions are separated by spaces
> +       awk -v FOLDERS="$c11_atomics_dir" \
> +               -v EXPRESSIONS="rte_atomic[0-9][0-9]_.*\\\(" \
> +               -v RET_ON_FAIL=1 \
> +               -v MESSAGE='Use of rte_atomicNN_xxx APIs not allowed, use __atomic_xxx built-ins' \

Other messages in this script report what is wrong.
Example:
                -v MESSAGE='Using rte_panic/rte_exit' \
                -v MESSAGE='Using compiler attribute directly' \
                -v MESSAGE='Declaring a variable inside for()' \

So to be consistent,
+               -v MESSAGE='Using rte_atomicNN_xxx' \


> +               -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> +               "$1" || res=1
> +
> +       # refrain from new additions of rte_smp_XXmb()
> +       # multiple folders and expressions are separated by spaces
> +       awk -v FOLDERS="$c11_atomics_dir" \
> +               -v EXPRESSIONS="rte_smp_(r|w)?mb\\\(" \
> +               -v RET_ON_FAIL=1 \
> +               -v MESSAGE='Use of rte_smp_[r/w]mb not allowed, use __atomic_xxx built-ins' \

+               -v MESSAGE='Using rte_smp_[r/w]mb' \

> +               -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> +               "$1" || res=1
> +
> +       # refrain from using compiler __sync built-ins
> +       awk -v FOLDERS="lib drivers app examples" \
> +               -v EXPRESSIONS="__sync_.*\\\(" \
> +               -v RET_ON_FAIL=1 \
> +               -v MESSAGE='Use of __sync_xxx built-ins not allowed, use __atomic_xxx built-ins' \

+               -v MESSAGE='Using __sync_xxx builtins' \


> +               -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> +               "$1" || res=1
> +
> +       # refrain from using compiler __atomic_thread_fence()
> +       # It should be avoided on x86 for SMP case.
> +       awk -v FOLDERS="lib drivers app examples" \
> +               -v EXPRESSIONS="__atomic_thread_fence\\\(" \
> +               -v RET_ON_FAIL=1 \
> +               -v MESSAGE='The __atomic_thread_fence is not allowed, use rte_atomic_thread_fence' \

+               -v MESSAGE='Using __atomic_thread_fence' \


>                 -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
>                 "$1" || res=1
>


-- 
David Marchand