[RFC] Introduce checkpatch action

.cirrus.yml

@@ -9,7 +9,7 @@ cargo_task_tempate: &cargo_task_template
       - cat Cargo.lock
   setup_script:
     - apt-get update
-    - apt-get -y install llvm clang libelf-dev libpcap-dev python3-pip make jq
+    - apt-get -y install locales llvm clang libelf-dev libpcap-dev python3-pip make jq
     - rustup component add rustfmt
     - rustup component add clippy
   before_cache_script: rm -rf $CARGO_HOME/registry/index
@@ -20,9 +20,25 @@ unittest_task:
     image: rust:bookworm
   build_script: make V=1 CARGO_OPTS=--verbose
   test_script: make test V=1 CARGO_OPTS=--verbose
-  check_script:
+  rust_check_script:
     - cargo fmt --check
     - cargo clippy -- -D warnings
+  ebpf_style_script: |
+    # make perl happy.
+    locale-gen en_US.UTF-8
+    export LANGUAGE=en_US.UTF-8
+    git remote update origin
+    cirrus_base=$(git merge-base origin/$CIRRUS_BASE_BRANCH HEAD)
+    COMMIT_RANGE=$(git rev-list ${cirrus_base}..HEAD --reverse)
+    for commit in $COMMIT_RANGE; do
+        pretty_commit=$(git -P show -s --format="%h (\"%s\")" --abbrev=12 ${commit})
+        echo "Commit ${pretty_commit}"
+        printf -- '-%0.s' $(seq 1 ${#pretty_commit})
+        echo "-------"
+        git show --format=email ${commit} -- '*/bpf/*' | ./tools/checkpatch.pl --no-tree --ignore=SPDX_LICENSE_TAG,FILE_PATH_CHANGES,EMAIL_SUBJECT,VOLATILE -q || { restyle=1 ; true ; }
+        echo
+    done
+    [ -z "${restyle}" ]
 
 benchmark_task:
   << : *cargo_task_template

.gitattributes

@@ -1,3 +1,6 @@
 vmlinux.h linguist-vendored
 **/bpf_sys/include/linux/*.h linguist-vendored
 *_uapi.rs linguist-vendored
+tools/checkpatch.pl linguist-vendored
+tools/spelling.txt linguist-vendored
+tools/const_structs.checkpatch linguist-vendored

docs/CONTRIBUTING.md

@@ -84,12 +84,13 @@ and/or [help wanted](https://github.com/retis-org/retis/issues?q=is%3Aissue+is%3
 
 ### Coding style
 
-We strictly follow the Rust coding style as enforced by `rustfmt` and have a
-strong preference for the
-[Linux kernel](https://www.kernel.org/doc/html/latest/process/coding-style.html)
-and particularly its
+We strictly follow the Rust coding style as enforced by `rustfmt` and we also adhere the
+[Linux kernel](https://www.kernel.org/doc/html/latest/process/coding-style.html) coding style
+as enforced by `checkpatch.pl` and particularly its
 [networking](https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html#multi-line-comments)
-flavor coding style for the BPF parts.
+flavor for the BPF parts. `checkpatch.pl` can generate false
+positives, and in such case the formerly described coding style rules
+take precedence over its suggestions.
 
 ### Events and Rust bindings
 

retis/src/core/filters/packets/bpf/include/packet_filter.h

@@ -56,10 +56,11 @@ unsigned int packet_filter(struct retis_packet_filter_ctx *ctx, u32 placeholder)
 	u8 stack[STACK_SIZE] __attribute__ ((aligned (8)));
 	register u64 *fp asm("r9");
 
-	if (!ctx)
+	if (!ctx) {
 		return 0;
+	}
 
-	ctx_reg = ctx;
+   ctx_reg = ctx;
 	fp = (u64 *)((void *)stack + sizeof(stack));
 
 	asm volatile (
@@ -74,7 +75,7 @@ unsigned int packet_filter(struct retis_packet_filter_ctx *ctx, u32 placeholder)
 		  "r4", "r5", "r6", "r7",
 		  "r8", "r9");
 
-	return ctx->ret;
-}
+ return ctx->ret;
+ } 
 
 #endif

retis/src/core/probe/kernel/bpf/raw_tracepoint.bpf.c

@@ -6,7 +6,7 @@
 /* It is safe to have these values per-object as the loaded object won't be
  * shared between attached programs for raw tracepoints.
  */
-const volatile u64 ksym = 0;
+ const volatile u64 ksym = 0;
 const volatile u32 nargs = 0;
 
 /* We unroll the loop bellow as the verifier disallow arithmetic operations on