WARNING: Macros with flow control statements should be avoided
#132: FILE: kernel/bpf/syscall.c:2878:
+#define DEFINE_BPF_MULTI_FUNC(args...)			\
+	extern int bpf_multi_func(args);		\
+	int __init bpf_multi_func(args) { return 0; }

WARNING: externs should be avoided in .c files
#133: FILE: kernel/bpf/syscall.c:2879:
+	extern int bpf_multi_func(args);		\

WARNING: line length of 95 exceeds 80 columns
#185: FILE: kernel/bpf/syscall.c:3029:
+	prog->aux->attach_btf_id = multi_func ? bpf_multi_func_btf_id[0] : attr->attach_btf_id;

WARNING: line length of 82 exceeds 80 columns
#207: FILE: kernel/bpf/trampoline.c:185:
+		    eatype == BPF_MODIFY_RETURN || eatype == BPF_TRACE_FSESSION ||

WARNING: line length of 88 exceeds 80 columns
#208: FILE: kernel/bpf/trampoline.c:186:
+		    eatype == BPF_TRACE_FENTRY_MULTI || eatype == BPF_TRACE_FEXIT_MULTI)

WARNING: line length of 98 exceeds 80 columns
#252: FILE: kernel/bpf/verifier.c:24959:
+	return is_tracing_multi(prog->expected_attach_type) && bpf_multi_func_btf_id[0] == btf_id;

WARNING: line length of 96 exceeds 80 columns
#290: FILE: kernel/bpf/verifier.c:25254:
+				/* *.multi sleepable programs will pass initial sleepable check,

WARNING: line length of 96 exceeds 80 columns
#291: FILE: kernel/bpf/verifier.c:25255:
+				 * the actual attached btf ids are checked later during the link

WARNING: line length of 85 exceeds 80 columns
#300: FILE: kernel/bpf/verifier.c:25263:
+				else if (!check_non_sleepable_error_inject(btf_id) &&

CHECK: Alignment should match open parenthesis
#301: FILE: kernel/bpf/verifier.c:25264:
+				else if (!check_non_sleepable_error_inject(btf_id) &&
 				    within_error_injection_list(addr))

total: 0 errors, 9 warnings, 1 checks, 256 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

Commit 31d79aa1d234 ("bpf: Add multi tracing attach types") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT BAD_REPORTED_BY_LINK CAMELCASE COMMIT_LOG_LONG_LINE FILE_PATH_CHANGES GIT_COMMIT_ID MACRO_ARG_REUSE NO_AUTHOR_SIGN_OFF

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.
total: 0 errors, 9 warnings, 1 checks, 256 lines checked