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Thu, 12 Mar 2026 05:24:43 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Thu, 12 Mar 2026 13:24:42 +0100 To: Sun Jian Cc: bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, andrii@kernel.org, shuah@kernel.org, ast@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, martin.lau@linux.dev Subject: Re: [PATCH] selftests/bpf: modify_return: isolate fmod_ret hooks by pid Message-ID: References: <20260312104219.1208802-1-sun.jian.kdev@gmail.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260312104219.1208802-1-sun.jian.kdev@gmail.com> On Thu, Mar 12, 2026 at 06:42:19PM +0800, Sun Jian wrote: SNIP > diff --git a/tools/testing/selftests/bpf/progs/modify_return.c b/tools/testing/selftests/bpf/progs/modify_return.c > index 3376d4849f58..5ff18ddb3050 100644 > --- a/tools/testing/selftests/bpf/progs/modify_return.c > +++ b/tools/testing/selftests/bpf/progs/modify_return.c > @@ -7,16 +7,29 @@ > #include > #include > #include > +#include > > char _license[] SEC("license") = "GPL"; > > static int sequence = 0; > __s32 input_retval = 0; > +__u32 test_pid = 0; > + > +static __always_inline bool match_pid(void) > +{ > + __u64 pid_tgid = bpf_get_current_pid_tgid(); > + > + if (!test_pid) > + return false; > + return (__u32)(pid_tgid >> 32) == test_pid; > +} > > __u64 fentry_result = 0; > SEC("fentry/bpf_modify_return_test") > int BPF_PROG(fentry_test, int a, __u64 b) > { > + if (!match_pid()) > + return 0; I think just simple pid check like we do in other places should be enough: if (bpf_get_current_pid_tgid() >> 32 != test_pid) return 0; jirka > sequence++; > fentry_result = (sequence == 1); > return 0; > @@ -26,6 +39,8 @@ __u64 fmod_ret_result = 0; > SEC("fmod_ret/bpf_modify_return_test") > int BPF_PROG(fmod_ret_test, int a, int *b, int ret) > { > + if (!match_pid()) > + return ret; > sequence++; > /* This is the first fmod_ret program, the ret passed should be 0 */ > fmod_ret_result = (sequence == 2 && ret == 0); > @@ -36,6 +51,8 @@ __u64 fexit_result = 0; > SEC("fexit/bpf_modify_return_test") > int BPF_PROG(fexit_test, int a, __u64 b, int ret) > { > + if (!match_pid()) > + return 0; > sequence++; > /* If the input_reval is non-zero a successful modification should have > * occurred. > @@ -55,6 +72,8 @@ SEC("fentry/bpf_modify_return_test2") > int BPF_PROG(fentry_test2, int a, int *b, short c, int d, void *e, char f, > int g) > { > + if (!match_pid()) > + return 0; > sequence2++; > fentry_result2 = (sequence2 == 1); > return 0; > @@ -65,6 +84,8 @@ SEC("fmod_ret/bpf_modify_return_test2") > int BPF_PROG(fmod_ret_test2, int a, int *b, short c, int d, void *e, char f, > int g, int ret) > { > + if (!match_pid()) > + return ret; > sequence2++; > /* This is the first fmod_ret program, the ret passed should be 0 */ > fmod_ret_result2 = (sequence2 == 2 && ret == 0); > @@ -76,6 +97,8 @@ SEC("fexit/bpf_modify_return_test2") > int BPF_PROG(fexit_test2, int a, int *b, short c, int d, void *e, char f, > int g, int ret) > { > + if (!match_pid()) > + return 0; > sequence2++; > /* If the input_reval is non-zero a successful modification should have > * occurred. > > base-commit: 80234b5ab240f52fa45d201e899e207b9265ef91 > -- > 2.43.0 > >