[PATCH -mm 0/5] Phase 2 of task comm cleanups

[PATCH -mm 0/5] Phase 2 of task comm cleanups

[Yafang Shao]

This is the followup work of task comm cleanups[1].

In this phase, the hard-coded 16 is replaced by either TASK_COMM_LEN or
TASK_COMM_LEN_16, to make it grepable. The difference between this two 
marcos is: 
- TASK_COMM_LEN
  The size should be same with the TASK_COMM_LEN defined in linux/sched.h.
  For the src file which can't include linux/sched.h, a macro with the 
  the same name is defined in this file specifically. 
- TASK_COMM_LEN_16
  The size must be a fixed-size 16. It may be exposed to userspace so we
  can't change it. 

In order to include vmlinux.h in bpf progs under sample/bpf or
tools/testing/selftests/bpf, some structs are renamed and some included
headers are removed.

1. https://lore.kernel.org/lkml/20211120112738.45980-1-laoar.shao@gmail.com/

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>

Yafang Shao (5):
  elfcore: replace old hard-code 16 with TASK_COMM_LEN_16
  cn_proc: replaced old hard-coded 16 with TASK_COMM_LEN_16
  samples/bpf/tracex2: replace hard-coded 16 with TASK_COMM_LEN
  tools/perf: replace hard-coded 16 with TASK_COMM_LEN
  bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

 include/linux/elfcore-compat.h                        |  8 ++------
 include/linux/elfcore.h                               |  9 ++-------
 include/linux/sched.h                                 |  5 +++++
 include/uapi/linux/cn_proc.h                          |  4 +++-
 samples/bpf/tracex2_kern.c                            |  3 ++-
 samples/bpf/tracex2_user.c                            |  3 ++-
 tools/perf/tests/evsel-tp-sched.c                     |  8 +++++---
 tools/testing/selftests/bpf/prog_tests/ringbuf.c      |  9 +++++----
 .../testing/selftests/bpf/prog_tests/ringbuf_multi.c  |  8 +++++---
 .../selftests/bpf/prog_tests/sk_storage_tracing.c     |  3 ++-
 .../testing/selftests/bpf/prog_tests/test_overhead.c  |  3 ++-
 .../selftests/bpf/prog_tests/trampoline_count.c       |  3 ++-
 .../selftests/bpf/progs/test_core_reloc_kernel.c      | 11 +++++------
 tools/testing/selftests/bpf/progs/test_ringbuf.c      |  8 ++++----
 .../testing/selftests/bpf/progs/test_ringbuf_multi.c  |  8 ++++----
 .../selftests/bpf/progs/test_sk_storage_tracing.c     |  4 ++--
 16 files changed, 52 insertions(+), 45 deletions(-)

-- 
2.17.1

[PATCH -mm 1/5] elfcore: replace old hard-code 16 with TASK_COMM_LEN_16

[Yafang Shao]

A new macro TASK_COMM_LEN_16 is introduced for the old hard-coded 16 to
make it more grepable. As explained above this marco, the difference
between TASK_COMM_LEN and TASK_COMM_LEN_16 is that TASK_COMM_LEN_16 must
be a fixed size 16 and can't be changed.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 include/linux/elfcore-compat.h | 8 ++------
 include/linux/elfcore.h        | 9 ++-------
 include/linux/sched.h          | 5 +++++
 3 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h
index 54feb64e9b5d..69fa1a728964 100644
--- a/include/linux/elfcore-compat.h
+++ b/include/linux/elfcore-compat.h
@@ -5,6 +5,7 @@
 #include <linux/elf.h>
 #include <linux/elfcore.h>
 #include <linux/compat.h>
+#include <linux/sched.h>
 
 /*
  * Make sure these layouts match the linux/elfcore.h native definitions.
@@ -43,12 +44,7 @@ struct compat_elf_prpsinfo
 	__compat_uid_t			pr_uid;
 	__compat_gid_t			pr_gid;
 	compat_pid_t			pr_pid, pr_ppid, pr_pgrp, pr_sid;
-	/*
-	 * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
-	 * changed as it is exposed to userspace. We'd better make it hard-coded
-	 * here.
-	 */
-	char				pr_fname[16];
+	char				pr_fname[TASK_COMM_LEN_16];
 	char				pr_psargs[ELF_PRARGSZ];
 };
 
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 746e081879a5..d3bb4bd3c985 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -65,13 +65,8 @@ struct elf_prpsinfo
 	__kernel_gid_t	pr_gid;
 	pid_t	pr_pid, pr_ppid, pr_pgrp, pr_sid;
 	/* Lots missing */
-	/*
-	 * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
-	 * changed as it is exposed to userspace. We'd better make it hard-coded
-	 * here.
-	 */
-	char	pr_fname[16];	/* filename of executable */
-	char	pr_psargs[ELF_PRARGSZ];	/* initial part of arg list */
+	char	pr_fname[TASK_COMM_LEN_16];	/* filename of executable */
+	char	pr_psargs[ELF_PRARGSZ];		/* initial part of arg list */
 };
 
 static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c79bd7ee6029..8d963a50a2a8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -279,6 +279,11 @@ struct task_group;
  * BPF programs.
  */
 enum {
+	/*
+	 * For the old hard-coded 16, which is exposed to userspace and can't
+	 * be changed.
+	 */
+	TASK_COMM_LEN_16 = 16,
 	TASK_COMM_LEN = 16,
 };
 
-- 
2.17.1

[PATCH -mm 2/5] cn_proc: replaced old hard-coded 16 with TASK_COMM_LEN_16

[Yafang Shao]

This TASK_COMM_LEN_16 has the same meaning with the macro defined in
linux/sched.h, but we can't include linux/sched.h in a UAPI header, so
we should specifically define it in the cn_proc.h.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 include/uapi/linux/cn_proc.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/cn_proc.h b/include/uapi/linux/cn_proc.h
index db210625cee8..6dcccaed383f 100644
--- a/include/uapi/linux/cn_proc.h
+++ b/include/uapi/linux/cn_proc.h
@@ -21,6 +21,8 @@
 
 #include <linux/types.h>
 
+#define TASK_COMM_LEN_16 16
+
 /*
  * Userspace sends this enum to register with the kernel that it is listening
  * for events on the connector.
@@ -110,7 +112,7 @@ struct proc_event {
 		struct comm_proc_event {
 			__kernel_pid_t process_pid;
 			__kernel_pid_t process_tgid;
-			char           comm[16];
+			char           comm[TASK_COMM_LEN_16];
 		} comm;
 
 		struct coredump_proc_event {
-- 
2.17.1

[PATCH -mm 3/5] samples/bpf/tracex2: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

The comm used in tracex2 should have the same size with the comm in
task_struct, we'd better define the size of it as TASK_COMM_LEN to make it
more grepable.

linux/sched.h can be included in tracex2 kernel code, but it can't be
included in tracex2 userspace code. So a new marco TASK_COMM_LEN is
defined in tracex2 userspace code.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 samples/bpf/tracex2_kern.c | 3 ++-
 samples/bpf/tracex2_user.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/samples/bpf/tracex2_kern.c b/samples/bpf/tracex2_kern.c
index 5bc696bac27d..51dbaf765cd5 100644
--- a/samples/bpf/tracex2_kern.c
+++ b/samples/bpf/tracex2_kern.c
@@ -7,6 +7,7 @@
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/version.h>
+#include <linux/sched.h>
 #include <uapi/linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
@@ -65,7 +66,7 @@ static unsigned int log2l(unsigned long v)
 }
 
 struct hist_key {
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 	u64 pid_tgid;
 	u64 uid_gid;
 	u64 index;
diff --git a/samples/bpf/tracex2_user.c b/samples/bpf/tracex2_user.c
index 1626d51dfffd..b728a946d83d 100644
--- a/samples/bpf/tracex2_user.c
+++ b/samples/bpf/tracex2_user.c
@@ -12,6 +12,7 @@
 
 #define MAX_INDEX	64
 #define MAX_STARS	38
+#define TASK_COMM_LEN	16
 
 /* my_map, my_hist_map */
 static int map_fd[2];
@@ -28,7 +29,7 @@ static void stars(char *str, long val, long max, int width)
 }
 
 struct task {
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 	__u64 pid_tgid;
 	__u64 uid_gid;
 };
-- 
2.17.1

[PATCH -mm 4/5] tools/perf: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

evsel-tp-sched will verify the task comm len in sched:sched_switch
and sched:sched_wakeup tracepoints. The len must be same with TASK_COMM_LEN
defined in linux/sched.h. In order to make it grepable, we'd better replace
the hard-coded 16 with TASK_COMM_LEN.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 tools/perf/tests/evsel-tp-sched.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/perf/tests/evsel-tp-sched.c b/tools/perf/tests/evsel-tp-sched.c
index cf4da3d748c2..83e0ce2e676f 100644
--- a/tools/perf/tests/evsel-tp-sched.c
+++ b/tools/perf/tests/evsel-tp-sched.c
@@ -5,6 +5,8 @@
 #include "tests.h"
 #include "debug.h"
 
+#define TASK_COMM_LEN 16
+
 static int evsel__test_field(struct evsel *evsel, const char *name, int size, bool should_be_signed)
 {
 	struct tep_format_field *field = evsel__field(evsel, name);
@@ -43,7 +45,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
 		return -1;
 	}
 
-	if (evsel__test_field(evsel, "prev_comm", 16, false))
+	if (evsel__test_field(evsel, "prev_comm", TASK_COMM_LEN, false))
 		ret = -1;
 
 	if (evsel__test_field(evsel, "prev_pid", 4, true))
@@ -55,7 +57,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
 	if (evsel__test_field(evsel, "prev_state", sizeof(long), true))
 		ret = -1;
 
-	if (evsel__test_field(evsel, "next_comm", 16, false))
+	if (evsel__test_field(evsel, "next_comm", TASK_COMM_LEN, false))
 		ret = -1;
 
 	if (evsel__test_field(evsel, "next_pid", 4, true))
@@ -73,7 +75,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
 		return -1;
 	}
 
-	if (evsel__test_field(evsel, "comm", 16, false))
+	if (evsel__test_field(evsel, "comm", TASK_COMM_LEN, false))
 		ret = -1;
 
 	if (evsel__test_field(evsel, "pid", 4, true))
-- 
2.17.1

[PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

The comm used in these bpf progs should have the same size with the comm
field in struct task_struct defined in linux/sched.h. We'd better define
the size as TASK_COMM_LEN to make it more grepable.

The bpf progs kernel code can inlcude vmlinux.h generated by BTF CO-RE
to use TASK_COMM_LEN, while the userspace code can't include it so
TASK_COMM_LEN is specifically defined in the userspace code.

In order to fix redefinitions caused by the new included vmlinux.h, some
headers are removed and some structs are renamed.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 tools/testing/selftests/bpf/prog_tests/ringbuf.c      |  9 +++++----
 .../testing/selftests/bpf/prog_tests/ringbuf_multi.c  |  8 +++++---
 .../selftests/bpf/prog_tests/sk_storage_tracing.c     |  3 ++-
 .../testing/selftests/bpf/prog_tests/test_overhead.c  |  3 ++-
 .../selftests/bpf/prog_tests/trampoline_count.c       |  3 ++-
 .../selftests/bpf/progs/test_core_reloc_kernel.c      | 11 +++++------
 tools/testing/selftests/bpf/progs/test_ringbuf.c      |  8 ++++----
 .../testing/selftests/bpf/progs/test_ringbuf_multi.c  |  8 ++++----
 .../selftests/bpf/progs/test_sk_storage_tracing.c     |  4 ++--
 9 files changed, 31 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
index 9a80fe8a6427..39e43245db0a 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
@@ -15,14 +15,15 @@
 #include "test_ringbuf.lskel.h"
 
 #define EDONE 7777
+#define TASK_COMM_LEN 16
 
 static int duration = 0;
 
-struct sample {
+struct sample_ringbuf {
 	int pid;
 	int seq;
 	long value;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 static int sample_cnt;
@@ -39,7 +40,7 @@ static int atomic_xchg(int *cnt, int val)
 
 static int process_sample(void *ctx, void *data, size_t len)
 {
-	struct sample *s = data;
+	struct sample_ringbuf *s = data;
 
 	atomic_inc(&sample_cnt);
 
@@ -83,7 +84,7 @@ static void *poll_thread(void *input)
 
 void test_ringbuf(void)
 {
-	const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample);
+	const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample_ringbuf);
 	pthread_t thread;
 	long bg_ret = -1;
 	int err, cnt, rb_fd;
diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
index e945195b24c9..cb592555513f 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
@@ -4,19 +4,21 @@
 #include <sys/epoll.h>
 #include "test_ringbuf_multi.skel.h"
 
+#define TASK_COMM_LEN 16
+
 static int duration = 0;
 
-struct sample {
+struct sample_ringbuf {
 	int pid;
 	int seq;
 	long value;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 static int process_sample(void *ctx, void *data, size_t len)
 {
 	int ring = (unsigned long)ctx;
-	struct sample *s = data;
+	struct sample_ringbuf *s = data;
 
 	switch (s->seq) {
 	case 0:
diff --git a/tools/testing/selftests/bpf/prog_tests/sk_storage_tracing.c b/tools/testing/selftests/bpf/prog_tests/sk_storage_tracing.c
index 547ae53cde74..dbbdbf4400d7 100644
--- a/tools/testing/selftests/bpf/prog_tests/sk_storage_tracing.c
+++ b/tools/testing/selftests/bpf/prog_tests/sk_storage_tracing.c
@@ -11,11 +11,12 @@
 
 #define LO_ADDR6 "::1"
 #define TEST_COMM "test_progs"
+#define TASK_COMM_LEN 16
 
 struct sk_stg {
 	__u32 pid;
 	__u32 last_notclose_state;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 static struct test_sk_storage_tracing *skel;
diff --git a/tools/testing/selftests/bpf/prog_tests/test_overhead.c b/tools/testing/selftests/bpf/prog_tests/test_overhead.c
index 123c68c1917d..7fe60ec12fc4 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_overhead.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_overhead.c
@@ -6,6 +6,7 @@
 #include <test_progs.h>
 
 #define MAX_CNT 100000
+#define TASK_COMM_LEN 16
 
 static __u64 time_get_ns(void)
 {
@@ -67,7 +68,7 @@ void test_test_overhead(void)
 	struct bpf_object *obj;
 	struct bpf_link *link;
 	int err, duration = 0;
-	char comm[16] = {};
+	char comm[TASK_COMM_LEN] = {};
 
 	if (CHECK_FAIL(prctl(PR_GET_NAME, comm, 0L, 0L, 0L)))
 		return;
diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
index fc146671b20a..da83f7408aa8 100644
--- a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
+++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
@@ -5,6 +5,7 @@
 #include <test_progs.h>
 
 #define MAX_TRAMP_PROGS 38
+#define TASK_COMM_LEN 16
 
 struct inst {
 	struct bpf_object *obj;
@@ -51,7 +52,7 @@ void serial_test_trampoline_count(void)
 	int err, i = 0, duration = 0;
 	struct bpf_object *obj;
 	struct bpf_link *link;
-	char comm[16] = {};
+	char comm[TASK_COMM_LEN] = {};
 
 	/* attach 'allowed' trampoline programs */
 	for (i = 0; i < MAX_TRAMP_PROGS; i++) {
diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
index 145028b52ad8..7b1bb73c3501 100644
--- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
@@ -1,8 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2019 Facebook
 
-#include <linux/bpf.h>
-#include <stdint.h>
+#include <vmlinux.h>
 #include <stdbool.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_core_read.h>
@@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
 	int comm_len;
 };
 
-struct task_struct {
+struct task_struct_reloc {
 	int pid;
 	int tgid;
-	char comm[16];
-	struct task_struct *group_leader;
+	char comm[TASK_COMM_LEN];
+	struct task_struct_reloc *group_leader;
 };
 
 #define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)
@@ -35,7 +34,7 @@ struct task_struct {
 SEC("raw_tracepoint/sys_enter")
 int test_core_kernel(void *ctx)
 {
-	struct task_struct *task = (void *)bpf_get_current_task();
+	struct task_struct_reloc *task = (void *)bpf_get_current_task();
 	struct core_reloc_kernel_output *out = (void *)&data.out;
 	uint64_t pid_tgid = bpf_get_current_pid_tgid();
 	uint32_t real_tgid = (uint32_t)pid_tgid;
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf.c b/tools/testing/selftests/bpf/progs/test_ringbuf.c
index eaa7d9dba0be..45b28965f3a5 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf.c
@@ -1,16 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2020 Facebook
 
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
 char _license[] SEC("license") = "GPL";
 
-struct sample {
+struct sample_ringbuf {
 	int pid;
 	int seq;
 	long value;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 struct {
@@ -39,7 +39,7 @@ SEC("fentry/__x64_sys_getpgid")
 int test_ringbuf(void *ctx)
 {
 	int cur_pid = bpf_get_current_pid_tgid() >> 32;
-	struct sample *sample;
+	struct sample_ringbuf *sample;
 	int zero = 0;
 
 	if (cur_pid != pid)
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
index 197b86546dca..7c9db148f168 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
@@ -1,16 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2020 Facebook
 
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
 char _license[] SEC("license") = "GPL";
 
-struct sample {
+struct sample_ringbuf {
 	int pid;
 	int seq;
 	long value;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 struct ringbuf_map {
@@ -55,7 +55,7 @@ SEC("tp/syscalls/sys_enter_getpgid")
 int test_ringbuf(void *ctx)
 {
 	int cur_pid = bpf_get_current_pid_tgid() >> 32;
-	struct sample *sample;
+	struct sample_ringbuf *sample;
 	void *rb;
 	int zero = 0;
 
diff --git a/tools/testing/selftests/bpf/progs/test_sk_storage_tracing.c b/tools/testing/selftests/bpf/progs/test_sk_storage_tracing.c
index 6dc1f28fc4b6..cc41a09e3130 100644
--- a/tools/testing/selftests/bpf/progs/test_sk_storage_tracing.c
+++ b/tools/testing/selftests/bpf/progs/test_sk_storage_tracing.c
@@ -9,7 +9,7 @@
 struct sk_stg {
 	__u32 pid;
 	__u32 last_notclose_state;
-	char comm[16];
+	char comm[TASK_COMM_LEN];
 };
 
 struct {
@@ -27,7 +27,7 @@ struct {
 	__type(value, int);
 } del_sk_stg_map SEC(".maps");
 
-char task_comm[16] = "";
+char task_comm[TASK_COMM_LEN] = "";
 
 SEC("tp_btf/inet_sock_set_state")
 int BPF_PROG(trace_inet_sock_set_state, struct sock *sk, int oldstate,
-- 
2.17.1

Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Alexei Starovoitov]

On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>
>  static int process_sample(void *ctx, void *data, size_t len)
>  {
> -       struct sample *s = data;
> +       struct sample_ringbuf *s = data;

This is becoming pointless churn.
Nack.

> index 145028b52ad8..7b1bb73c3501 100644
> --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> @@ -1,8 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  // Copyright (c) 2019 Facebook
>
> -#include <linux/bpf.h>
> -#include <stdint.h>
> +#include <vmlinux.h>
>  #include <stdbool.h>
>  #include <bpf/bpf_helpers.h>
>  #include <bpf/bpf_core_read.h>
> @@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
>         int comm_len;
>  };
>
> -struct task_struct {
> +struct task_struct_reloc {

Churn that is not even compile tested.

Re: [PATCH -mm 3/5] samples/bpf/tracex2: replace hard-coded 16 with TASK_COMM_LEN

[Alexei Starovoitov]

On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> diff --git a/samples/bpf/tracex2_user.c b/samples/bpf/tracex2_user.c
> index 1626d51dfffd..b728a946d83d 100644
> --- a/samples/bpf/tracex2_user.c
> +++ b/samples/bpf/tracex2_user.c
> @@ -12,6 +12,7 @@
>
>  #define MAX_INDEX      64
>  #define MAX_STARS      38
> +#define TASK_COMM_LEN  16
>
>  /* my_map, my_hist_map */
>  static int map_fd[2];
> @@ -28,7 +29,7 @@ static void stars(char *str, long val, long max, int width)
>  }
>
>  struct task {
> -       char comm[16];
> +       char comm[TASK_COMM_LEN];

Also Nack.

Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

On Sun, Dec 5, 2021 at 12:44 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> >
> >  static int process_sample(void *ctx, void *data, size_t len)
> >  {
> > -       struct sample *s = data;
> > +       struct sample_ringbuf *s = data;
>
> This is becoming pointless churn.
> Nack.
>
> > index 145028b52ad8..7b1bb73c3501 100644
> > --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > @@ -1,8 +1,7 @@
> >  // SPDX-License-Identifier: GPL-2.0
> >  // Copyright (c) 2019 Facebook
> >
> > -#include <linux/bpf.h>
> > -#include <stdint.h>
> > +#include <vmlinux.h>
> >  #include <stdbool.h>
> >  #include <bpf/bpf_helpers.h>
> >  #include <bpf/bpf_core_read.h>
> > @@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
> >         int comm_len;
> >  };
> >
> > -struct task_struct {
> > +struct task_struct_reloc {
>
> Churn that is not even compile tested.

It is strange that I have successfully compiled it....
Below is the compile log,

$ cat make.log | grep test_core_reloc_kernel
  CLNG-BPF [test_maps] test_core_reloc_kernel.o
  GEN-SKEL [test_progs] test_core_reloc_kernel.skel.h
  CLNG-BPF [test_maps] test_core_reloc_kernel.o
  GEN-SKEL [test_progs-no_alu32] test_core_reloc_kernel.skel.h

Also there's no error in the compile log.

-- 
Thanks
Yafang

Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Alexei Starovoitov]

On Sat, Dec 4, 2021 at 6:45 PM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> On Sun, Dec 5, 2021 at 12:44 AM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
> >
> > On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> > >
> > >  static int process_sample(void *ctx, void *data, size_t len)
> > >  {
> > > -       struct sample *s = data;
> > > +       struct sample_ringbuf *s = data;
> >
> > This is becoming pointless churn.
> > Nack.
> >
> > > index 145028b52ad8..7b1bb73c3501 100644
> > > --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > @@ -1,8 +1,7 @@
> > >  // SPDX-License-Identifier: GPL-2.0
> > >  // Copyright (c) 2019 Facebook
> > >
> > > -#include <linux/bpf.h>
> > > -#include <stdint.h>
> > > +#include <vmlinux.h>
> > >  #include <stdbool.h>
> > >  #include <bpf/bpf_helpers.h>
> > >  #include <bpf/bpf_core_read.h>
> > > @@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
> > >         int comm_len;
> > >  };
> > >
> > > -struct task_struct {
> > > +struct task_struct_reloc {
> >
> > Churn that is not even compile tested.
>
> It is strange that I have successfully compiled it....
> Below is the compile log,
>
> $ cat make.log | grep test_core_reloc_kernel
>   CLNG-BPF [test_maps] test_core_reloc_kernel.o
>   GEN-SKEL [test_progs] test_core_reloc_kernel.skel.h
>   CLNG-BPF [test_maps] test_core_reloc_kernel.o
>   GEN-SKEL [test_progs-no_alu32] test_core_reloc_kernel.skel.h
>
> Also there's no error in the compile log.

and ran the tests too?

Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

On Sun, Dec 5, 2021 at 11:13 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sat, Dec 4, 2021 at 6:45 PM Yafang Shao <laoar.shao@gmail.com> wrote:
> >
> > On Sun, Dec 5, 2021 at 12:44 AM Alexei Starovoitov
> > <alexei.starovoitov@gmail.com> wrote:
> > >
> > > On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> > > >
> > > >  static int process_sample(void *ctx, void *data, size_t len)
> > > >  {
> > > > -       struct sample *s = data;
> > > > +       struct sample_ringbuf *s = data;
> > >
> > > This is becoming pointless churn.
> > > Nack.
> > >
> > > > index 145028b52ad8..7b1bb73c3501 100644
> > > > --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > > +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > > @@ -1,8 +1,7 @@
> > > >  // SPDX-License-Identifier: GPL-2.0
> > > >  // Copyright (c) 2019 Facebook
> > > >
> > > > -#include <linux/bpf.h>
> > > > -#include <stdint.h>
> > > > +#include <vmlinux.h>
> > > >  #include <stdbool.h>
> > > >  #include <bpf/bpf_helpers.h>
> > > >  #include <bpf/bpf_core_read.h>
> > > > @@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
> > > >         int comm_len;
> > > >  };
> > > >
> > > > -struct task_struct {
> > > > +struct task_struct_reloc {
> > >
> > > Churn that is not even compile tested.
> >
> > It is strange that I have successfully compiled it....
> > Below is the compile log,
> >
> > $ cat make.log | grep test_core_reloc_kernel
> >   CLNG-BPF [test_maps] test_core_reloc_kernel.o
> >   GEN-SKEL [test_progs] test_core_reloc_kernel.skel.h
> >   CLNG-BPF [test_maps] test_core_reloc_kernel.o
> >   GEN-SKEL [test_progs-no_alu32] test_core_reloc_kernel.skel.h
> >
> > Also there's no error in the compile log.
>
> and ran the tests too?

My bad. I thought it was just a name change, which will work well if
it can be compiled successfully.
But it seems the task_struct in this file is a dummy struct, which
will be relocated to the real task_struct defined in the kernel.
We can't include vmlinux.h in this file, as it is for the relocation test.

-- 
Thanks
Yafang

Re: [PATCH -mm 1/5] elfcore: replace old hard-code 16 with TASK_COMM_LEN_16

[Steven Rostedt]

On Sat,  4 Dec 2021 09:52:52 +0000
Yafang Shao <laoar.shao@gmail.com> wrote:

> A new macro TASK_COMM_LEN_16 is introduced for the old hard-coded 16 to
> make it more grepable. As explained above this marco, the difference
> between TASK_COMM_LEN and TASK_COMM_LEN_16 is that TASK_COMM_LEN_16 must
> be a fixed size 16 and can't be changed.

You could add:

Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

Re: [PATCH -mm 2/5] cn_proc: replaced old hard-coded 16 with TASK_COMM_LEN_16

[Steven Rostedt]

On Sat,  4 Dec 2021 09:52:53 +0000
Yafang Shao <laoar.shao@gmail.com> wrote:

> This TASK_COMM_LEN_16 has the same meaning with the macro defined in
> linux/sched.h, but we can't include linux/sched.h in a UAPI header, so
> we should specifically define it in the cn_proc.h.
> 

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Petr Mladek <pmladek@suse.com>
> ---
>  include/uapi/linux/cn_proc.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/cn_proc.h b/include/uapi/linux/cn_proc.h
> index db210625cee8..6dcccaed383f 100644
> --- a/include/uapi/linux/cn_proc.h
> +++ b/include/uapi/linux/cn_proc.h
> @@ -21,6 +21,8 @@
>  
>  #include <linux/types.h>
>  
> +#define TASK_COMM_LEN_16 16
> +
>  /*
>   * Userspace sends this enum to register with the kernel that it is listening
>   * for events on the connector.
> @@ -110,7 +112,7 @@ struct proc_event {
>  		struct comm_proc_event {
>  			__kernel_pid_t process_pid;
>  			__kernel_pid_t process_tgid;
> -			char           comm[16];
> +			char           comm[TASK_COMM_LEN_16];
>  		} comm;
>  
>  		struct coredump_proc_event {

Re: [PATCH -mm 4/5] tools/perf: replace hard-coded 16 with TASK_COMM_LEN

[Steven Rostedt]

On Sat,  4 Dec 2021 09:52:55 +0000
Yafang Shao <laoar.shao@gmail.com> wrote:

> @@ -43,7 +45,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
>  		return -1;
>  	}
>  
> -	if (evsel__test_field(evsel, "prev_comm", 16, false))
> +	if (evsel__test_field(evsel, "prev_comm", TASK_COMM_LEN, false))
>  		ret = -1;
>  
>  	if (evsel__test_field(evsel, "prev_pid", 4, true))
> @@ -55,7 +57,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
>  	if (evsel__test_field(evsel, "prev_state", sizeof(long), true))
>  		ret = -1;
>  
> -	if (evsel__test_field(evsel, "next_comm", 16, false))
> +	if (evsel__test_field(evsel, "next_comm", TASK_COMM_LEN, false))
>  		ret = -1;
>  
>  	if (evsel__test_field(evsel, "next_pid", 4, true))
> @@ -73,7 +75,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
>  		return -1;
>  	}
>  
> -	if (evsel__test_field(evsel, "comm", 16, false))
> +	if (evsel__test_field(evsel, "comm", TASK_COMM_LEN, false))

Shouldn't all these be TASK_COMM_LEN_16?

-- Steve

>  		ret = -1;
>  
>  	if (evsel__test_field(evsel, "pid", 4, true))

Re: [PATCH -mm 4/5] tools/perf: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao]

On Thu, Dec 9, 2021 at 2:43 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Sat,  4 Dec 2021 09:52:55 +0000
> Yafang Shao <laoar.shao@gmail.com> wrote:
>
> > @@ -43,7 +45,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
> >               return -1;
> >       }
> >
> > -     if (evsel__test_field(evsel, "prev_comm", 16, false))
> > +     if (evsel__test_field(evsel, "prev_comm", TASK_COMM_LEN, false))
> >               ret = -1;
> >
> >       if (evsel__test_field(evsel, "prev_pid", 4, true))
> > @@ -55,7 +57,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
> >       if (evsel__test_field(evsel, "prev_state", sizeof(long), true))
> >               ret = -1;
> >
> > -     if (evsel__test_field(evsel, "next_comm", 16, false))
> > +     if (evsel__test_field(evsel, "next_comm", TASK_COMM_LEN, false))
> >               ret = -1;
> >
> >       if (evsel__test_field(evsel, "next_pid", 4, true))
> > @@ -73,7 +75,7 @@ static int test__perf_evsel__tp_sched_test(struct test_suite *test __maybe_unuse
> >               return -1;
> >       }
> >
> > -     if (evsel__test_field(evsel, "comm", 16, false))
> > +     if (evsel__test_field(evsel, "comm", TASK_COMM_LEN, false))
>
> Shouldn't all these be TASK_COMM_LEN_16?
>

The value here must be the same with TASK_COMM_LEN, so I use TASK_COMM_LEN here.
But we may also change the code as
https://lore.kernel.org/lkml/20211101060419.4682-9-laoar.shao@gmail.com/
if TASK_COMM_LEN is changed, so TASK_COMM_LEN_16 is also okay here.
I will change it to TASK_COMM_LEN_16 in the next version.

>
> >               ret = -1;
> >
> >       if (evsel__test_field(evsel, "pid", 4, true))
>


-- 
Thanks
Yafang