netdev - [PATCH v5 11/15] tools/bpf/bpftool: use TASK_COMM_LEN

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Date:   Thu, 21 Oct 2021 03:45:59 +0000
From:   Yafang Shao <laoar.shao@...il.com>
To:     keescook@...omium.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, arnaldo.melo@...il.com,
        pmladek@...e.com, peterz@...radead.org, viro@...iv.linux.org.uk,
        akpm@...ux-foundation.org, valentin.schneider@....com,
        qiang.zhang@...driver.com, robdclark@...omium.org,
        christian@...uner.io, dietmar.eggemann@....com, mingo@...hat.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        davem@...emloft.net, kuba@...nel.org, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, john.fastabend@...il.com,
        kpsingh@...nel.org
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-perf-users@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, oliver.sang@...el.com, lkp@...el.com,
        Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH v5 11/15] tools/bpf/bpftool: use TASK_COMM_LEN_16 instead of hard-coded 16

Use TASK_COMM_LEN_16 instead of hard-coded 16 to make it more grepable.
It uses bpf_probe_read_kernel() to get task comm, which may return a
string without nul terminator. We should use bpf_probe_read_kernel_str()
instead.

Signed-off-by: Yafang Shao <laoar.shao@...il.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Petr Mladek <pmladek@...e.com>
---
 tools/bpf/bpftool/Makefile                | 1 +
 tools/bpf/bpftool/main.h                  | 3 ++-
 tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 4 ++--
 tools/bpf/bpftool/skeleton/pid_iter.h     | 4 +++-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index d73232be1e99..33fbde84993c 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -164,6 +164,7 @@ $(OUTPUT)%.bpf.o: skeleton/%.bpf.c $(OUTPUT)vmlinux.h $(LIBBPF)
 	$(QUIET_CLANG)$(CLANG) \
 		-I$(if $(OUTPUT),$(OUTPUT),.) \
 		-I$(srctree)/tools/include/uapi/ \
+		-I$(srctree)/tools/include/ \
 		-I$(LIBBPF_PATH) \
 		-I$(srctree)/tools/lib \
 		-g -O2 -Wall -target bpf -c $< -o $@ && $(LLVM_STRIP) -g $@
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 90caa42aac4c..5efa27188f68 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -12,6 +12,7 @@
 #include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/hashtable.h>
+#include <linux/sched/task.h>
 #include <tools/libc_compat.h>
 
 #include <bpf/libbpf.h>
@@ -124,7 +125,7 @@ struct obj_refs_table {
 
 struct obj_ref {
 	int pid;
-	char comm[16];
+	char comm[TASK_COMM_LEN_16];
 };
 
 struct obj_refs {
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
index d9b420972934..f70702fcb224 100644
--- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
+++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
@@ -71,8 +71,8 @@ int iter(struct bpf_iter__task_file *ctx)
 
 	e.pid = task->tgid;
 	e.id = get_obj_id(file->private_data, obj_type);
-	bpf_probe_read_kernel(&e.comm, sizeof(e.comm),
-			      task->group_leader->comm);
+	bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm),
+				  task->group_leader->comm);
 	bpf_seq_write(ctx->meta->seq, &e, sizeof(e));
 
 	return 0;
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.h b/tools/bpf/bpftool/skeleton/pid_iter.h
index 5692cf257adb..675b2916567e 100644
--- a/tools/bpf/bpftool/skeleton/pid_iter.h
+++ b/tools/bpf/bpftool/skeleton/pid_iter.h
@@ -3,10 +3,12 @@
 #ifndef __PID_ITER_H
 #define __PID_ITER_H
 
+#include <linux/sched/task.h>
+
 struct pid_iter_entry {
 	__u32 id;
 	int pid;
-	char comm[16];
+	char comm[TASK_COMM_LEN_16];
 };
 
 #endif
-- 
2.17.1