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From: Juhee Kang <>
To: Daniel Borkmann <>,
	Alexei Starovoitov <>,
	Andrii Nakryiko <>
Subject: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument
Date: Sat, 24 Jul 2021 15:21:23 +0000	[thread overview]
Message-ID: <> (raw)

The current behavior of 'tracex7' doesn't consist with other bpf samples
tracex{1..6}. Other samples do not require any argument to run with, but
tracex7 should be run with btrfs device argument. (it should be executed

Currently, tracex7 doesn't have any description about how to run this
program and raises an unexpected error. And this result might be
confusing since users might not have a hunch about how to run this

    // Current behavior
    # ./tracex7
    sh: 1: Syntax error: word unexpected (expecting ")")
    // Fixed behavior
    # ./tracex7
    ERROR: Run with the btrfs device argument!

In order to fix this error, this commit adds logic to report a message
and exit when running this program with a missing argument.

Additionally in, there is a problem with
multiple directory(tmpmnt) creation. So in this commit adds a line with
removing the directory with every execution.

Signed-off-by: Juhee Kang <>
 samples/bpf/ | 1 +
 samples/bpf/tracex7_user.c          | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/samples/bpf/ b/samples/bpf/
index e68b9ee6814b..6480b55502c7 100755
--- a/samples/bpf/
+++ b/samples/bpf/
@@ -1,5 +1,6 @@
+rm -rf tmpmnt
 rm -f testfile.img
 dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1
 DEVICE=$(losetup --show -f testfile.img)
diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c
index fdcd6580dd73..8be7ce18d3ba 100644
--- a/samples/bpf/tracex7_user.c
+++ b/samples/bpf/tracex7_user.c
@@ -14,6 +14,11 @@ int main(int argc, char **argv)
 	int ret = 0;
 	FILE *f;
+	if (!argv[1]) {
+		fprintf(stderr, "ERROR: Run with the btrfs device argument!\n");
+		return 0;
+	}
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 	obj = bpf_object__open_file(filename, NULL);
 	if (libbpf_get_error(obj)) {

             reply	other threads:[~2021-07-24 15:21 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-24 15:21 Juhee Kang [this message]
2021-07-24 15:21 ` [bpf-next 2/2] samples: bpf: Add the omitted xdp samples to .gitignore Juhee Kang
2021-07-26  2:34   ` Yonghong Song
2021-07-26  2:34 ` [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument Yonghong Song
2021-07-26 20:08 ` Andrii Nakryiko
2021-07-27  3:32   ` Juhee Kang

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