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From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>
Subject: [PATCH bpf v2 3/3] bpftool: handle EAGAIN error code properly in pids collection
Date: Tue, 18 Aug 2020 15:23:12 -0700	[thread overview]
Message-ID: <20200818222312.2181675-1-yhs@fb.com> (raw)
In-Reply-To: <20200818222309.2181236-1-yhs@fb.com>

When the error code is EAGAIN, the kernel signals the user
space should retry the read() operation for bpf iterators.
Let us do it.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/bpf/bpftool/pids.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
index e3b116325403..df7d8ec76036 100644
--- a/tools/bpf/bpftool/pids.c
+++ b/tools/bpf/bpftool/pids.c
@@ -134,6 +134,8 @@ int build_obj_refs_table(struct obj_refs_table *table, enum bpf_obj_type type)
 	while (true) {
 		ret = read(fd, buf, sizeof(buf));
 		if (ret < 0) {
+			if (errno == EAGAIN)
+				continue;
 			err = -errno;
 			p_err("failed to read PID iterator output: %d", err);
 			goto out;
-- 
2.24.1


  parent reply	other threads:[~2020-08-18 22:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-18 22:23 [PATCH bpf v2 0/3] bpf: two fixes for bpf iterators Yonghong Song
2020-08-18 22:23 ` [PATCH bpf v2 1/3] bpf: fix a rcu_sched stall issue with bpf task/task_file iterator Yonghong Song
2020-08-19  0:05   ` Alexei Starovoitov
2020-08-19  0:30     ` Yonghong Song
2020-08-19  0:49       ` Alexei Starovoitov
2020-08-18 22:23 ` [PATCH bpf v2 2/3] bpf: avoid visit same object multiple times Yonghong Song
2020-08-18 22:23 ` Yonghong Song [this message]
2020-08-18 22:30   ` [PATCH bpf v2 3/3] bpftool: handle EAGAIN error code properly in pids collection Andrii Nakryiko
2020-08-18 22:28 ` [PATCH bpf v2 0/3] bpf: two fixes for bpf iterators Yonghong Song

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