Hi Yonghong, I tried to run the XDP samples from the bpf-next tip
today, and was hit by a regression.
Commit f7010770fbac ("tools/bpf: move bpf/lib netlink related
functions into a new file") adds a while(1) around the recv call in
bpf_set_link_xdp_fd making that call getting stuck in an infinite
loop.
I simply removed the loop, and that solved my problem (patch below).
However, I don't know if removing the loop would break bpftool for
you. If not, I can submit the patch as a proper one for bpf-next.
Thanks!
Björn
From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= <bjorn.to...@intel.com>
Date: Tue, 11 Sep 2018 12:35:44 +0200
Subject: [PATCH] tools/bpf: remove loop around netlink recv
Commit f7010770fbac ("tools/bpf: move bpf/lib netlink related
functions into a new file") moved the bpf_set_link_xdp_fd and split it
up into multiple functions. The added receive function
bpf_netlink_recv added a loop around the recv syscall leading to
multiple recv calls. This resulted in all XDP samples in the
samples/bpf/ to stop working, since they were stuck in a blocking
recv.
This commits removes the while (1)-statement.
Fixes: f7010770fbac ("tools/bpf: move bpf/lib netlink related
functions into a new file")
Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
---
tools/lib/bpf/netlink.c | 64 ++++++++++++++++++++---------------------
1 file changed, 31 insertions(+), 33 deletions(-)
diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index 469e068dd0c5..0eae1fbf46c6 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -70,41 +70,39 @@ static int bpf_netlink_recv(int sock, __u32 nl_pid, int seq,
char buf[4096];
int len, ret;
- while (1) {
- len = recv(sock, buf, sizeof(buf), 0);
- if (len < 0) {
- ret = -errno;
+ len = recv(sock, buf, sizeof(buf), 0);
+ if (len < 0) {
+ ret = -errno;
+ goto done;
+ }
+
+ for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
+ nh = NLMSG_NEXT(nh, len)) {
+ if (nh->nlmsg_pid != nl_pid) {
+ ret = -LIBBPF_ERRNO__WRNGPID;
goto done;
}
-
- for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
- nh = NLMSG_NEXT(nh, len)) {
- if (nh->nlmsg_pid != nl_pid) {
- ret = -LIBBPF_ERRNO__WRNGPID;
- goto done;
- }
- if (nh->nlmsg_seq != seq) {
- ret = -LIBBPF_ERRNO__INVSEQ;
- goto done;
- }
- switch (nh->nlmsg_type) {
- case NLMSG_ERROR:
- err = (struct nlmsgerr *)NLMSG_DATA(nh);
- if (!err->error)
- continue;
- ret = err->error;
- nla_dump_errormsg(nh);
- goto done;
- case NLMSG_DONE:
- return 0;
- default:
- break;
- }
- if (_fn) {
- ret = _fn(nh, fn, cookie);
- if (ret)
- return ret;
- }
+ if (nh->nlmsg_seq != seq) {
+ ret = -LIBBPF_ERRNO__INVSEQ;
+ goto done;
+ }
+ switch (nh->nlmsg_type) {
+ case NLMSG_ERROR:
+ err = (struct nlmsgerr *)NLMSG_DATA(nh);
+ if (!err->error)
+ continue;
+ ret = err->error;
+ nla_dump_errormsg(nh);
+ goto done;
+ case NLMSG_DONE:
+ return 0;
+ default:
+ break;
+ }
+ if (_fn) {
+ ret = _fn(nh, fn, cookie);
+ if (ret)
+ return ret;
}
}
ret = 0;
--
2.17.1
