Use of select() after the first call to mnl_socket_recvfrom() was
incorrect, FD_SET() was called after the call to select() returned. This
effectively turned the FD_ISSET() check into a noop (always true
condition).
Rewrite the receive loop using mnl_nft_event_listener() as an example:
* Combine the two calls to FD_ZERO(), FD_SET() and select() into one at
loop start.
* Check ENOBUFS condition and warn the user, also upon other errors.
* Continue on ENOBUFS, it is not a permanent error.
Signed-off-by: Phil Sutter <phil@xxxxxx>
---
src/mnl.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/src/mnl.c b/src/mnl.c
index 06280aa2cb50a..4fbfd059c0228 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -299,34 +299,39 @@ int mnl_batch_talk(struct netlink_ctx *ctx, struct list_head *err_list)
if (ret == -1)
return -1;
- FD_ZERO(&readfds);
- FD_SET(fd, &readfds);
+ while (true) {
+ FD_ZERO(&readfds);
+ FD_SET(fd, &readfds);
- /* receive and digest all the acknowledgments from the kernel. */
- ret = select(fd+1, &readfds, NULL, NULL, &tv);
- if (ret == -1)
- return -1;
+ /* receive and digest all the acknowledgments from the kernel. */
+ ret = select(fd + 1, &readfds, NULL, NULL, &tv);
+ if (ret < 0)
+ return -1;
- while (ret > 0 && FD_ISSET(fd, &readfds)) {
- struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buf;
+ if (!FD_ISSET(fd, &readfds))
+ break;
ret = mnl_socket_recvfrom(nl, rcv_buf, sizeof(rcv_buf));
- if (ret == -1)
- return -1;
+ if (ret < 0) {
+ if (errno == ENOBUFS) {
+ nft_print(&ctx->nft->output,
+ "# ERROR: We lost some netlink events!\n");
+ continue;
+ }
+ nft_print(&ctx->nft->output, "# ERROR: %s\n",
+ strerror(errno));
+ err = ret;
+ break;
+ }
ret = mnl_cb_run(rcv_buf, ret, 0, portid, &netlink_echo_callback, ctx);
/* Continue on error, make sure we get all acknowledgments */
if (ret == -1) {
+ struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buf;
+
mnl_err_list_node_add(err_list, errno, nlh->nlmsg_seq);
err = -1;
}
-
- ret = select(fd+1, &readfds, NULL, NULL, &tv);
- if (ret == -1)
- return -1;
-
- FD_ZERO(&readfds);
- FD_SET(fd, &readfds);
}
return err;
}
--
2.21.0
