[PULL 07/20] virtio-net: Do not propagate ebpf-rss-fds errors

[Jason Wang]

From: Akihiko Odaki <akihiko.odaki@daynix.com>

Propagating ebpf-rss-fds errors has several problems.

First, it makes device realization fail and disables the fallback to the
conventional eBPF loading.

Second, it leaks memory by making device realization fail without
freeing memory already allocated.

Third, the convention is to set an error when a function returns false,
but virtio_net_load_ebpf_fds() and virtio_net_load_ebpf() returns false
without setting an error, which is confusing.

Remove the propagation to fix these problems.

Fixes: 0524ea0510a3 ("ebpf: Added eBPF initialization by fds.")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index ff600b3002..3cee2ef3ac 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1329,24 +1329,22 @@ static void virtio_net_detach_epbf_rss(VirtIONet *n)
     virtio_net_attach_ebpf_to_backend(n->nic, -1);
 }
 
-static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp)
+static bool virtio_net_load_ebpf_fds(VirtIONet *n)
 {
     int fds[EBPF_RSS_MAX_FDS] = { [0 ... EBPF_RSS_MAX_FDS - 1] = -1};
     int ret = true;
     int i = 0;
 
-    ERRP_GUARD();
-
     if (n->nr_ebpf_rss_fds != EBPF_RSS_MAX_FDS) {
-        error_setg(errp,
-                  "Expected %d file descriptors but got %d",
-                  EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds);
+        warn_report("Expected %d file descriptors but got %d",
+                    EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds);
        return false;
    }
 
     for (i = 0; i < n->nr_ebpf_rss_fds; i++) {
-        fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], errp);
-        if (*errp) {
+        fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i],
+                                  &error_warn);
+        if (fds[i] < 0) {
             ret = false;
             goto exit;
         }
@@ -1355,7 +1353,7 @@ static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error 
**errp)
     ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]);
 
 exit:
-    if (!ret || *errp) {
+    if (!ret) {
         for (i = 0; i < n->nr_ebpf_rss_fds && fds[i] != -1; i++) {
             close(fds[i]);
         }
@@ -1364,13 +1362,12 @@ exit:
     return ret;
 }
 
-static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp)
+static bool virtio_net_load_ebpf(VirtIONet *n)
 {
     bool ret = false;
 
     if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
-        if (!(n->ebpf_rss_fds
-                && virtio_net_load_ebpf_fds(n, errp))) {
+        if (!(n->ebpf_rss_fds && virtio_net_load_ebpf_fds(n))) {
             ret = ebpf_rss_load(&n->ebpf_rss);
         }
     }
@@ -3809,7 +3806,7 @@ static void virtio_net_device_realize(DeviceState *dev, 
Error **errp)
     net_rx_pkt_init(&n->rx_pkt);
 
     if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) {
-        virtio_net_load_ebpf(n, errp);
+        virtio_net_load_ebpf(n);
     }
 }
 
-- 
2.42.0