net/tap: rework tap_set_sndbuf()

Keep NetdevTapOptions related logic in tap.c, and make tap_set_sndbuf a
simple system call wrapper, more like other functions in tap-linux.c

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Maksim Davydov <davydov-max@yandex-team.ru>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/tap-bsd.c

@@ -206,7 +206,7 @@ error:
 }
 #endif /* __FreeBSD__ */
 
-bool tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
+bool tap_set_sndbuf(int fd, int sndbuf, Error **errp)
 {
     return true;
 }

net/tap-linux.c

@@ -143,21 +143,9 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
  * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
  * a good value, given a 1500 byte MTU.
  */
-#define TAP_DEFAULT_SNDBUF 0
-
-bool tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
+bool tap_set_sndbuf(int fd, int sndbuf, Error **errp)
 {
-    int sndbuf;
-
-    sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :
-             tap->sndbuf > INT_MAX  ? INT_MAX :
-             tap->sndbuf;
-
-    if (!sndbuf) {
-        sndbuf = INT_MAX;
-    }
-
-    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
+    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1) {
         error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
         return false;
     }

net/tap-solaris.c

@@ -208,7 +208,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     return fd;
 }
 
-bool tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
+bool tap_set_sndbuf(int fd, int sndbuf, Error **errp)
 {
     return true;
 }

net/tap-stub.c

@@ -33,7 +33,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     return -1;
 }
 
-bool tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
+bool tap_set_sndbuf(int fd, int sndbuf, Error **errp)
 {
     return true;
 }

net/tap.c

@@ -711,8 +711,12 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 {
     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
     int vhostfd;
+    bool sndbuf_required = tap->has_sndbuf;
+    int sndbuf =
+        (tap->has_sndbuf && tap->sndbuf) ? MIN(tap->sndbuf, INT_MAX) : INT_MAX;
 
-    if (!tap_set_sndbuf(s->fd, tap, errp)) {
+    if (!tap_set_sndbuf(fd, sndbuf, sndbuf_required ? errp : NULL) &&
+        sndbuf_required) {
         goto failed;
     }
 

net/tap_int.h

@@ -26,7 +26,6 @@
 #ifndef NET_TAP_INT_H
 #define NET_TAP_INT_H
 
-#include "qapi/qapi-types-net.h"
 #include "net/net.h"
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
@@ -34,7 +33,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
 
 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen);
 
-bool tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp);
+bool tap_set_sndbuf(int fd, int sndbuf, Error **errp);
 int tap_probe_vnet_hdr(int fd, Error **errp);
 int tap_probe_has_ufo(int fd);
 int tap_probe_has_uso(int fd);