slirp: Allocate/free stack instance dynamically

Allocate the internal slirp state dynamically and provide and call
slirp_cleanup to properly release it after use. This patch finally
unbreaks slirp release and re-instantiation via host_net_* monitor
commands.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

net.c

@@ -729,11 +729,13 @@ static ssize_t slirp_receive(VLANClientState *vc, const uint8_t *buf, size_t siz
     return size;
 }
 
-static int slirp_in_use;
-
 static void net_slirp_cleanup(VLANClientState *vc)
 {
-    slirp_in_use = 0;
+    SlirpState *s = vc->opaque;
+
+    slirp_cleanup(s->slirp);
+    slirp_state = NULL;
+    qemu_free(s);
 }
 
 static int net_slirp_init(Monitor *mon, VLANState *vlan, const char *model,
@@ -744,13 +746,6 @@ static int net_slirp_init(Monitor *mon, VLANState *vlan, const char *model,
                           const char *vnameserver, const char *smb_export,
                           const char *vsmbserver)
 {
-    SlirpState *s = slirp_state;
-
-    if (slirp_in_use) {
-        /* slirp only supports a single instance so far */
-        return -1;
-    }
-    if (!s) {
     /* default settings according to historic slirp */
     struct in_addr net  = { .s_addr = htonl(0x0a000000) }; /* 10.0.0.0 */
     struct in_addr mask = { .s_addr = htonl(0xff000000) }; /* 255.0.0.0 */
@@ -760,6 +755,7 @@ static int net_slirp_init(Monitor *mon, VLANState *vlan, const char *model,
 #ifndef _WIN32
     struct in_addr smbsrv = { .s_addr = 0 };
 #endif
+    SlirpState *s;
     char buf[20];
     uint32_t addr;
     int shift;
@@ -869,12 +865,10 @@ static int net_slirp_init(Monitor *mon, VLANState *vlan, const char *model,
         slirp_smb(s, smb_export, smbsrv);
     }
 #endif
-    }
 
     s->vc = qemu_new_vlan_client(vlan, model, name, NULL, slirp_receive, NULL,
                                  net_slirp_cleanup, s);
     s->vc->info_str[0] = '\0';
-    slirp_in_use = 1;
     return 0;
 }
 

slirp/libslirp.h

@@ -13,6 +13,7 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
                   const char *vhostname, const char *tftp_path,
                   const char *bootfile, struct in_addr vdhcp_start,
                   struct in_addr vnameserver, void *opaque);
+void slirp_cleanup(Slirp *slirp);
 
 void slirp_select_fill(int *pnfds,
                        fd_set *readfds, fd_set *writefds, fd_set *xfds);

slirp/main.h

@@ -11,7 +11,6 @@
 
 #define TOWRITEMAX 512
 
-extern int link_up;
 extern int slirp_socket;
 extern int slirp_socket_unit;
 extern int slirp_socket_port;

slirp/slirp.c

@@ -40,8 +40,6 @@ static const uint8_t special_ethaddr[6] = {
 
 static const uint8_t zero_ethaddr[6] = { 0, 0, 0, 0, 0, 0 };
 
-int link_up; // FIXME: kill this
-
 /* XXX: suppress those select globals */
 fd_set *global_readfds, *global_writefds, *global_xfds;
 
@@ -49,7 +47,7 @@ u_int curtime;
 static u_int time_fasttimo, last_slowtimo;
 static int do_slowtimo;
 
-Slirp slirp_instance;
+Slirp *slirp_instance;
 
 #ifdef _WIN32
 
@@ -193,11 +191,10 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
                   const char *bootfile, struct in_addr vdhcp_start,
                   struct in_addr vnameserver, void *opaque)
 {
-    Slirp *slirp = &slirp_instance;
+    Slirp *slirp = qemu_mallocz(sizeof(Slirp));
 
     slirp_init_once();
 
-    link_up = 1;
     slirp->restricted = restricted;
 
     if_init(slirp);
@@ -213,13 +210,9 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
         pstrcpy(slirp->client_hostname, sizeof(slirp->client_hostname),
                 vhostname);
     }
-    qemu_free(slirp->tftp_prefix);
-    slirp->tftp_prefix = NULL;
     if (tftp_path) {
         slirp->tftp_prefix = qemu_strdup(tftp_path);
     }
-    qemu_free(slirp->bootp_filename);
-    slirp->bootp_filename = NULL;
     if (bootfile) {
         slirp->bootp_filename = qemu_strdup(bootfile);
     }
@@ -230,9 +223,22 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
 
     register_savevm("slirp", 0, 2, slirp_state_save, slirp_state_load, slirp);
 
+    slirp_instance = slirp;
+
     return slirp;
 }
 
+void slirp_cleanup(Slirp *slirp)
+{
+    unregister_savevm("slirp", slirp);
+
+    qemu_free(slirp->tftp_prefix);
+    qemu_free(slirp->bootp_filename);
+    qemu_free(slirp);
+
+    slirp_instance = NULL;
+}
+
 #define CONN_CANFSEND(so) (((so)->so_state & (SS_FCANTSENDMORE|SS_ISFCONNECTED)) == SS_ISFCONNECTED)
 #define CONN_CANFRCV(so) (((so)->so_state & (SS_FCANTRCVMORE|SS_ISFCONNECTED)) == SS_ISFCONNECTED)
 #define UPD_NFDS(x) if (nfds < (x)) nfds = (x)
@@ -263,11 +269,11 @@ static void updtime(void)
 void slirp_select_fill(int *pnfds,
                        fd_set *readfds, fd_set *writefds, fd_set *xfds)
 {
-    Slirp *slirp = &slirp_instance;
+    Slirp *slirp = slirp_instance;
     struct socket *so, *so_next;
     int nfds;
 
-    if (!link_up) {
+    if (!slirp_instance) {
         return;
     }
 
@@ -384,11 +390,11 @@ void slirp_select_fill(int *pnfds,
 void slirp_select_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds,
                        int select_error)
 {
-    Slirp *slirp = &slirp_instance;
+    Slirp *slirp = slirp_instance;
     struct socket *so, *so_next;
     int ret;
 
-    if (!link_up) {
+    if (!slirp_instance) {
         return;
     }
 

slirp/slirp.h

@@ -259,7 +259,7 @@ struct Slirp {
     void *opaque;
 };
 
-extern Slirp slirp_instance;
+extern Slirp *slirp_instance;
 
 #ifndef NULL
 #define NULL (void *)0