[Qemu-devel] [PATCH] net: Disable netmap backend when not supported

[Vincenzo Maffione]

This patch fixes configure so that netmap is not compiled in if the
host doesn't support an API version >= 11.

Moreover, some modifications have been done to net/netmap.c in
order to reflect the current netmap API (11).

Signed-off-by: Vincenzo Maffione <address@hidden>
---
 configure    |  3 +++
 net/netmap.c | 57 ++++++++++++++-------------------------------------------
 2 files changed, 17 insertions(+), 43 deletions(-)

diff --git a/configure b/configure
index 88133a1..61eb932 100755
--- a/configure
+++ b/configure
@@ -2118,6 +2118,9 @@ if test "$netmap" != "no" ; then
 #include <net/if.h>
 #include <net/netmap.h>
 #include <net/netmap_user.h>
+#if (NETMAP_API < 11) || (NETMAP_API > 15)
+#error
+#endif
 int main(void) { return 0; }
 EOF
   if compile_prog "" "" ; then
diff --git a/net/netmap.c b/net/netmap.c
index 0ccc497..8a67322 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -27,6 +27,8 @@
 #include <net/if.h>
 #include <sys/mman.h>
 #include <stdint.h>
+#include <stdio.h>
+#define NETMAP_WITH_LIBS
 #include <net/netmap.h>
 #include <net/netmap_user.h>
 
@@ -56,31 +58,6 @@ typedef struct NetmapState {
     struct iovec        iov[IOV_MAX];
 } NetmapState;
 
-#define D(format, ...)                                          \
-    do {                                                        \
-        struct timeval __xxts;                                  \
-        gettimeofday(&__xxts, NULL);                            \
-        printf("%03d.%06d %s [%d] " format "\n",                \
-                (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
-                __func__, __LINE__, ##__VA_ARGS__);         \
-    } while (0)
-
-/* Rate limited version of "D", lps indicates how many per second */
-#define RD(lps, format, ...)                                    \
-    do {                                                        \
-        static int t0, __cnt;                                   \
-        struct timeval __xxts;                                  \
-        gettimeofday(&__xxts, NULL);                            \
-        if (t0 != __xxts.tv_sec) {                              \
-            t0 = __xxts.tv_sec;                                 \
-            __cnt = 0;                                          \
-        }                                                       \
-        if (__cnt++ < lps) {                                    \
-            D(format, ##__VA_ARGS__);                           \
-        }                                                       \
-    } while (0)
-
-
 #ifndef __FreeBSD__
 #define pkt_copy bcopy
 #else
@@ -237,7 +214,7 @@ static ssize_t netmap_receive(NetClientState *nc,
         return size;
     }
 
-    if (ring->avail == 0) {
+    if (nm_ring_empty(ring)) {
         /* No available slots in the netmap TX ring. */
         netmap_write_poll(s, true);
         return 0;
@@ -250,8 +227,7 @@ static ssize_t netmap_receive(NetClientState *nc,
     ring->slot[i].len = size;
     ring->slot[i].flags = 0;
     pkt_copy(buf, dst, size);
-    ring->cur = NETMAP_RING_NEXT(ring, i);
-    ring->avail--;
+    ring->cur = ring->head = nm_ring_next(ring, i);
     ioctl(s->me.fd, NIOCTXSYNC, NULL);
 
     return size;
@@ -267,17 +243,15 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
     uint8_t *dst;
     int j;
     uint32_t i;
-    uint32_t avail;
 
     if (unlikely(!ring)) {
         /* Drop the packet. */
         return iov_size(iov, iovcnt);
     }
 
-    i = ring->cur;
-    avail = ring->avail;
+    last = i = ring->cur;
 
-    if (avail < iovcnt) {
+    if (nm_ring_space(ring) < iovcnt) {
         /* Not enough netmap slots. */
         netmap_write_poll(s, true);
         return 0;
@@ -293,7 +267,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
         while (iov_frag_size) {
             nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
 
-            if (unlikely(avail == 0)) {
+            if (unlikely(nm_ring_empty(ring))) {
                 /* We run out of netmap slots while splitting the
                    iovec fragments. */
                 netmap_write_poll(s, true);
@@ -308,8 +282,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
             pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
 
             last = i;
-            i = NETMAP_RING_NEXT(ring, i);
-            avail--;
+            i = nm_ring_next(ring, i);
 
             offset += nm_frag_size;
             iov_frag_size -= nm_frag_size;
@@ -318,9 +291,8 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
     /* The last slot must not have NS_MOREFRAG set. */
     ring->slot[last].flags &= ~NS_MOREFRAG;
 
-    /* Now update ring->cur and ring->avail. */
-    ring->cur = i;
-    ring->avail = avail;
+    /* Now update ring->cur and ring->head. */
+    ring->cur = ring->head = i;
 
     ioctl(s->me.fd, NIOCTXSYNC, NULL);
 
@@ -343,7 +315,7 @@ static void netmap_send(void *opaque)
 
     /* Keep sending while there are available packets into the netmap
        RX ring and the forwarding path towards the peer is open. */
-    while (ring->avail > 0 && qemu_can_send_packet(&s->nc)) {
+    while (!nm_ring_empty(ring) && qemu_can_send_packet(&s->nc)) {
         uint32_t i;
         uint32_t idx;
         bool morefrag;
@@ -358,11 +330,10 @@ static void netmap_send(void *opaque)
             s->iov[iovcnt].iov_len = ring->slot[i].len;
             iovcnt++;
 
-            ring->cur = NETMAP_RING_NEXT(ring, i);
-            ring->avail--;
-        } while (ring->avail && morefrag);
+            ring->cur = ring->head = nm_ring_next(ring, i);
+        } while (!nm_ring_empty(ring) && morefrag);
 
-        if (unlikely(!ring->avail && morefrag)) {
+        if (unlikely(nm_ring_empty(ring) && morefrag)) {
             RD(5, "[netmap_send] ran out of slots, with a pending"
                    "incomplete packet\n");
         }
-- 
1.8.5.4