pfring pkt acq: use zero-copy recv in workers runmode

This patch removes packet copy when suricata is running in workers runmode,
packet copy is not needed in this case since packets are processed in sequence.

src/source-pfring.c

@@ -125,6 +125,10 @@ static SCMutex pfring_bpf_set_filter_lock = SCMUTEX_INITIALIZER;
 #define LIBPFRING_REENTRANT   0
 #define LIBPFRING_WAIT_FOR_INCOMING 1
 
+typedef enum {
+    PFRING_FLAGS_ZERO_COPY = 0x1
+} PfringThreadVarsFlags;
+
 /**
  * \brief Structure to hold thread specific variables.
  */
@@ -140,6 +144,8 @@ typedef struct PfringThreadVars_
     uint16_t capture_kernel_packets;
     uint16_t capture_kernel_drops;
 
+    uint32_t flags;
+
     ThreadVars *tv;
     TmSlot *slot;
 
@@ -296,6 +302,8 @@ TmEcode ReceivePfringLoop(ThreadVars *tv, void *data, void *slot)
     TmSlot *s = (TmSlot *)slot;
     time_t last_dump = 0;
     struct timeval current_time;
+    u_int buffer_size;
+    u_char *pkt_buffer;
 
     ptv->slot = s->slot_next;
 
@@ -325,16 +333,23 @@ TmEcode ReceivePfringLoop(ThreadVars *tv, void *data, void *slot)
         /* Some flavours of PF_RING may fail to set timestamp - see PF-RING-enabled libpcap code*/
         hdr.ts.tv_sec = hdr.ts.tv_usec = 0;
 
+        /* Check for Zero-copy mode */
+        if (ptv->flags & PFRING_FLAGS_ZERO_COPY) {
+            buffer_size = 0;
+            pkt_buffer = NULL;
+        } else {
+            buffer_size = GET_PKT_DIRECT_MAX_SIZE(p);
+            pkt_buffer = GET_PKT_DIRECT_DATA(p);
+        }
+
         /* Depending on what compile time options are used for pfring we either return 0 or -1 on error and always 1 for success */
-        u_char *pkt_buffer = GET_PKT_DIRECT_DATA(p);
-        u_int buffer_size = GET_PKT_DIRECT_MAX_SIZE(p);
         int r = pfring_recv(ptv->pd, &pkt_buffer,
                 buffer_size,
                 &hdr,
                 LIBPFRING_WAIT_FOR_INCOMING);
 
-        /* Check for Zero-copy if buffer size is zero */
-        if (buffer_size == 0) {
+        /* Check for Zero-copy mode */
+        if (ptv->flags & PFRING_FLAGS_ZERO_COPY) {
             PacketSetData(p, pkt_buffer, hdr.caplen);
         }
 
@@ -386,7 +401,7 @@ TmEcode ReceivePfringThreadInit(ThreadVars *tv, void *initdata, void **data)
     u_int32_t version = 0;
     PfringIfaceConfig *pfconf = (PfringIfaceConfig *) initdata;
     unsigned int opflag;
-
+    char const *active_runmode = RunmodeGetActive();
 
     if (pfconf == NULL)
         return TM_ECODE_FAILED;
@@ -415,6 +430,12 @@ TmEcode ReceivePfringThreadInit(ThreadVars *tv, void *initdata, void **data)
         SCReturnInt(TM_ECODE_FAILED);
     }
 
+    /* enable zero-copy mode for workers runmode */
+    if (active_runmode && strcmp("workers", active_runmode) == 0) {
+        ptv->flags |= PFRING_FLAGS_ZERO_COPY;
+        SCLogInfo("Enabling zero-copy for %s", ptv->interface);
+    }
+
     ptv->checksum_mode = pfconf->checksum_mode;
 
     opflag = PF_RING_REENTRANT | PF_RING_PROMISC;