Move flow use cnt to atomic and outside of the flow mutex protection.

src/app-layer.c

@@ -180,7 +180,7 @@ int AppLayerHandleMsg(AlpProtoDetectThreadCtx *dp_ctx, StreamMsg *smsg)
     }
 
     /* flow is free again */
-    smsg->flow->use_cnt--;
+    FlowDecrUsecnt(smsg->flow);
 
     /* return the used message to the queue */
     StreamMsgReturnToPool(smsg);

src/detect-engine-state.c

@@ -853,7 +853,7 @@ static int DeStateTest04(void) {
 
     result = 1;
 end:
-    CLEAR_FLOW(&f);
+    FLOW_DESTROY(&f);
 
     if (det_ctx != NULL) {
         DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);

src/detect.c

@@ -514,8 +514,9 @@ int SigMatchSignatures(ThreadVars *th_v, DetectEngineCtx *de_ctx, DetectEngineTh
 
     /* grab the protocol state we will detect on */
     if (p->flow != NULL) {
+        FlowIncrUsecnt(p->flow);
+
         SCMutexLock(&p->flow->m);
-        p->flow->use_cnt++;
         alstate = AppLayerGetProtoStateFromPacket(p);
         alproto = AppLayerGetProtoFromPacket(p);
         if (p->flowflags & FLOW_PKT_TOSERVER && p->flow->flags & FLOW_SGH_TOSERVER) {
@@ -853,8 +854,9 @@ end:
             p->flow->sgh_toclient = det_ctx->sgh;
             p->flow->flags |= FLOW_SGH_TOCLIENT;
         }
-        p->flow->use_cnt--;
         SCMutexUnlock(&p->flow->m);
+
+        FlowDecrUsecnt(p->flow);
     }
 
     SCReturnInt(fmatch);

src/flow-hash.c

@@ -28,7 +28,7 @@
 #include "threads.h"
 
 #include "decode.h"
-#include "debug.h"
+#include "detect-engine-state.h"
 
 #include "flow.h"
 #include "flow-hash.h"
@@ -345,11 +345,16 @@ static Flow *FlowGetNew(Packet *p) {
             return NULL;
         }
 
-        /* f is locked */
+        /* flow is initialized but *unlocked* */
     } else {
-        SCMutexLock(&f->m);
+        FLOW_RECYCLE(f);
+
+        /* flow is initialized (recylced) but *unlocked* */
     }
 
+    FlowIncrUsecnt(f);
+
+    SCMutexLock(&f->m);
     return f;
 }
 
@@ -391,16 +396,13 @@ Flow *FlowGetFlowFromHash (Packet *p)
 
         /* flow is locked */
 
-        /* these are protected by the bucket lock */
-        f->hnext = NULL;
-        f->hprev = NULL;
-
         /* got one, now lock, initialize and return */
         FlowInit(f,p);
-        FlowRequeue(f, NULL, &flow_new_q[f->protomap], 1);
         f->flags |= FLOW_NEW_LIST;
         f->fb = fb;
 
+        FlowRequeue(f, NULL, &flow_new_q[f->protomap], 1);
+
         SCSpinUnlock(&fb->s);
         FlowHashCountUpdate;
         return f;
@@ -429,16 +431,16 @@ Flow *FlowGetFlowFromHash (Packet *p)
 
                 /* flow is locked */
 
-                f->hnext = NULL;
                 f->hprev = pf;
 
                 /* initialize and return */
                 FlowInit(f,p);
-                FlowRequeue(f, NULL, &flow_new_q[f->protomap], 1);
 
                 f->flags |= FLOW_NEW_LIST;
                 f->fb = fb;
 
+                FlowRequeue(f, NULL, &flow_new_q[f->protomap], 1);
+
                 SCSpinUnlock(&fb->s);
                 FlowHashCountUpdate;
                 return f;
@@ -455,7 +457,8 @@ Flow *FlowGetFlowFromHash (Packet *p)
                 fb->f->hprev = f;
                 fb->f = f;
 
-                /* found our flow */
+                /* found our flow, lock & return */
+                FlowIncrUsecnt(f);
                 SCMutexLock(&f->m);
                 SCSpinUnlock(&fb->s);
                 FlowHashCountUpdate;
@@ -464,10 +467,9 @@ Flow *FlowGetFlowFromHash (Packet *p)
         }
     }
 
-    if (f != NULL) {
-        SCMutexLock(&f->m);
-    }
-
+    /* lock & return */
+    FlowIncrUsecnt(f);
+    SCMutexLock(&f->m);
     SCSpinUnlock(&fb->s);
     FlowHashCountUpdate;
     return f;

src/flow-util.c

@@ -37,7 +37,13 @@
 #include "detect.h"
 #include "detect-engine-state.h"
 
-/* Allocate a flow */
+/** \brief allocate a flow
+ *
+ *  We check against the memuse counter. If it passes that check we increment
+ *  the counter first, then we try to alloc.
+ *
+ *  \retval f the flow or NULL on out of memory
+ */
 Flow *FlowAlloc(void)
 {
     Flow *f;
@@ -46,27 +52,29 @@ Flow *FlowAlloc(void)
         return NULL;
     }
 
+    SC_ATOMIC_ADD(flow_memuse, sizeof(Flow));
+
     f = SCMalloc(sizeof(Flow));
     if (f == NULL) {
+        SC_ATOMIC_SUB(flow_memuse, sizeof(Flow));
         return NULL;
     }
 
-    SC_ATOMIC_ADD(flow_memuse, sizeof(Flow));
 
-    SCMutexInit(&f->m, NULL);
-    f->lnext = NULL;
-    f->lprev = NULL;
-    f->hnext = NULL;
-    f->hprev = NULL;
+    FLOW_INITIALIZE(f);
 
     return f;
 }
 
 
-/** free the memory of a flow */
+/**
+ *  \brief cleanup & free the memory of a flow
+ *
+ *  \param f flow to clear & destroy
+ */
 void FlowFree(Flow *f)
 {
-    SCMutexDestroy(&f->m);
+    FLOW_DESTROY(f);
     SCFree(f);
 
     SC_ATOMIC_SUB(flow_memuse, sizeof(Flow));
@@ -99,10 +107,6 @@ void FlowInit(Flow *f, Packet *p)
     SCEnter();
     SCLogDebug("flow %p", f);
 
-    f->flowvar = NULL;
-    f->de_state = NULL;
-    CLEAR_FLOW(f);
-
     f->proto = p->proto;
     f->recursion_level = p->recursion_level;
 

src/flow-util.h

@@ -26,26 +26,60 @@
 
 #define COPY_TIMESTAMP(src,dst) ((dst)->tv_sec = (src)->tv_sec, (dst)->tv_usec = (src)->tv_usec)
 
-/* only clear the parts that won't be overwritten
- * in FlowInit anyway */
-#define CLEAR_FLOW(f) { \
-    (f)->sp = 0; \
-    (f)->dp = 0; \
-    (f)->flags = 0; \
-    (f)->todstpktcnt = 0; \
-    (f)->tosrcpktcnt = 0; \
-    (f)->bytecnt = 0; \
-    (f)->lastts.tv_sec = 0; \
-    (f)->lastts.tv_usec = 0; \
-    GenericVarFree((f)->flowvar); \
-    (f)->flowvar = NULL; \
-    (f)->protoctx = NULL; \
-    (f)->use_cnt = 0; \
-    DetectEngineStateFree((f)->de_state); \
-    (f)->de_state = NULL; \
-    (f)->sgh_toserver = NULL; \
-    (f)->sgh_toclient = NULL; \
-}
+#define FLOW_INITIALIZE(f) do { \
+        SCMutexInit(&(f)->m, NULL); \
+        (f)->lnext = NULL; \
+        (f)->lprev = NULL; \
+        (f)->hnext = NULL; \
+        (f)->hprev = NULL; \
+        (f)->sp = 0; \
+        (f)->dp = 0; \
+        (f)->flags = 0; \
+        (f)->todstpktcnt = 0; \
+        (f)->tosrcpktcnt = 0; \
+        (f)->bytecnt = 0; \
+        (f)->lastts.tv_sec = 0; \
+        (f)->lastts.tv_usec = 0; \
+        (f)->flowvar = NULL; \
+        (f)->protoctx = NULL; \
+        SC_ATOMIC_INIT((f)->use_cnt); \
+        (f)->de_state = NULL; \
+        (f)->sgh_toserver = NULL; \
+        (f)->sgh_toclient = NULL; \
+    } while (0)
+
+#define FLOW_RECYCLE(f) do { \
+        (f)->lnext = NULL; \
+        (f)->lprev = NULL; \
+        (f)->hnext = NULL; \
+        (f)->hprev = NULL; \
+        (f)->sp = 0; \
+        (f)->dp = 0; \
+        (f)->flags = 0; \
+        (f)->todstpktcnt = 0; \
+        (f)->tosrcpktcnt = 0; \
+        (f)->bytecnt = 0; \
+        (f)->lastts.tv_sec = 0; \
+        (f)->lastts.tv_usec = 0; \
+        GenericVarFree((f)->flowvar); \
+        (f)->flowvar = NULL; \
+        (f)->protoctx = NULL; \
+        SC_ATOMIC_RESET((f)->use_cnt); \
+        DetectEngineStateFree((f)->de_state); \
+        (f)->de_state = NULL; \
+        (f)->sgh_toserver = NULL; \
+        (f)->sgh_toclient = NULL; \
+    } while(0)
+
+#define FLOW_DESTROY(f) do { \
+        SCMutexDestroy(&(f)->m); \
+        GenericVarFree((f)->flowvar); \
+        (f)->flowvar = NULL; \
+        (f)->protoctx = NULL; \
+        SC_ATOMIC_DESTROY((f)->use_cnt); \
+        DetectEngineStateFree((f)->de_state); \
+        (f)->de_state = NULL; \
+    } while(0)
 
 Flow *FlowAlloc(void);
 Flow *FlowAllocDirect(void);

src/flow.c

@@ -228,14 +228,17 @@ static int FlowPrune (FlowQueue *q, struct timeval *ts)
 
     /** never prune a flow that is used by a packet or stream msg
      *  we are currently processing in one of the threads */
-    if (f->use_cnt > 0) {
-        SCLogDebug("timed out but use_cnt > 0: %"PRIu16", %p, proto %"PRIu8"", f->use_cnt, f, f->proto);
+    if (SC_ATOMIC_GET(f->use_cnt) > 0) {
+        SCLogDebug("timed out but use_cnt > 0: %"PRIu16", %p, proto %"PRIu8"", SC_ATOMIC_GET(f->use_cnt), f, f->proto);
         SCSpinUnlock(&f->fb->s);
         SCMutexUnlock(&f->m);
         SCLogDebug("it is in one of the threads");
         return 0;
     }
 
+    /* this should not be possible */
+    BUG_ON(SC_ATOMIC_GET(f->use_cnt) > 0);
+
     /* remove from the hash */
     if (f->hprev)
         f->hprev->hnext = f->hnext;
@@ -378,7 +381,7 @@ int FlowKill (FlowQueue *q)
 
         /** never prune a flow that is used by a packet or stream msg
          *  we are currently processing in one of the threads */
-        if (f->use_cnt > 0) {
+        if (SC_ATOMIC_GET(f->use_cnt) > 0) {
             SCSpinUnlock(&f->fb->s);
             SCMutexUnlock(&f->m);
             f = f->lnext;
@@ -549,30 +552,27 @@ void FlowSetIPOnlyFlagNoLock(Flow *f, char direction) {
     direction ? (f->flags |= FLOW_TOSERVER_IPONLY_SET) : (f->flags |= FLOW_TOCLIENT_IPONLY_SET);
 }
 
-/** \brief increase the use cnt of a flow
- *  \param tv thread vars (\todo unused?)
- *  \param p packet with flow to decrease use cnt for
+/**
+ *  \brief increase the use cnt of a flow
+ *
+ *  \param f flow to decrease use cnt for
  */
-void FlowIncrUsecnt(ThreadVars *tv, Packet *p) {
-    if (p == NULL || p->flow == NULL)
+void FlowIncrUsecnt(Flow *f) {
+    if (f == NULL)
         return;
 
-    SCMutexLock(&p->flow->m);
-    p->flow->use_cnt++;
-    SCMutexUnlock(&p->flow->m);
+    SC_ATOMIC_ADD(f->use_cnt, 1);
 }
-/** \brief decrease the use cnt of a flow
- *  \param tv thread vars (\todo unused?)
- *  \param p packet with flow to decrease use cnt for
+/**
+ *  \brief decrease the use cnt of a flow
+ *
+ *  \param f flow to decrease use cnt for
  */
-void FlowDecrUsecnt(ThreadVars *tv, Packet *p) {
-    if (p == NULL || p->flow == NULL)
+void FlowDecrUsecnt(Flow *f) {
+    if (f == NULL)
         return;
 
-    SCMutexLock(&p->flow->m);
-    if (p->flow->use_cnt > 0)
-        p->flow->use_cnt--;
-    SCMutexUnlock(&p->flow->m);
+    SC_ATOMIC_SUB(f->use_cnt, 1);
 }
 
 #define TOSERVER 0
@@ -645,8 +645,6 @@ void FlowHandlePacket (ThreadVars *tv, Packet *p)
     if (f == NULL)
         return;
 
-    f->use_cnt++;
-
     /* update the last seen timestamp of this flow */
     COPY_TIMESTAMP(&p->ts, &f->lastts);
 
@@ -1308,7 +1306,7 @@ static int FlowClearMemory(Flow* f, uint8_t proto_map) {
         flow_proto[proto_map].Freefunc(f->protoctx);
     }
 
-    CLEAR_FLOW(f);
+    FLOW_DESTROY(f);
 
     SCReturnInt(1);
 }
@@ -1553,6 +1551,7 @@ static int FlowTestPrune(Flow *f, struct timeval *ts) {
         goto error;
     }
 
+    SCLogDebug("calling FlowPrune");
     FlowPrune(q, ts);
     if (q->len != 0) {
         printf("Failed in prunning the flow: ");
@@ -1593,7 +1592,8 @@ static int FlowTest03 (void) {
     memset(&fb, 0, sizeof(FlowBucket));
 
     SCSpinInit(&fb.s, 0);
-    SCMutexInit(&f.m, NULL);
+
+    FLOW_INITIALIZE(&f);
 
     TimeGet(&ts);
     f.lastts.tv_sec = ts.tv_sec - 5000;

src/flow.h

@@ -26,6 +26,7 @@
 
 #include "decode.h"
 #include "util-var.h"
+#include "util-atomic.h"
 
 #define FLOW_QUIET      TRUE
 #define FLOW_VERBOSE    FALSE
@@ -159,8 +160,13 @@ typedef struct Flow_
     /** protocol specific data pointer, e.g. for TcpSession */
     void *protoctx;
 
-    /** how many pkts and stream msgs are using the flow *right now* */
-    uint16_t use_cnt;
+    /** how many pkts and stream msgs are using the flow *right now*. This
+     *  variable is atomic so not protected by the Flow mutex "m".
+     *
+     *  On receiving a packet the counter is incremented while the flow
+     *  bucked is locked, which is also the case on timeout pruning.
+     */
+    SC_ATOMIC_DECLARE(unsigned short, use_cnt);
 
     /** detection engine state */
     struct DetectEngineState_ *de_state;
@@ -208,7 +214,10 @@ void FlowPrintQueueInfo (void);
 void FlowShutdown(void);
 void FlowSetIPOnlyFlag(Flow *, char);
 void FlowSetIPOnlyFlagNoLock(Flow *, char);
-void FlowDecrUsecnt(ThreadVars *, Packet *);
+
+void FlowIncrUsecnt(Flow *);
+void FlowDecrUsecnt(Flow *);
+
 uint32_t FlowPruneFlowsCnt(struct timeval *, int);
 uint32_t FlowKillFlowsCnt(int);
 

src/stream-tcp-reassemble.c

@@ -1295,9 +1295,8 @@ static void StreamTcpSetupMsg(TcpSession *ssn, TcpStream *stream, Packet *p,
 
     smsg->data.data_len = 0;
     smsg->flow = p->flow;
-    if (smsg->flow != NULL) {
-        smsg->flow->use_cnt++;
-    }
+
+    FlowIncrUsecnt(smsg->flow);
 
     SCLogDebug("smsg %p", smsg);
     SCReturn;

src/tmqh-packetpool.c

@@ -133,7 +133,7 @@ void TmqhOutputPacketpool(ThreadVars *t, Packet *p)
         SCLogDebug("tunnel stuff done, move on (proot %d)", proot);
     }
 
-    FlowDecrUsecnt(t,p);
+    FlowDecrUsecnt(p->flow);
 
     /* we're done with the tunnel root now as well */
     if (proot == 1) {

src/util-atomic.h

@@ -67,14 +67,25 @@
  *  \brief Initialize the previously declared atomic variable and it's
  *         lock.
  */
-#define SC_ATOMIC_INIT(name) \
-    SCSpinInit(&(name ## _sc_lock__), 0)
+#define SC_ATOMIC_INIT(name) do { \
+        SCSpinInit(&(name ## _sc_lock__), 0); \
+        (name ## _sc_atomic__) = 0; \
+    } while(0)
+
+/**
+ *  \brief Initialize the previously declared atomic variable and it's
+ *         lock.
+ */
+#define SC_ATOMIC_RESET(name) do { \
+        (name ## _sc_atomic__) = 0; \
+    } while(0)
 
 /**
  *  \brief Destroy the lock used to protect this variable
  */
-#define SC_ATOMIC_DESTROY(name) \
-    SCSpinDestroy(&(name ## _sc_lock__))
+#define SC_ATOMIC_DESTROY(name) do { \
+        SCSpinDestroy(&(name ## _sc_lock__)); \
+    } while (0)
 
 /**
  *  \brief add a value to our atomic variable
@@ -200,6 +211,12 @@
 #define SC_ATOMIC_INIT(name) \
     (name ## _sc_atomic__) = 0
 
+/**
+ *  \brief wrapper for reinitializing an atomic variable.
+ **/
+#define SC_ATOMIC_RESET(name) \
+    (name ## _sc_atomic__) = 0
+
 /**
  *  \brief No-op.
  */

src/util-unittest-helper.c

@@ -702,7 +702,7 @@ uint32_t UTHBuildPacketOfFlows(uint32_t start, uint32_t end, uint8_t dir) {
         }
         FlowHandlePacket(NULL, p);
         if (p->flow != NULL)
-            p->flow->use_cnt = 0;
+            SC_ATOMIC_RESET(p->flow->use_cnt);
 
         /* Now the queues shoul be updated */
         UTHFreePacket(p);