Merged in dstaesse/ouroboros/be-fp (pull request #261)

lib: Track SDUs in the fast path

3 files changed, 174 insertions, 88 deletions

diff --git a/src/lib/dev.c b/src/lib/dev.c
index e20d23d4..c1f769ad 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -356,6 +356,8 @@ int flow_accept(char ** ae_name)
         ai.ports[recv_msg->port_id].fd    = fd;
         ai.ports[recv_msg->port_id].state = PORT_ID_ASSIGNED;
 
+        shm_ap_rbuff_open_port(ai.rb, recv_msg->port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -478,6 +480,8 @@ int flow_alloc(char * dst_name, char * src_ae_name, struct qos_spec * qos)
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
+        shm_ap_rbuff_open_port(ai.rb, recv_msg->port_id);
+
         irm_msg__free_unpacked(recv_msg, NULL);
 
         return fd;
@@ -559,6 +563,8 @@ int flow_dealloc(int fd)
 
         bmp_release(ai.fds, fd);
 
+        shm_ap_rbuff_close_port(ai.rb, msg.port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
 
         send_irm_msg(&msg);
@@ -630,10 +636,10 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                                        DU_BUFF_TAILSPACE,
                                        buf,
                                        count);
-                if (idx == -1) {
+                if (idx < 0) {
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
-                        return -EAGAIN;
+                        return -idx;
                 }
 
                 e.index   = idx;
@@ -643,7 +649,7 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                         shm_rdrbuff_remove(ai.rdrb, idx);
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
-                        return -1;
+                        return -ENOTALLOC;
                 }
         } else { /* blocking */
                 struct shm_rdrbuff * rdrb = ai.rdrb;
@@ -664,8 +670,12 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                 e.index   = idx;
                 e.port_id = ai.flows[fd].port_id;
 
-                while (shm_ap_rbuff_write(ai.flows[fd].rb, &e) < 0)
-                        ;
+                if (shm_ap_rbuff_write(ai.flows[fd].rb, &e) < 0) {
+                        shm_rdrbuff_remove(ai.rdrb, e.index);
+                        pthread_rwlock_unlock(&ai.flows_lock);
+                        pthread_rwlock_unlock(&ai.data_lock);
+                        return -ENOTALLOC;
+                }
         }
 
         pthread_rwlock_unlock(&ai.flows_lock);
@@ -838,6 +848,8 @@ int np1_flow_alloc(pid_t n_api, int port_id)
         ai.ports[port_id].fd = fd;
         port_set_state(&ai.ports[port_id], PORT_ID_ASSIGNED);
 
+        shm_ap_rbuff_open_port(ai.rb, port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -867,6 +879,8 @@ int np1_flow_dealloc(int port_id)
 
         port_destroy(&ai.ports[port_id]);
 
+        shm_ap_rbuff_close_port(ai.rb, port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -902,6 +916,8 @@ int np1_flow_resp(pid_t n_api, int port_id)
 
         ai.flows[fd].rb = rb;
 
+        shm_ap_rbuff_open_port(ai.rb, port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -1011,6 +1027,9 @@ int ipcp_flow_alloc_reply(int fd, int response)
         msg.has_response = true;
         msg.response     = response;
 
+        if (response)
+                shm_ap_rbuff_open_port(ai.rb, msg.port_id);
+
         recv_msg = send_recv_irm_msg(&msg);
         if (recv_msg == NULL)
                 return -1;
diff --git a/src/lib/shm_ap_rbuff.c b/src/lib/shm_ap_rbuff.c
index acbc81a6..ede0b7f7 100644
--- a/src/lib/shm_ap_rbuff.c
+++ b/src/lib/shm_ap_rbuff.c
@@ -39,28 +39,33 @@
 #include <unistd.h>
 #include <signal.h>
 #include <sys/stat.h>
+#include <assert.h>
 
 #define FN_MAX_CHARS 255
 
 #define SHM_RBUFF_FILE_SIZE (SHM_BUFFER_SIZE * sizeof(struct rb_entry)         \
+                             + IRMD_MAX_FLOWS * sizeof(int8_t)                 \
+                             + IRMD_MAX_FLOWS * sizeof (ssize_t)               \
                              + 2 * sizeof(size_t) + sizeof(pthread_mutex_t)    \
                              + 2 * sizeof (pthread_cond_t))
 
-#define shm_rbuff_used(rb)((*rb->ptr_head + SHM_BUFFER_SIZE - *rb->ptr_tail)   \
+#define shm_rbuff_used(rb)((*rb->head + SHM_BUFFER_SIZE - *rb->tail)   \
                           & (SHM_BUFFER_SIZE - 1))
 #define shm_rbuff_free(rb)(shm_rbuff_used(rb) + 1 < SHM_BUFFER_SIZE)
-#define shm_rbuff_empty(rb) (*rb->ptr_head == *rb->ptr_tail)
-#define head_el_ptr(rb) (rb->shm_base + *rb->ptr_head)
-#define tail_el_ptr(rb) (rb->shm_base + *rb->ptr_tail)
+#define shm_rbuff_empty(rb) (*rb->head == *rb->tail)
+#define head_el_ptr(rb) (rb->shm_base + *rb->head)
+#define tail_el_ptr(rb) (rb->shm_base + *rb->tail)
 
 struct shm_ap_rbuff {
-        struct rb_entry * shm_base;    /* start of entry */
-        size_t *          ptr_head;    /* start of ringbuffer head */
-        size_t *          ptr_tail;    /* start of ringbuffer tail */
-        pthread_mutex_t * lock;        /* lock all free space in shm */
-        pthread_cond_t *  add;         /* SDU arrived */
-        pthread_cond_t *  del;         /* SDU removed */
-        pid_t             api;         /* api to which this rb belongs */
+        struct rb_entry * shm_base; /* start of entry                */
+        size_t *          head;     /* start of ringbuffer head      */
+        size_t *          tail;     /* start of ringbuffer tail      */
+        int8_t *          acl;      /* start of port_id access table */
+        ssize_t *         cntrs;    /* start of port_id counters     */
+        pthread_mutex_t * lock;     /* lock all free space in shm    */
+        pthread_cond_t *  add;      /* SDU arrived                   */
+        pthread_cond_t *  del;      /* SDU removed                   */
+        pid_t             api;      /* api to which this rb belongs  */
         int               fd;
 };
 
@@ -73,6 +78,7 @@ struct shm_ap_rbuff * shm_ap_rbuff_create()
         pthread_condattr_t    cattr;
         char                  fn[FN_MAX_CHARS];
         mode_t                mask;
+        int                   i;
 
         sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", getpid());
 
@@ -125,9 +131,11 @@ struct shm_ap_rbuff * shm_ap_rbuff_create()
         }
 
         rb->shm_base = shm_base;
-        rb->ptr_head = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
-        rb->ptr_tail = rb->ptr_head + 1;
-        rb->lock     = (pthread_mutex_t *) (rb->ptr_tail + 1);
+        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
+        rb->tail     = rb->head + 1;
+        rb->acl      = (int8_t *) (rb->tail + 1);
+        rb->cntrs    = (ssize_t *) (rb->acl + IRMD_MAX_FLOWS);
+        rb->lock     = (pthread_mutex_t *) (rb->cntrs + IRMD_MAX_FLOWS);
         rb->add      = (pthread_cond_t *) (rb->lock + 1);
         rb->del      = rb->add + 1;
 
@@ -143,11 +151,16 @@ struct shm_ap_rbuff * shm_ap_rbuff_create()
 #ifndef __APPLE__
         pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
 #endif
+        for (i = 0; i < IRMD_MAX_FLOWS; ++i) {
+                rb->cntrs[i] = 0;
+                rb->acl[i] = -1;
+        }
+
         pthread_cond_init(rb->add, &cattr);
         pthread_cond_init(rb->del, &cattr);
 
-        *rb->ptr_head = 0;
-        *rb->ptr_tail = 0;
+        *rb->head = 0;
+        *rb->tail = 0;
 
         rb->fd  = shm_fd;
         rb->api = getpid();
@@ -197,9 +210,11 @@ struct shm_ap_rbuff * shm_ap_rbuff_open(pid_t api)
         }
 
         rb->shm_base = shm_base;
-        rb->ptr_head = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
-        rb->ptr_tail = rb->ptr_head + 1;
-        rb->lock     = (pthread_mutex_t *) (rb->ptr_tail + 1);
+        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
+        rb->tail     = rb->head + 1;
+        rb->acl      = (int8_t *) (rb->tail + 1);
+        rb->cntrs    = (ssize_t *) (rb->acl + IRMD_MAX_FLOWS);
+        rb->lock     = (pthread_mutex_t *) (rb->cntrs + IRMD_MAX_FLOWS);
         rb->add      = (pthread_cond_t *) (rb->lock + 1);
         rb->del      = rb->add + 1;
 
@@ -211,10 +226,7 @@ struct shm_ap_rbuff * shm_ap_rbuff_open(pid_t api)
 
 void shm_ap_rbuff_close(struct shm_ap_rbuff * rb)
 {
-        if (rb == NULL) {
-                LOG_DBG("Bogus input. Bugging out.");
-                return;
-        }
+        assert(rb);
 
         if (close(rb->fd) < 0)
                 LOG_DBG("Couldn't close shared memory.");
@@ -225,15 +237,56 @@ void shm_ap_rbuff_close(struct shm_ap_rbuff * rb)
         free(rb);
 }
 
+void shm_ap_rbuff_open_port(struct shm_ap_rbuff * rb, int port_id)
+{
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+
+#ifdef OUROBOROS_CONFIG_DEBUG
+        if (!rb->acl[port_id])
+                LOG_DBG("Trying to open open port.");
+#endif
+        rb->acl[port_id] = 0; /* open */
+
+        pthread_mutex_unlock(rb->lock);
+}
+
+void shm_ap_rbuff_close_port(struct shm_ap_rbuff * rb, int port_id)
+{
+
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+#ifdef OUROBOROS_CONFIG_DEBUG
+        if (rb->acl[port_id])
+                LOG_DBG("Trying to close closed port.");
+#endif
+        rb->acl[port_id] = -1;
+
+        pthread_mutex_unlock(rb->lock);
+}
+
 void shm_ap_rbuff_destroy(struct shm_ap_rbuff * rb)
 {
         char fn[25];
         struct lockfile * lf = NULL;
 
-        if (rb == NULL) {
-                LOG_DBG("Bogus input. Bugging out.");
-                return;
-        }
+        assert(rb);
 
         if (rb->api != getpid()) {
                 lf = lockfile_open();
@@ -267,8 +320,8 @@ void shm_ap_rbuff_destroy(struct shm_ap_rbuff * rb)
 
 int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
 {
-        if (rb == NULL || e == NULL)
-                return -1;
+        assert(rb);
+        assert(e);
 
 #ifdef __APPLE__
         pthread_mutex_lock(rb->lock);
@@ -278,6 +331,11 @@ int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
                 pthread_mutex_consistent(rb->lock);
         }
 #endif
+        if (rb->acl[e->port_id]) {
+                pthread_mutex_unlock(rb->lock);
+                return -ENOTALLOC;
+        }
+
         if (!shm_rbuff_free(rb)) {
                 pthread_mutex_unlock(rb->lock);
                 return -1;
@@ -287,7 +345,9 @@ int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
                 pthread_cond_broadcast(rb->add);
 
         *head_el_ptr(rb) = *e;
-        *rb->ptr_head = (*rb->ptr_head + 1) & (SHM_BUFFER_SIZE -1);
+        *rb->head = (*rb->head + 1) & (SHM_BUFFER_SIZE -1);
+
+        ++rb->cntrs[e->port_id];
 
         pthread_mutex_unlock(rb->lock);
 
@@ -298,8 +358,8 @@ int shm_ap_rbuff_pop_idx(struct shm_ap_rbuff * rb)
 {
         int ret = 0;
 
-        if (rb == NULL)
-                return -EINVAL;
+        assert(rb);
+
 #ifdef __APPLE__
         pthread_mutex_lock(rb->lock);
 #else
@@ -314,8 +374,8 @@ int shm_ap_rbuff_pop_idx(struct shm_ap_rbuff * rb)
         }
 
         ret = tail_el_ptr(rb)->index;
-
-        *rb->ptr_head = (*rb->ptr_head + 1) & (SHM_BUFFER_SIZE -1);
+        --rb->cntrs[tail_el_ptr(rb)->port_id];
+        *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
 
         pthread_mutex_unlock(rb->lock);
 
@@ -328,8 +388,7 @@ static int shm_ap_rbuff_peek_b_all(struct shm_ap_rbuff * rb,
         struct timespec abstime;
         int ret = 0;
 
-        if (rb == NULL)
-                return -EINVAL;
+        assert(rb);
 
         if (timeout != NULL) {
                 clock_gettime(PTHREAD_COND_CLOCK, &abstime);
@@ -380,6 +439,8 @@ int shm_ap_rbuff_peek_b(struct shm_ap_rbuff *   rb,
         struct timespec abstime;
         int ret;
 
+        assert(rb);
+
         if (set == NULL)
                 return shm_ap_rbuff_peek_b_all(rb, timeout);
 
@@ -453,12 +514,10 @@ struct rb_entry * shm_ap_rbuff_read(struct shm_ap_rbuff * rb)
 {
         struct rb_entry * e = NULL;
 
-        if (rb == NULL)
-                return NULL;
+        assert(rb);
 
         pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
                              (void *) rb->lock);
-
 #ifdef __APPLE__
         pthread_mutex_lock(rb->lock);
 #else
@@ -478,8 +537,9 @@ struct rb_entry * shm_ap_rbuff_read(struct shm_ap_rbuff * rb)
 #endif
         e = malloc(sizeof(*e));
         if (e != NULL) {
-                *e = *(rb->shm_base + *rb->ptr_tail);
-                *rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_BUFFER_SIZE -1);
+                *e = *(rb->shm_base + *rb->tail);
+                --rb->cntrs[e->port_id];
+                *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
         }
 
         pthread_cleanup_pop(true);
@@ -499,14 +559,19 @@ ssize_t shm_ap_rbuff_read_port(struct shm_ap_rbuff * rb, int port_id)
                 pthread_mutex_consistent(rb->lock);
         }
 #endif
+        if (rb->acl[port_id]) {
+                pthread_mutex_unlock(rb->lock);
+                return -ENOTALLOC;
+        }
+
         if (shm_rbuff_empty(rb) || tail_el_ptr(rb)->port_id != port_id) {
                 pthread_mutex_unlock(rb->lock);
                 return -1;
         }
 
         idx = tail_el_ptr(rb)->index;
-
-        *rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_BUFFER_SIZE -1);
+        --rb->cntrs[port_id];
+        *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
 
         pthread_cond_broadcast(rb->del);
         pthread_mutex_unlock(rb->lock);
@@ -522,6 +587,8 @@ ssize_t shm_ap_rbuff_read_port_b(struct shm_ap_rbuff *   rb,
         int ret = 0;
         ssize_t idx = -1;
 
+        assert(rb);
+
 #ifdef __APPLE__
         pthread_mutex_lock(rb->lock);
 #else
@@ -530,7 +597,13 @@ ssize_t shm_ap_rbuff_read_port_b(struct shm_ap_rbuff *   rb,
                 pthread_mutex_consistent(rb->lock);
         }
 #endif
+        if (rb->acl[port_id]) {
+                pthread_mutex_unlock(rb->lock);
+                return -ENOTALLOC;
+        }
+
         if (timeout != NULL) {
+                idx = -ETIMEDOUT;
                 clock_gettime(PTHREAD_COND_CLOCK, &abstime);
                 ts_add(&abstime, timeout, &abstime);
         }
@@ -577,7 +650,8 @@ ssize_t shm_ap_rbuff_read_port_b(struct shm_ap_rbuff *   rb,
 
         if (ret != ETIMEDOUT) {
                 idx = tail_el_ptr(rb)->index;
-                *rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_BUFFER_SIZE -1);
+                  --rb->cntrs[port_id];
+                *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
 
                 pthread_cond_broadcast(rb->del);
         }
@@ -589,11 +663,10 @@ ssize_t shm_ap_rbuff_read_port_b(struct shm_ap_rbuff *   rb,
 
 void shm_ap_rbuff_reset(struct shm_ap_rbuff * rb)
 {
-        if (rb == NULL)
-                return;
+        assert(rb);
 
         pthread_mutex_lock(rb->lock);
-        *rb->ptr_tail = 0;
-        *rb->ptr_head = 0;
+        *rb->tail = 0;
+        *rb->head = 0;
         pthread_mutex_unlock(rb->lock);
 }
diff --git a/src/lib/shm_rdrbuff.c b/src/lib/shm_rdrbuff.c
index fb58a4d6..f6683dc2 100644
--- a/src/lib/shm_rdrbuff.c
+++ b/src/lib/shm_rdrbuff.c
@@ -35,6 +35,7 @@
 #include <signal.h>
 #include <sys/stat.h>
 #include <stdbool.h>
+#include <assert.h>
 
 #define OUROBOROS_PREFIX "shm_rdrbuff"
 
@@ -324,8 +325,8 @@ void * shm_rdrbuff_sanitize(void * o)
 
         pid_t   api;
 
-        if (rdrb == NULL)
-                return (void *) -1;
+        assert(o);
+
 #ifdef __APPLE__
         pthread_mutex_lock(rdrb->lock);
 #else
@@ -397,10 +398,7 @@ void * shm_rdrbuff_sanitize(void * o)
 
 void shm_rdrbuff_close(struct shm_rdrbuff * rdrb)
 {
-        if (rdrb == NULL) {
-                LOG_DBGF("Bogus input. Bugging out.");
-                return;
-        }
+        assert(rdrb);
 
         if (close(rdrb->fd) < 0)
                 LOG_DBGF("Couldn't close shared memory.");
@@ -415,10 +413,7 @@ void shm_rdrbuff_destroy(struct shm_rdrbuff * rdrb)
 {
         char * shm_rdrb_fn;
 
-        if (rdrb == NULL) {
-                LOG_DBGF("Bogus input. Bugging out.");
-                return;
-        }
+        assert(rdrb);
 
         if (getpid() != *rdrb->api && kill(*rdrb->api, 0) == 0) {
                 LOG_DBG("Process %d tried to destroy active rdrb.", getpid());
@@ -460,10 +455,8 @@ ssize_t shm_rdrbuff_write(struct shm_rdrbuff * rdrb,
         int                  sz = size + sizeof *sdb;
         uint8_t *            write_pos;
 
-        if (rdrb == NULL || data == NULL) {
-                LOG_DBGF("Bogus input, bugging out.");
-                return -1;
-        }
+        assert(rdrb);
+        assert(data);
 
 #ifndef SHM_RDRB_MULTI_BLOCK
         if (sz > SHM_RDRB_BLOCK_SIZE) {
@@ -534,11 +527,11 @@ ssize_t shm_rdrbuff_write(struct shm_rdrbuff * rdrb,
 }
 
 ssize_t shm_rdrbuff_write_b(struct shm_rdrbuff * rdrb,
-                           pid_t               dst_api,
-                           size_t              headspace,
-                           size_t              tailspace,
-                           uint8_t *           data,
-                           size_t              len)
+                           pid_t                 dst_api,
+                           size_t                headspace,
+                           size_t                tailspace,
+                           uint8_t *             data,
+                           size_t                len)
 {
         struct shm_du_buff * sdb;
         size_t               size = headspace + len + tailspace;
@@ -549,10 +542,8 @@ ssize_t shm_rdrbuff_write_b(struct shm_rdrbuff * rdrb,
         int                  sz = size + sizeof *sdb;
         uint8_t *            write_pos;
 
-        if (rdrb == NULL || data == NULL) {
-                LOG_DBGF("Bogus input, bugging out.");
-                return -1;
-        }
+        assert(rdrb);
+        assert(data);
 
 #ifndef SHM_RDRB_MULTI_BLOCK
         if (sz > SHM_RDRB_BLOCK_SIZE) {
@@ -631,6 +622,9 @@ int shm_rdrbuff_read(uint8_t **           dst,
         size_t len = 0;
         struct shm_du_buff * sdb;
 
+        assert(dst);
+        assert(rdrb);
+
         if (idx > SHM_BUFFER_SIZE)
                 return -1;
 #ifdef __APPLE__
@@ -659,6 +653,8 @@ struct shm_du_buff * shm_rdrbuff_get(struct shm_rdrbuff * rdrb, ssize_t idx)
 {
         struct shm_du_buff * sdb;
 
+        assert(rdrb);
+
         if (idx > SHM_BUFFER_SIZE)
                 return NULL;
 #ifdef __APPLE__
@@ -683,6 +679,8 @@ struct shm_du_buff * shm_rdrbuff_get(struct shm_rdrbuff * rdrb, ssize_t idx)
 
 int shm_rdrbuff_remove(struct shm_rdrbuff * rdrb, ssize_t idx)
 {
+        assert(rdrb);
+
         if (idx > SHM_BUFFER_SIZE)
                 return -1;
 #ifdef __APPLE__
@@ -717,21 +715,21 @@ int shm_rdrbuff_remove(struct shm_rdrbuff * rdrb, ssize_t idx)
 
 size_t shm_du_buff_get_idx(struct shm_du_buff * sdb)
 {
+        assert(sdb);
+
         return sdb->idx;
 }
 
 uint8_t * shm_du_buff_head(struct shm_du_buff * sdb)
 {
-        if (sdb == NULL)
-                return NULL;
+        assert(sdb);
 
         return (uint8_t *) (sdb + 1) + sdb->du_head;
 }
 
 uint8_t * shm_du_buff_tail(struct shm_du_buff * sdb)
 {
-        if (sdb == NULL)
-                return NULL;
+        assert(sdb);
 
         return (uint8_t *) (sdb + 1) + sdb->du_tail;
 }
@@ -741,8 +739,7 @@ uint8_t * shm_du_buff_head_alloc(struct shm_du_buff * sdb,
 {
         uint8_t * buf = NULL;
 
-        if (sdb  == NULL)
-                return NULL;
+        assert(sdb);
 
         if ((long) (sdb->du_head - size) < 0) {
                 LOG_ERR("Failed to allocate PCI headspace.");
@@ -761,8 +758,7 @@ uint8_t * shm_du_buff_tail_alloc(struct shm_du_buff * sdb,
 {
         uint8_t * buf = NULL;
 
-        if (sdb  == NULL)
-                return NULL;
+        assert(sdb);
 
         if (sdb->du_tail + size >= sdb->size) {
                 LOG_ERR("Failed to allocate PCI tailspace.");
@@ -779,8 +775,7 @@ uint8_t * shm_du_buff_tail_alloc(struct shm_du_buff * sdb,
 int shm_du_buff_head_release(struct shm_du_buff * sdb,
                              size_t               size)
 {
-        if (sdb  == NULL)
-                return -1;
+        assert(sdb);
 
         if (size > sdb->du_tail - sdb->du_head) {
                 LOG_DBGF("Tried to release beyond SDU boundary.");
@@ -795,8 +790,7 @@ int shm_du_buff_head_release(struct shm_du_buff * sdb,
 int shm_du_buff_tail_release(struct shm_du_buff * sdb,
                              size_t               size)
 {
-        if (sdb  == NULL)
-                return -1;
+        assert(sdb);
 
         if (size > sdb->du_tail - sdb->du_head) {
                 LOG_ERR("Tried to release beyond SDU boundary.");