net: Add net_buf_get_timeout() API

With this API it's possible for the caller to force specific behavior
when it comes to waiting (or not waiting) on the FIFO.

Change-Id: Ib66e2f767c26c82abf1ba3b80bd15aec2383542e
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/buf.h

@@ -127,10 +127,28 @@ struct net_buf {
  *
  *  @warning If there are no available buffers and the function is
  *  called from a task or fiber the call will block until a buffer
- *  becomes available in the pool.
+ *  becomes available in the pool. If you want to make sure no blocking
+ *  happens use net_buf_get_timeout() instead with TICKS_NONE.
  */
 struct net_buf *net_buf_get(struct nano_fifo *fifo, size_t reserve_head);
 
+/** @brief Get a new buffer from the pool.
+ *
+ *  Get buffer from the available buffers pool with specified type and
+ *  reserved headroom.
+ *
+ *  @param fifo Which FIFO to take the buffer from.
+ *  @param reserve_head How much headroom to reserve.
+ *  @param timeout Affects the action taken should the pool (FIFO) be empty.
+ *         If TICKS_NONE, then return immediately. If TICKS_UNLIMITED, then
+ *         wait as long as necessary. Otherwise, wait up to the specified
+ *         number of ticks before timing out.
+ *
+ *  @return New buffer or NULL if out of buffers.
+ */
+struct net_buf *net_buf_get_timeout(struct nano_fifo *fifo,
+				    size_t reserve_head, int32_t timeout);
+
 /** @brief Decrements the reference count of a buffer.
  *
  *  Decrements the reference count of a buffer and puts it back into the

net/buf.c

@@ -43,21 +43,18 @@
 #define NET_BUF_ASSERT(cond)
 #endif /* CONFIG_NET_BUF_DEBUG */
 
-struct net_buf *net_buf_get(struct nano_fifo *fifo, size_t reserve_head)
+struct net_buf *net_buf_get_timeout(struct nano_fifo *fifo,
+				    size_t reserve_head, int32_t timeout)
 {
 	struct net_buf *buf;
 
-	NET_BUF_DBG("fifo %p reserve %u\n", fifo, reserve_head);
+	NET_BUF_DBG("fifo %p reserve %u timeout %d\n", fifo, reserve_head,
+		    timeout);
 
-	buf = nano_fifo_get(fifo, TICKS_NONE);
+	buf = nano_fifo_get(fifo, timeout);
 	if (!buf) {
-		if (sys_execution_context_type_get() == NANO_CTX_ISR) {
+		NET_BUF_ERR("Failed to get free buffer\n");
-			NET_BUF_ERR("Failed to get free buffer\n");
+		return NULL;
-			return NULL;
-		}
-
-		NET_BUF_WARN("Low on buffers. Waiting (fifo %p)\n", fifo);
-		buf = nano_fifo_get(fifo, TICKS_UNLIMITED);
 	}
 
 	buf->ref  = 1;
@@ -69,6 +66,22 @@ struct net_buf *net_buf_get(struct nano_fifo *fifo, size_t reserve_head)
 	return buf;
 }
 
+struct net_buf *net_buf_get(struct nano_fifo *fifo, size_t reserve_head)
+{
+	struct net_buf *buf;
+
+	NET_BUF_DBG("fifo %p reserve %u\n", fifo, reserve_head);
+
+	buf = net_buf_get_timeout(fifo, reserve_head, TICKS_NONE);
+	if (buf || sys_execution_context_type_get() == NANO_CTX_ISR) {
+		return buf;
+	}
+
+	NET_BUF_WARN("Low on buffers. Waiting (fifo %p)\n", fifo);
+
+	return net_buf_get_timeout(fifo, reserve_head, TICKS_UNLIMITED);
+}
+
 void net_buf_unref(struct net_buf *buf)
 {
 	NET_BUF_DBG("buf %p ref %u fifo %p\n", buf, buf->ref, buf->free);