Pull net buf revert

include/zephyr/net_buf.h

@@ -1325,19 +1325,14 @@ int net_buf_id(const struct net_buf *buf);
 /**
  * @brief Allocate a new fixed buffer from a pool.
  *
- * @note Some types of data allocators do not support
- *       blocking (such as the HEAP type). In this case it's still possible
- *       for net_buf_alloc() to fail (return NULL) even if it was given
- *       K_FOREVER.
- *
- * @note The timeout value will be overridden to K_NO_WAIT if called from the
- *       system workqueue.
- *
  * @param pool Which pool to allocate the buffer from.
  * @param timeout Affects the action taken should the pool be empty.
  *        If K_NO_WAIT, then return immediately. If K_FOREVER, then
  *        wait as long as necessary. Otherwise, wait until the specified
- *        timeout.
+ *        timeout. Note that some types of data allocators do not support
+ *        blocking (such as the HEAP type). In this case it's still possible
+ *        for net_buf_alloc() to fail (return NULL) even if it was given
+ *        K_FOREVER.
  *
  * @return New buffer or NULL if out of buffers.
  */
@@ -1365,20 +1360,15 @@ static inline struct net_buf * __must_check net_buf_alloc(struct net_buf_pool *p
 /**
  * @brief Allocate a new variable length buffer from a pool.
  *
- * @note Some types of data allocators do not support
- *       blocking (such as the HEAP type). In this case it's still possible
- *       for net_buf_alloc() to fail (return NULL) even if it was given
- *       K_FOREVER.
- *
- * @note The timeout value will be overridden to K_NO_WAIT if called from the
- *       system workqueue.
- *
  * @param pool Which pool to allocate the buffer from.
  * @param size Amount of data the buffer must be able to fit.
  * @param timeout Affects the action taken should the pool be empty.
  *        If K_NO_WAIT, then return immediately. If K_FOREVER, then
  *        wait as long as necessary. Otherwise, wait until the specified
- *        timeout.
+ *        timeout. Note that some types of data allocators do not support
+ *        blocking (such as the HEAP type). In this case it's still possible
+ *        for net_buf_alloc() to fail (return NULL) even if it was given
+ *        K_FOREVER.
  *
  * @return New buffer or NULL if out of buffers.
  */
@@ -1402,21 +1392,16 @@ struct net_buf * __must_check net_buf_alloc_len(struct net_buf_pool *pool,
  * Allocate a new buffer from a pool, where the data pointer comes from the
  * user and not from the pool.
  *
- * @note Some types of data allocators do not support
- *       blocking (such as the HEAP type). In this case it's still possible
- *       for net_buf_alloc() to fail (return NULL) even if it was given
- *       K_FOREVER.
- *
- * @note The timeout value will be overridden to K_NO_WAIT if called from the
- *       system workqueue.
- *
  * @param pool Which pool to allocate the buffer from.
  * @param data External data pointer
  * @param size Amount of data the pointed data buffer if able to fit.
  * @param timeout Affects the action taken should the pool be empty.
  *        If K_NO_WAIT, then return immediately. If K_FOREVER, then
  *        wait as long as necessary. Otherwise, wait until the specified
- *        timeout.
+ *        timeout. Note that some types of data allocators do not support
+ *        blocking (such as the HEAP type). In this case it's still possible
+ *        for net_buf_alloc() to fail (return NULL) even if it was given
+ *        K_FOREVER.
  *
  * @return New buffer or NULL if out of buffers.
  */

lib/net_buf/buf.c

@@ -271,12 +271,6 @@ struct net_buf *net_buf_alloc_len(struct net_buf_pool *pool, size_t size,
 
 	k_spin_unlock(&pool->lock, key);
 
-	if (!K_TIMEOUT_EQ(timeout, K_NO_WAIT) &&
-	    k_current_get() == k_work_queue_thread_get(&k_sys_work_q)) {
-		LOG_DBG("Timeout discarded. No blocking in syswq");
-		timeout = K_NO_WAIT;
-	}
-
 #if defined(CONFIG_NET_BUF_LOG) && (CONFIG_NET_BUF_LOG_LEVEL >= LOG_LEVEL_WRN)
 	if (K_TIMEOUT_EQ(timeout, K_FOREVER)) {
 		uint32_t ref = k_uptime_get_32();

subsys/bluetooth/mesh/Kconfig

@@ -130,10 +130,12 @@ config BT_MESH_WORKQ_SYS
 	  refer to BT_MESH_ADV_STACK_SIZE for the recommended minimum.
 
 	  When this option is enabled and the mesh tries to send a message,
-	  and the host ran out the HCI command buffers controlled by
-	  CONFIG_BT_BUF_CMD_TX_COUNT, the host returns -ENOBUFS immediately
-	  and the mesh drops the message transmission. To mitigate this
-	  issue, make sure to have sufficient number of HCI command buffers.
+	  and the host ran out of the HCI command buffers controlled by
+	  CONFIG_BT_BUF_CMD_TX_COUNT, the system work queue will be blocked
+	  until an HCI command buffer has been freed. This may cause a deadlock
+	  where the host cannot use the system workqueue to free the buffer
+	  that the mesh is waiting for. To mitigate this issue, make sure to
+	  have a sufficient number of HCI command buffers.
 	  When this option is enabled, the latency of sending mesh messages
 	  will be affected by other users on the system work queue, resulting in
 	  reduced reliability for sending mesh messages.