lib: net_buf: move the network buffer implementation to lib

Move the net_buf implementation from the networking subsystem to a library
as they have no dependency on the networking subsystem.

Network buffers are used in subsystems outside of networking
(e.g. Bluetooth, USB).

Fixes: #36374

Signed-off-by: Henrik Brix Andersen <[email protected]>

Author: henrikbrixandersen

MAINTAINERS.yml

@@ -2803,7 +2803,6 @@ Networking:
     - samples/net/lwm2m_client/
     - samples/net/wifi/
     - samples/net/dhcpv4_client/
-    - subsys/net/buf*.c
     - subsys/net/l2/ethernet/gptp/
     - subsys/net/l2/ieee802154/
     - subsys/net/l2/wifi/
@@ -2846,7 +2845,7 @@ Networking:
     - jukkar
   files:
     - include/zephyr/net/buf.h
-    - subsys/net/buf*.c
+    - lib/net_buf/
     - tests/net/buf/
   labels:
     - "area: Networking Buffers"

lib/CMakeLists.txt

@@ -14,6 +14,7 @@ add_subdirectory_ifdef(CONFIG_CPP                  cpp)
 add_subdirectory(hash)
 add_subdirectory(heap)
 add_subdirectory(mem_blocks)
+add_subdirectory_ifdef(CONFIG_NET_BUF net_buf)
 add_subdirectory(os)
 add_subdirectory(utils)
 add_subdirectory_ifdef(CONFIG_SMF smf)

lib/Kconfig

@@ -15,6 +15,8 @@ source "lib/heap/Kconfig"
 
 source "lib/mem_blocks/Kconfig"
 
+source "lib/net_buf/Kconfig"
+
 source "lib/os/Kconfig"
 
 source "lib/posix/Kconfig"

lib/net_buf/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources_ifdef(
+  CONFIG_NET_BUF
+  buf.c
+  buf_simple.c
+  )

lib/net_buf/Kconfig

@@ -0,0 +1,62 @@
+# Network buffer configuration options
+
+# Copyright (c) 2015 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig NET_BUF
+	bool "Network buffer support"
+	help
+	  This option enables support for generic network protocol
+	  buffers.
+
+if NET_BUF
+
+config NET_BUF_LOG
+	bool "Network buffer logging"
+	select LOG
+	help
+	  Enable logs and checks for the generic network buffers.
+
+module = NET_BUF
+module-str = net_buf
+source "subsys/logging/Kconfig.template.log_config"
+
+if NET_BUF_LOG
+
+config NET_BUF_WARN_ALLOC_INTERVAL
+	int "Interval of Network buffer allocation warnings"
+	default 1
+	range 0 60
+	help
+	  Interval in seconds of Network buffer allocation warnings which are
+	  generated when a buffer cannot immediately be allocated with K_FOREVER
+	  which may lead to deadlocks. Setting it to 0 makes warnings to be
+	  printed only once per allocation.
+
+config NET_BUF_SIMPLE_LOG
+	bool "Network buffer memory debugging"
+	select LOG
+	help
+	  Enable extra debug logs and checks for the generic network buffers.
+
+endif # NET_BUF_LOG
+
+config NET_BUF_POOL_USAGE
+	bool "Network buffer pool usage tracking"
+	help
+	  Enable network buffer pool tracking. This means that:
+	  * amount of free buffers in the pool is remembered
+	  * total size of the pool is calculated
+	  * pool name is stored and can be shown in debugging prints
+
+config NET_BUF_ALIGNMENT
+	int "Network buffer alignment restriction"
+	default 0
+	help
+	  Alignment restriction for network buffers. This is useful for
+	  some hardware IP with DMA that requires the buffers to be aligned
+	  to a certain byte boundary, or dealing with cache line restrictions.
+	  Default value of 0 means the alignment will be the size of a void pointer,
+	  any other value will force the alignment of a net buffer in bytes.
+
+endif # NET_BUF

subsys/net/buf.c renamed to lib/net_buf/buf.c

@@ -47,7 +47,7 @@ add_subdirectory_ifdef(CONFIG_INPUT input)
 add_subdirectory_ifdef(CONFIG_JWT jwt)
 add_subdirectory_ifdef(CONFIG_LLEXT llext)
 add_subdirectory_ifdef(CONFIG_MODEM_MODULES modem)
-add_subdirectory_ifdef(CONFIG_NET_BUF net)
+add_subdirectory_ifdef(CONFIG_NETWORKING net)
 add_subdirectory_ifdef(CONFIG_PROFILING profiling)
 add_subdirectory_ifdef(CONFIG_RETENTION retention)
 add_subdirectory_ifdef(CONFIG_SENSING sensing)

subsys/net/buf_simple.c renamed to lib/net_buf/buf_simple.c

@@ -1,11 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 
 zephyr_library()
-zephyr_library_sources_ifdef(
-  CONFIG_NET_BUF
-  buf.c
-  buf_simple.c
-  )
 zephyr_library_sources_ifdef(CONFIG_NET_HOSTNAME_ENABLE hostname.c)
 
 if(CONFIG_NETWORKING)

subsys/CMakeLists.txt

@@ -5,64 +5,6 @@
 
 menu "Networking"
 
-config NET_BUF
-	bool "Network buffer support"
-	help
-	  This option enables support for generic network protocol
-	  buffers.
-
-if NET_BUF
-
-config NET_BUF_LOG
-	bool "Network buffer logging"
-	select LOG
-	help
-	  Enable logs and checks for the generic network buffers.
-
-module = NET_BUF
-module-str = net_buf
-source "subsys/logging/Kconfig.template.log_config"
-
-if NET_BUF_LOG
-
-config NET_BUF_WARN_ALLOC_INTERVAL
-	int "Interval of Network buffer allocation warnings"
-	default 1
-	range 0 60
-	help
-	  Interval in seconds of Network buffer allocation warnings which are
-	  generated when a buffer cannot immediately be allocated with K_FOREVER
-	  which may lead to deadlocks. Setting it to 0 makes warnings to be
-	  printed only once per allocation.
-
-config NET_BUF_SIMPLE_LOG
-	bool "Network buffer memory debugging"
-	select LOG
-	help
-	  Enable extra debug logs and checks for the generic network buffers.
-
-endif # NET_BUF_LOG
-
-config NET_BUF_POOL_USAGE
-	bool "Network buffer pool usage tracking"
-	help
-	  Enable network buffer pool tracking. This means that:
-	  * amount of free buffers in the pool is remembered
-	  * total size of the pool is calculated
-	  * pool name is stored and can be shown in debugging prints
-
-config NET_BUF_ALIGNMENT
-	int "Network buffer alignment restriction"
-	default 0
-	help
-	  Alignment restriction for network buffers. This is useful for
-	  some hardware IP with DMA that requires the buffers to be aligned
-	  to a certain byte boundary, or dealing with cache line restrictions.
-	  Default value of 0 means the alignment will be the size of a void pointer,
-	  any other value will force the alignment of a net buffer in bytes.
-
-endif # NET_BUF
-
 config NETWORKING
 	bool "Link layer and networking (including IP)"
 	select NET_BUF