dynamic_debug: add an option to enable dynamic debug for modules only

Instead of enabling dynamic debug globally with CONFIG_DYNAMIC_DEBUG,
CONFIG_DYNAMIC_DEBUG_CORE will only enable core function of dynamic
debug.  With the DYNAMIC_DEBUG_MODULE defined for any modules, dynamic
debug will be tied to them.

This is useful for people who only want to enable dynamic debug for
kernel modules without worrying about kernel image size and memory
consumption is increasing too much.

[orson.zhai@unisoc.com: v2]
Link: http://lkml.kernel.org/r/1587408228-10861-1-git-send-email-orson.unisoc@gmail.com
Signed-off-by: Orson Zhai <orson.zhai@unisoc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/1586521984-5890-1-git-send-email-orson.unisoc@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 0dc2eb8e44e5fa56ad19cb1191f182090ee614f8..1012bd9305e905f9b75cc0539fae1f9fe0531f60 100644 (file)
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -13,6 +13,11 @@ kernel code to obtain additional kernel information.  Currently, if
 ``print_hex_dump_debug()``/``print_hex_dump_bytes()`` calls can be dynamically
 enabled per-callsite.
 
+If you do not want to enable dynamic debug globally (i.e. in some embedded
+system), you may set ``CONFIG_DYNAMIC_DEBUG_CORE`` as basic support of dynamic
+debug and add ``ccflags := -DDYNAMIC_DEBUG_MODULE`` into the Makefile of any
+modules which you'd like to dynamically debug later.
+
 If ``CONFIG_DYNAMIC_DEBUG`` is not set, ``print_hex_dump_debug()`` is just
 shortcut for ``print_hex_dump(KERN_DEBUG)``.
 

diff --git a/include/linux/dev_printk.h b/include/linux/dev_printk.h
index 5aad06b4ca7bb1341d8991a212f1a4b8d7ec0b1b..3028b644b4fbde5dbfa3bdf298b042b669830a02 100644 (file)
--- a/include/linux/dev_printk.h
+++ b/include/linux/dev_printk.h
@@ -109,7 +109,8 @@ void _dev_info(const struct device *dev, const char *fmt, ...)
 #define dev_info(dev, fmt, ...)                                                \
        _dev_info(dev, dev_fmt(fmt), ##__VA_ARGS__)
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define dev_dbg(dev, fmt, ...)                                         \
        dynamic_dev_dbg(dev, dev_fmt(fmt), ##__VA_ARGS__)
 #elif defined(DEBUG)
@@ -181,7 +182,8 @@ do {                                                                        \
        dev_level_ratelimited(dev_notice, dev, fmt, ##__VA_ARGS__)
 #define dev_info_ratelimited(dev, fmt, ...)                            \
        dev_level_ratelimited(dev_info, dev, fmt, ##__VA_ARGS__)
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 /* descriptor check is first to prevent flooding with "callbacks suppressed" */
 #define dev_dbg_ratelimited(dev, fmt, ...)                             \
 do {                                                                   \

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 4cf02ecd67de7f61c84ec7c8db22d48cd900fb85..abcd5fde30eb736e428fba8b27c8a096e32e8793 100644 (file)
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -48,7 +48,7 @@ struct _ddebug {
 
 
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG_CORE)
 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
                                const char *modname);
 extern int ddebug_remove_module(const char *mod_name);

diff --git a/include/linux/net.h b/include/linux/net.h
index e10f378194a59d22c6305f1737757852587b17d7..016a9c5faa3479b968443b1db07c1150e7e3a0f7 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -264,7 +264,8 @@ do {                                                                \
        net_ratelimited_function(pr_warn, fmt, ##__VA_ARGS__)
 #define net_info_ratelimited(fmt, ...)                         \
        net_ratelimited_function(pr_info, fmt, ##__VA_ARGS__)
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define net_dbg_ratelimited(fmt, ...)                                  \
 do {                                                                   \
        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);                 \

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1a96e9c4ec36fce56d2b167298411277710eb84b..5b364a2e0006250e440a988b2a72da9a046bc70f 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4942,7 +4942,8 @@ do {                                                              \
 #define MODULE_ALIAS_NETDEV(device) \
        MODULE_ALIAS("netdev-" device)
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define netdev_dbg(__dev, format, args...)                     \
 do {                                                           \
        dynamic_netdev_dbg(__dev, format, ##args);              \
@@ -5012,7 +5013,8 @@ do {                                                              \
 #define netif_info(priv, type, dev, fmt, args...)              \
        netif_level(info, priv, type, dev, fmt, ##args)
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define netif_dbg(priv, type, netdev, format, args...)         \
 do {                                                           \
        if (netif_msg_##type(priv))                             \

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 3cc2f178bf06f03536df767e498a1e20162b2aec..fc8f03c545430292daa322b8dd941d88f951dc2f 100644 (file)
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -399,7 +399,8 @@ extern int kptr_restrict;
 
 
 /* If you are writing a driver, please use dev_dbg instead */
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #include <linux/dynamic_debug.h>
 
 /**
@@ -535,7 +536,8 @@ extern int kptr_restrict;
 #endif
 
 /* If you are writing a driver, please use dev_dbg instead */
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 /* descriptor check is first to prevent flooding with "callbacks suppressed" */
 #define pr_debug_ratelimited(fmt, ...)                                 \
 do {                                                                   \
@@ -582,7 +584,8 @@ static inline void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
 
 #endif
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define print_hex_dump_debug(prefix_str, prefix_type, rowsize, \
                             groupsize, buf, len, ascii)        \
        dynamic_hex_dump(prefix_str, prefix_type, rowsize,      \

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 033e7044f29c35b9fdee21c75614807d354e4bb4..ef2f3986c4933434d27b482e20747c2e8c491456 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -100,7 +100,8 @@ void ibdev_notice(const struct ib_device *ibdev, const char *format, ...);
 __printf(2, 3) __cold
 void ibdev_info(const struct ib_device *ibdev, const char *format, ...);
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 #define ibdev_dbg(__dev, format, args...)                       \
        dynamic_ibdev_dbg(__dev, format, ##args)
 #else
@@ -133,7 +134,8 @@ do {                                                                    \
 #define ibdev_info_ratelimited(ibdev, fmt, ...) \
        ibdev_level_ratelimited(ibdev_info, ibdev, fmt, ##__VA_ARGS__)
 
-#if defined(CONFIG_DYNAMIC_DEBUG)
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 /* descriptor check is first to prevent flooding with "callbacks suppressed" */
 #define ibdev_dbg_ratelimited(ibdev, fmt, ...)                          \
 do {                                                                    \

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9bd4eb7f5ec1952c97a6dddbb42eab37bbe9cdc7..333e878d8af95b2a27e034df0f5e033b7c72ca25 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -99,6 +99,7 @@ config DYNAMIC_DEBUG
        default n
        depends on PRINTK
        depends on (DEBUG_FS || PROC_FS)
+       select DYNAMIC_DEBUG_CORE
        help
 
          Compiles debug level messages into the kernel, which would not
@@ -165,6 +166,17 @@ config DYNAMIC_DEBUG
          See Documentation/admin-guide/dynamic-debug-howto.rst for additional
          information.
 
+config DYNAMIC_DEBUG_CORE
+       bool "Enable core function of dynamic debug support"
+       depends on PRINTK
+       depends on (DEBUG_FS || PROC_FS)
+       help
+         Enable core functional support of dynamic debug. It is useful
+         when you want to tie dynamic debug to your kernel modules with
+         DYNAMIC_DEBUG_MODULE defined for each of them, especially for
+         the case of embedded system where the kernel image size is
+         sensitive for people.
+
 config SYMBOLIC_ERRNAME
        bool "Support symbolic error names in printf"
        default y if PRINTK

diff --git a/lib/Makefile b/lib/Makefile
index 32f19b4d1d2a6209a55d19d0159ef19086b83a5b..315516fa4ef45b9a231fdb0a274b35482d25d346 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -190,7 +190,7 @@ lib-$(CONFIG_GENERIC_BUG) += bug.o
 
 obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
 
-obj-$(CONFIG_DYNAMIC_DEBUG) += dynamic_debug.o
+obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o
 obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
 
 obj-$(CONFIG_NLATTR) += nlattr.o

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8f199f403ab50656c4d91344932204bee6ac9d17..321437bbf87dd304a82d3452766b2102e60e7383 100644 (file)
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1032,8 +1032,13 @@ static int __init dynamic_debug_init(void)
        int verbose_bytes = 0;
 
        if (&__start___verbose == &__stop___verbose) {
-               pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
-               return 1;
+               if (IS_ENABLED(CONFIG_DYNAMIC_DEBUG)) {
+                       pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
+                       return 1;
+               }
+               pr_info("Ignore empty _ddebug table in a CONFIG_DYNAMIC_DEBUG_CORE build\n");
+               ddebug_init_success = 1;
+               return 0;
        }
        iter = __start___verbose;
        modname = iter->modname;