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From:   Alain Michaud <alainm@chromium.org>
To:     linux-bluetooth@vger.kernel.org
Cc:     Alain Michaud <alainm@chromium.org>,
        Archie Pusaka <apusaka@chromium.org>
Subject: [PATCH v2] Bluetooth: create CONFIG_BT_DEBUG_FEATURE_FUNC_NAME
Date:   Tue,  7 Jul 2020 14:16:28 +0000
Message-Id: <20200707141628.368748-1-alainm@chromium.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Creates a CONFIG_BT_DEBUG_FEATURE_FUNC_NAME option to include function names in
debug statements.

Unlike other platforms __func__ isn't a string literal so it cannot be
automatically concatenated by the pre-processor.  As a result, the
function name is passed as a parameter to the tracing function.  Since
pr_debug is a function like macro, the normal expansion of BT_PREFIX_PARAM
does not work as it gets processed within the first parameter as well,
for this reason, BT_DBG is split into two versions.

This patch was built tested with all 4 possible combinations of
CONFIG_BT_DEBUG_FUNC_NAME and CONFIG_BT_FEATURE_DEBUG configurations.

Signed-off-by: Alain Michaud <alainm@chromium.org>
Reviewed-by: Archie Pusaka <apusaka@chromium.org>
---

Changes in v2:
 - Making CONFIG_BT_DEBUG_FEATURE_FUNC_NAME dependent on
 CONFIG_BT_DEBUG_FEATURE

 include/net/bluetooth/bluetooth.h | 32 +++++++++++++++++++++++--------
 net/bluetooth/Kconfig             | 11 +++++++++++
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index 7ee8041af803..8506dd268d4b 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -162,22 +162,37 @@ void bt_dbg_set(bool enable);
 bool bt_dbg_get(void);
 __printf(1, 2)
 void bt_dbg(const char *fmt, ...);
+#define BT_DBG_INT	bt_dbg
+#else
+#define BT_DBG_INT	pr_debug
 #endif
 __printf(1, 2)
 void bt_warn_ratelimited(const char *fmt, ...);
 __printf(1, 2)
 void bt_err_ratelimited(const char *fmt, ...);
 
-#define BT_INFO(fmt, ...)	bt_info(fmt "\n", ##__VA_ARGS__)
-#define BT_WARN(fmt, ...)	bt_warn(fmt "\n", ##__VA_ARGS__)
-#define BT_ERR(fmt, ...)	bt_err(fmt "\n", ##__VA_ARGS__)
-
-#if IS_ENABLED(CONFIG_BT_FEATURE_DEBUG)
-#define BT_DBG(fmt, ...)	bt_dbg(fmt "\n", ##__VA_ARGS__)
+#if IS_ENABLED(BT_FEATURE_DEBUG_FUNC_NAMES)
+#define BT_PREFIX "%s() "
+#define BT_PREFIX_PARAM ,__func__
+#define BT_DBG(fmt, ...)	\
+	BT_DBG_INT(BT_PREFIX fmt "\n", __func__, ##__VA_ARGS__)
 #else
-#define BT_DBG(fmt, ...)	pr_debug(fmt "\n", ##__VA_ARGS__)
+#define BT_PREFIX
+#define BT_PREFIX_PARAM
+#define BT_DBG(fmt, ...)	\
+	BT_DBG_INT(fmt "\n", ##__VA_ARGS__)
 #endif
 
+#define BT_INFO(fmt, ...)	\
+	bt_info(BT_PREFIX fmt "\n" BT_PREFIX_PARAM, ##__VA_ARGS__)
+#define BT_WARN(fmt, ...)	\
+	bt_warn(BT_PREFIX fmt "\n" BT_PREFIX_PARAM, ##__VA_ARGS__)
+#define BT_ERR(fmt, ...)	\
+	bt_err(BT_PREFIX fmt "\n" BT_PREFIX_PARAM, ##__VA_ARGS__)
+
+#define BT_ERR_RATELIMITED(fmt, ...) \
+	bt_err_ratelimited(BT_PREFIX fmt "\n" BT_PREFIX_PARAM, ##__VA_ARGS__)
+
 #define bt_dev_info(hdev, fmt, ...)				\
 	BT_INFO("%s: " fmt, (hdev)->name, ##__VA_ARGS__)
 #define bt_dev_warn(hdev, fmt, ...)				\
@@ -188,7 +203,8 @@ void bt_err_ratelimited(const char *fmt, ...);
 	BT_DBG("%s: " fmt, (hdev)->name, ##__VA_ARGS__)
 
 #define bt_dev_warn_ratelimited(hdev, fmt, ...)			\
-	bt_warn_ratelimited("%s: " fmt, (hdev)->name, ##__VA_ARGS__)
+	bt_warn_ratelimited("%s: " BT_PREFIX fmt, (hdev)->name	\
+			    BT_PREFIX_PARAM, ##__VA_ARGS__)
 #define bt_dev_err_ratelimited(hdev, fmt, ...)			\
 	bt_err_ratelimited("%s: " fmt, (hdev)->name, ##__VA_ARGS__)
 
diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
index 1d6d243cdde9..ccbf762053f1 100644
--- a/net/bluetooth/Kconfig
+++ b/net/bluetooth/Kconfig
@@ -142,4 +142,15 @@ config BT_FEATURE_DEBUG
 	  This provides an option to enable/disable debugging statements
 	  at runtime via the experimental features interface.
 
+config BT_FEATURE_DEBUG_FUNC_NAMES
+	bool "Include function names in debugging statements"
+	depends on BT_FEATURE_DEBUG
+	default n
+	help
+	  Provides an option to include function names in debugging
+	  statements.
+
+	  When enabled, trace statements will include the function name as a
+	  prefix which may help identify the source code references.
+
 source "drivers/bluetooth/Kconfig"
-- 
2.27.0.212.ge8ba1cc988-goog