Merge pull request #1808 from qlyoung/debug-mt-safe

MT-safe debug facilities

5 files changed, 290 insertions, 0 deletions

diff --git a/lib/debug.c b/lib/debug.c
new file mode 100644
index 000000000..0bacf9789
--- /dev/null
+++ b/lib/debug.c
@@ -0,0 +1,46 @@
+/*
+ * Debugging utilities.
+ * Copyright (C) 2018  Cumulus Networks, Inc.
+ * Quentin Young
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <zebra.h>
+#include "debug.h"
+#include "command.h"
+
+static const struct debug_callbacks *callbacks;
+
+/* All code in this section should be reentrant and MT-safe */
+
+DEFUN_NOSH(debug_all, debug_all_cmd, "[no] debug all",
+	   NO_STR DEBUG_STR "Toggle all debugging output\n")
+{
+	bool set = strmatch(argv[0]->text, "no");
+	uint32_t mode = DEBUG_NODE2MODE(vty->node);
+
+	if (callbacks->debug_set_all)
+		callbacks->debug_set_all(mode, set);
+	return CMD_SUCCESS;
+}
+
+/* ------------------------------------------------------------------------- */
+
+void debug_init(const struct debug_callbacks *cb)
+{
+	callbacks = cb;
+	install_element(ENABLE_NODE, &debug_all_cmd);
+	install_element(CONFIG_NODE, &debug_all_cmd);
+}
diff --git a/lib/debug.h b/lib/debug.h
new file mode 100644
index 000000000..3e6772aac
--- /dev/null
+++ b/lib/debug.h
@@ -0,0 +1,216 @@
+/*
+ * Debugging utilities.
+ * Copyright (C) 2018  Cumulus Networks, Inc.
+ * Quentin Young
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#ifndef _FRRDEBUG_H
+#define _FRRDEBUG_H
+
+#include <zebra.h>
+#include "command.h"
+#include "frratomic.h"
+
+/*
+ * Debugging modes.
+ *
+ * FRR's convention is that a debug statement issued under the vty CONFIG_NODE
+ * persists to the config file, whereas the same debug statement issued from
+ * the ENABLE_NODE only persists for the current session. These are mapped to
+ * DEBUG_MODE_CONF and DEBUG_MODE_TERM respectively.
+ *
+ * They are not mutually exclusive and are placed in the MSB of the flags
+ * field in a debugging record.
+ */
+#define DEBUG_MODE_TERM 0x01000000
+#define DEBUG_MODE_CONF 0x02000000
+#define DEBUG_MODE_ALL (DEBUG_MODE_TERM | DEBUG_MODE_CONF)
+#define DEBUG_MODE_NONE 0x00000000
+#define DEBUG_OPT_ALL 0x00FFFFFF
+#define DEBUG_OPT_NONE 0x00000000
+
+
+/*
+ * Debugging record.
+ *
+ * All operations on this record exposed in this header are MT-safe.
+ *
+ * flags
+ *    A bitfield with the following format (bytes high to low)
+ *    - [0] Debugging mode field (MSB)  | Mode
+ *    - [1] Arbitrary flag field        | Option
+ *    - [2] Arbitrary flag field        | Option
+ *    - [3] Arbitrary flag field (LSB)  | Option
+ *
+ *              ALL THESE BYTES ARE YOURS - EXCEPT MODE.
+ *                      ATTEMPT NO BIT OPS THERE.
+ *
+ *    The MSB of this field determines the debug mode, Use the DEBUG_MODE*
+ *    macros to manipulate this byte.
+ *
+ *    The low 3 bytes of this field may be used to store arbitrary information.
+ *    Usually they are used to store flags that tune how detailed the logging
+ *    for a particular debug record is. Use the DEBUG_OPT* macros to manipulate
+ *    those bytes.
+ *
+ *    All operations performed on this field should be done using the macros
+ *    later in this header file. They are guaranteed to be atomic operations
+ *    with respect to this field. Using anything except the macros to
+ *    manipulate the flags field in a multithreaded environment results in
+ *    undefined behavior.
+ *
+ * desc
+ *    Human-readable description of this debugging record.
+ */
+struct debug {
+	_Atomic uint32_t flags;
+	const char *desc;
+};
+
+/*
+ * Callback set for debugging code.
+ *
+ * debug_set_all
+ *    Function pointer to call when the user requests that all debugs have a
+ *    mode set.
+ */
+struct debug_callbacks {
+	/*
+	 * flags
+	 *    flags to set on debug flag fields
+	 *
+	 * set
+	 *    true: set flags
+	 *    false: unset flags
+	 */
+	void (*debug_set_all)(uint32_t flags, bool set);
+};
+
+/*
+ * Check if a mode is set for a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_MODE_CHECK(name, type)                                           \
+	CHECK_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_MODE_ALL)
+
+/*
+ * Check if an option bit is set for a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_OPT_CHECK(name, type)                                            \
+	CHECK_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_OPT_ALL)
+
+/*
+ * Check if bits are set for a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_FLAGS_CHECK(name, type) CHECK_FLAG_ATOMIC(&(name)->flags, (type))
+
+/*
+ * Check if any mode is on for a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG(name) DEBUG_MODE_CHECK((name), DEBUG_MODE_ALL)
+
+/*
+ * Set modes on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_MODE_SET(name, type)                                             \
+	SET_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_MODE_ALL)
+
+/*
+ * Unset modes on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_MODE_UNSET(name, type)                                           \
+	UNSET_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_MODE_ALL)
+
+/*
+ * Set options on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_OPT_SET(name, type)                                              \
+	SET_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_OPT_ALL)
+
+/*
+ * Unset options on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_OPT_UNSET(name, type)                                            \
+	UNSET_FLAG_ATOMIC(&(name)->flags, (type)&DEBUG_OPT_ALL)
+
+/*
+ * Set bits on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_FLAGS_SET(name, type) SET_FLAG_ATOMIC(&(name)->flags, (type))
+
+/*
+ * Unset bits on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_FLAGS_UNSET(name, type) UNSET_FLAG_ATOMIC(&(name)->flags, (type))
+
+/*
+ * Unset all modes and options on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_CLEAR(name) RESET_FLAG_ATOMIC(&(name)->flags)
+
+/*
+ * Set all modes and options on a debug.
+ *
+ * MT-Safe
+ */
+#define DEBUG_ON(name)                                                         \
+	SET_FLAG_ATOMIC(&(name)->flags, DEBUG_MODE_ALL | DEBUG_OPT_ALL)
+
+/*
+ * Map a vty node to the correct debugging mode flags. FRR behaves such that a
+ * debug statement issued under the config node persists to the config file,
+ * whereas the same debug statement issued from the enable node only persists
+ * for the current session.
+ *
+ * MT-Safe
+ */
+#define DEBUG_NODE2MODE(vtynode)                                               \
+	(((vtynode) == CONFIG_NODE) ? DEBUG_MODE_ALL : DEBUG_MODE_TERM)
+
+
+/*
+ * Optional initializer for debugging. Highly recommended.
+ *
+ * This function installs common debugging commands and allows the caller to
+ * specify callbacks to take when these commands are issued, allowing the
+ * caller to respond to events such as a request to turn off all debugs.
+ *
+ * MT-Safe
+ */
+void debug_init(const struct debug_callbacks *cb);
+
+#endif /* _FRRDEBUG_H */
diff --git a/lib/frratomic.h b/lib/frratomic.h
index 4ae84c401..689b25255 100644
--- a/lib/frratomic.h
+++ b/lib/frratomic.h
@@ -46,6 +46,8 @@
 #define atomic_exchange_explicit __atomic_exchange_n
 #define atomic_fetch_add_explicit __atomic_fetch_add
 #define atomic_fetch_sub_explicit __atomic_fetch_sub
+#define atomic_fetch_and_explicit __atomic_fetch_and
+#define atomic_fetch_or_explicit __atomic_fetch_or
 
 #define atomic_compare_exchange_weak_explicit(atom, expect, desire, mem1,      \
 					      mem2)                            \
@@ -135,6 +137,20 @@
 		*_expect = rval;                                               \
 		ret;                                                           \
 	})
+#define atomic_fetch_and_explicit(ptr, val, mem)                               \
+	({                                                                     \
+		__sync_synchronize();                                          \
+		typeof(*ptr) rval = __sync_fetch_and_and(ptr, val);            \
+		__sync_synchronize();                                          \
+		rval;                                                          \
+	})
+#define atomic_fetch_or_explicit(ptr, val, mem)                                \
+	({                                                                     \
+		__sync_synchronize();                                          \
+		typeof(*ptr) rval = __sync_fetch_and_or(ptr, val);             \
+		__sync_synchronize();                                          \
+		rval;                                                          \
+	})
 
 #else /* !HAVE___ATOMIC && !HAVE_STDATOMIC_H */
 #error no atomic functions...
diff --git a/lib/subdir.am b/lib/subdir.am
index e292d7a34..c8da5a2a8 100644
--- a/lib/subdir.am
+++ b/lib/subdir.am
@@ -15,6 +15,7 @@ lib_libfrr_la_SOURCES = \
 	lib/command_match.c \
 	lib/command_parse.y \
 	lib/csv.c \
+	lib/debug.c \
 	lib/distribute.c \
 	lib/event_counter.c \
 	lib/ferr.c \
@@ -91,6 +92,7 @@ pkginclude_HEADERS += \
 	lib/command_match.h \
 	lib/compiler.h \
 	lib/csv.h \
+	lib/debug.h \
 	lib/distribute.h \
 	lib/event_counter.h \
 	lib/ferr.h \
diff --git a/lib/zebra.h b/lib/zebra.h
index df367bd27..262ad2e43 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -481,6 +481,16 @@ typedef enum {
 #define UNSET_FLAG(V,F)      (V) &= ~(F)
 #define RESET_FLAG(V)        (V) = 0
 
+/* Atomic flag manipulation macros. */
+#define CHECK_FLAG_ATOMIC(PV, F)                                               \
+	((atomic_load_explicit(PV, memory_order_seq_cst)) & (F))
+#define SET_FLAG_ATOMIC(PV, F)                                                 \
+	((atomic_fetch_or_explicit(PV, (F), memory_order_seq_cst)))
+#define UNSET_FLAG_ATOMIC(PV, F)                                               \
+	((atomic_fetch_and_explicit(PV, ~(F), memory_order_seq_cst)))
+#define RESET_FLAG_ATOMIC(PV)                                                  \
+	((atomic_store_explicit(PV, 0, memory_order_seq_cst)))
+
 /* Zebra types. Used in Zserv message header. */
 typedef u_int16_t zebra_size_t;
 typedef u_int16_t zebra_command_t;