logging: merge branch 'th/logging-keep-bgo756175'

https://bugzilla.gnome.org/show_bug.cgi?id=756175

5 files changed, 225 insertions, 154 deletions

diff --git a/introspection/nm-manager.xml b/introspection/nm-manager.xml
index 88f477d62f..36cbee3011 100644
--- a/introspection/nm-manager.xml
+++ b/introspection/nm-manager.xml
@@ -184,7 +184,13 @@
       </tp:docstring>
       <arg name="level" type="s" direction="in">
         <tp:docstring>
-          One of [ERR, WARN, INFO, DEBUG, TRACE].
+          One of [ERR, WARN, INFO, DEBUG, TRACE, OFF, KEEP].
+          This level is applied to the domains as specified in the domains
+          argument. Except for the special level "KEEP", all unmentioned
+          domains are disabled entirely. "KEEP" is special and allows
+          not to change the current setting except for the specified
+          domains. E.g. level=KEEP and domains=PLATFORM:DEBUG will only
+          touch the platform domain.
         </tp:docstring>
       </arg>
       <arg name="domains" type="s" direction="in">
diff --git a/src/nm-logging.c b/src/nm-logging.c
index 30c754d163..60ccb5cb2f 100644
--- a/src/nm-logging.c
+++ b/src/nm-logging.c
@@ -40,6 +40,7 @@
 #include "nm-default.h"
 #include "nm-errors.h"
 #include "NetworkManagerUtils.h"
+#include "nm-linux-platform.h"
 
 static void
 nm_log_handler (const gchar *log_domain,
@@ -47,18 +48,6 @@ nm_log_handler (const gchar *log_domain,
                 const gchar *message,
                 gpointer ignored);
 
-static NMLogLevel log_level = LOGL_INFO;
-static char *log_domains;
-static NMLogDomain logging[_LOGL_N_REAL];
-static gboolean logging_set_up;
-enum {
-	LOG_BACKEND_GLIB,
-	LOG_BACKEND_SYSLOG,
-	LOG_BACKEND_JOURNAL,
-	LOG_BACKEND_JOURNAL_SYSLOG_STYLE,
-} log_backend = LOG_BACKEND_GLIB;
-static char *logging_domains_to_string;
-
 typedef struct {
 	NMLogDomain num;
 	const char *name;
@@ -72,52 +61,74 @@ typedef struct {
 	gboolean full_details;
 } LogLevelDesc;
 
-static const LogLevelDesc level_desc[_LOGL_N] = {
-	[LOGL_TRACE] = { "TRACE", "<trace>", LOG_DEBUG,   G_LOG_LEVEL_DEBUG,   TRUE  },
-	[LOGL_DEBUG] = { "DEBUG", "<debug>", LOG_INFO,    G_LOG_LEVEL_DEBUG,   TRUE  },
-	[LOGL_INFO]  = { "INFO",  "<info>",  LOG_INFO,    G_LOG_LEVEL_MESSAGE, FALSE },
-	[LOGL_WARN]  = { "WARN",  "<warn>",  LOG_WARNING, G_LOG_LEVEL_WARNING, FALSE },
-	[LOGL_ERR]   = { "ERR",   "<error>", LOG_ERR,     G_LOG_LEVEL_WARNING, TRUE  },
-	[_LOGL_OFF]  = { "OFF",   NULL,      0,           0,                   FALSE },
-};
-
-static const LogDesc domain_descs[] = {
-	{ LOGD_PLATFORM,  "PLATFORM" },
-	{ LOGD_RFKILL,    "RFKILL" },
-	{ LOGD_ETHER,     "ETHER" },
-	{ LOGD_WIFI,      "WIFI" },
-	{ LOGD_BT,        "BT" },
-	{ LOGD_MB,        "MB" },
-	{ LOGD_DHCP4,     "DHCP4" },
-	{ LOGD_DHCP6,     "DHCP6" },
-	{ LOGD_PPP,       "PPP" },
-	{ LOGD_WIFI_SCAN, "WIFI_SCAN" },
-	{ LOGD_IP4,       "IP4" },
-	{ LOGD_IP6,       "IP6" },
-	{ LOGD_AUTOIP4,   "AUTOIP4" },
-	{ LOGD_DNS,       "DNS" },
-	{ LOGD_VPN,       "VPN" },
-	{ LOGD_SHARING,   "SHARING" },
-	{ LOGD_SUPPLICANT,"SUPPLICANT" },
-	{ LOGD_AGENTS,    "AGENTS" },
-	{ LOGD_SETTINGS,  "SETTINGS" },
-	{ LOGD_SUSPEND,   "SUSPEND" },
-	{ LOGD_CORE,      "CORE" },
-	{ LOGD_DEVICE,    "DEVICE" },
-	{ LOGD_OLPC,      "OLPC" },
-	{ LOGD_INFINIBAND,"INFINIBAND" },
-	{ LOGD_FIREWALL,  "FIREWALL" },
-	{ LOGD_ADSL,      "ADSL" },
-	{ LOGD_BOND,      "BOND" },
-	{ LOGD_VLAN,      "VLAN" },
-	{ LOGD_BRIDGE,    "BRIDGE" },
-	{ LOGD_DBUS_PROPS,"DBUS_PROPS" },
-	{ LOGD_TEAM,      "TEAM" },
-	{ LOGD_CONCHECK,  "CONCHECK" },
-	{ LOGD_DCB,       "DCB" },
-	{ LOGD_DISPATCH,  "DISPATCH" },
-	{ LOGD_AUDIT,     "AUDIT" },
-	{ 0, NULL }
+static struct {
+	NMLogLevel log_level;
+	NMLogDomain logging[_LOGL_N_REAL];
+	gboolean logging_set_up;
+	enum {
+		LOG_BACKEND_GLIB,
+		LOG_BACKEND_SYSLOG,
+		LOG_BACKEND_JOURNAL,
+		LOG_BACKEND_JOURNAL_SYSLOG_STYLE,
+	} log_backend;
+	char *logging_domains_to_string;
+	const LogLevelDesc level_desc[_LOGL_N];
+
+#define _DOMAIN_DESC_LEN 36
+	/* Would be nice to use C99 flexible array member here,
+	 * but that feature doesn't seem well supported. */
+	const LogDesc domain_desc[_DOMAIN_DESC_LEN];
+} global = {
+	.log_level = LOGL_INFO,
+	.log_backend = LOG_BACKEND_GLIB,
+	.level_desc = {
+		[LOGL_TRACE] = { "TRACE", "<trace>", LOG_DEBUG,   G_LOG_LEVEL_DEBUG,   TRUE  },
+		[LOGL_DEBUG] = { "DEBUG", "<debug>", LOG_INFO,    G_LOG_LEVEL_DEBUG,   TRUE  },
+		[LOGL_INFO]  = { "INFO",  "<info>",  LOG_INFO,    G_LOG_LEVEL_MESSAGE, FALSE },
+		[LOGL_WARN]  = { "WARN",  "<warn>",  LOG_WARNING, G_LOG_LEVEL_WARNING, FALSE },
+		[LOGL_ERR]   = { "ERR",   "<error>", LOG_ERR,     G_LOG_LEVEL_WARNING, TRUE  },
+		[_LOGL_OFF]  = { "OFF",   NULL,      0,           0,                   FALSE },
+		[_LOGL_KEEP] = { "KEEP",  NULL,      0,           0,                   FALSE },
+	},
+	.domain_desc = {
+		{ LOGD_PLATFORM,  "PLATFORM" },
+		{ LOGD_RFKILL,    "RFKILL" },
+		{ LOGD_ETHER,     "ETHER" },
+		{ LOGD_WIFI,      "WIFI" },
+		{ LOGD_BT,        "BT" },
+		{ LOGD_MB,        "MB" },
+		{ LOGD_DHCP4,     "DHCP4" },
+		{ LOGD_DHCP6,     "DHCP6" },
+		{ LOGD_PPP,       "PPP" },
+		{ LOGD_WIFI_SCAN, "WIFI_SCAN" },
+		{ LOGD_IP4,       "IP4" },
+		{ LOGD_IP6,       "IP6" },
+		{ LOGD_AUTOIP4,   "AUTOIP4" },
+		{ LOGD_DNS,       "DNS" },
+		{ LOGD_VPN,       "VPN" },
+		{ LOGD_SHARING,   "SHARING" },
+		{ LOGD_SUPPLICANT,"SUPPLICANT" },
+		{ LOGD_AGENTS,    "AGENTS" },
+		{ LOGD_SETTINGS,  "SETTINGS" },
+		{ LOGD_SUSPEND,   "SUSPEND" },
+		{ LOGD_CORE,      "CORE" },
+		{ LOGD_DEVICE,    "DEVICE" },
+		{ LOGD_OLPC,      "OLPC" },
+		{ LOGD_INFINIBAND,"INFINIBAND" },
+		{ LOGD_FIREWALL,  "FIREWALL" },
+		{ LOGD_ADSL,      "ADSL" },
+		{ LOGD_BOND,      "BOND" },
+		{ LOGD_VLAN,      "VLAN" },
+		{ LOGD_BRIDGE,    "BRIDGE" },
+		{ LOGD_DBUS_PROPS,"DBUS_PROPS" },
+		{ LOGD_TEAM,      "TEAM" },
+		{ LOGD_CONCHECK,  "CONCHECK" },
+		{ LOGD_DCB,       "DCB" },
+		{ LOGD_DISPATCH,  "DISPATCH" },
+		{ LOGD_AUDIT,     "AUDIT" },
+		{ 0, NULL }
+		/* keep _DOMAIN_DESC_LEN in sync */
+	},
 };
 
 /* We have more then 32 logging domains. Assert that it compiles to a 64 bit sized enum */
@@ -131,11 +142,15 @@ G_STATIC_ASSERT (sizeof (NMLogDomain) >= sizeof (guint64));
 
 /************************************************************************/
 
+static char *_domains_to_string (gboolean include_level_override);
+
+/************************************************************************/
+
 static void
 _ensure_initialized (void)
 {
-	if (G_UNLIKELY (!logging_set_up))
-		nm_logging_setup ("INFO", "DEFAULT", NULL, NULL);
+	if (G_UNLIKELY (!global.logging_set_up))
+		nm_logging_setup ("INFO", LOGD_DEFAULT_STRING, NULL, NULL);
 }
 
 static gboolean
@@ -145,8 +160,8 @@ match_log_level (const char  *level,
 {
 	int i;
 
-	for (i = 0; i < G_N_ELEMENTS (level_desc); i++) {
-		if (!g_ascii_strcasecmp (level_desc[i].name, level)) {
+	for (i = 0; i < G_N_ELEMENTS (global.level_desc); i++) {
+		if (!g_ascii_strcasecmp (global.level_desc[i].name, level)) {
 			*out_level = i;
 			return TRUE;
 		}
@@ -164,15 +179,24 @@ nm_logging_setup (const char  *level,
                   GError     **error)
 {
 	GString *unrecognized = NULL;
-	NMLogDomain new_logging[G_N_ELEMENTS (logging)];
-	NMLogLevel new_log_level = log_level;
+	NMLogDomain new_logging[G_N_ELEMENTS (global.logging)];
+	NMLogLevel new_log_level = global.log_level;
 	char **tmp, **iter;
 	int i;
+	gboolean had_platform_debug;
+	gs_free char *domains_free = NULL;
 
 	g_return_val_if_fail (!bad_domains || !*bad_domains, FALSE);
 	g_return_val_if_fail (!error || !*error, FALSE);
 
-	logging_set_up = TRUE;
+	/* domains */
+	if (!domains || !*domains) {
+		domains = global.logging_set_up
+		          ? (domains_free = _domains_to_string (FALSE))
+		          : LOGD_DEFAULT_STRING;
+	}
+
+	global.logging_set_up = TRUE;
 
 	for (i = 0; i < G_N_ELEMENTS (new_logging); i++)
 		new_logging[i] = 0;
@@ -181,12 +205,13 @@ nm_logging_setup (const char  *level,
 	if (level && *level) {
 		if (!match_log_level (level, &new_log_level, error))
 			return FALSE;
+		if (new_log_level == _LOGL_KEEP) {
+			new_log_level = global.log_level;
+			for (i = 0; i < G_N_ELEMENTS (new_logging); i++)
+				new_logging[i] = global.logging[i];
+		}
 	}
 
-	/* domains */
-	if (!domains || !*domains)
-		domains = log_domains ? log_domains : "DEFAULT";
-
 	tmp = g_strsplit_set (domains, ", ", 0);
 	for (iter = tmp; iter && *iter; iter++) {
 		const LogDesc *diter;
@@ -226,7 +251,7 @@ nm_logging_setup (const char  *level,
 			continue;
 
 		else {
-			for (diter = &domain_descs[0]; diter->name; diter++) {
+			for (diter = &global.domain_desc[0]; diter->name; diter++) {
 				if (!g_ascii_strcasecmp (diter->name, *iter)) {
 					bits = diter->num;
 					break;
@@ -249,25 +274,35 @@ nm_logging_setup (const char  *level,
 			}
 		}
 
-		for (i = 0; i < G_N_ELEMENTS (new_logging); i++) {
-			if (i < domain_log_level)
-				new_logging[i] &= ~bits;
-			else
-				new_logging[i] |= bits;
+		if (domain_log_level == _LOGL_KEEP) {
+			for (i = 0; i < G_N_ELEMENTS (new_logging); i++)
+				new_logging[i] = (new_logging[i] & ~bits) | (global.logging[i] & bits);
+		} else {
+			for (i = 0; i < G_N_ELEMENTS (new_logging); i++) {
+				if (i < domain_log_level)
+					new_logging[i] &= ~bits;
+				else
+					new_logging[i] |= bits;
+			}
 		}
 	}
 	g_strfreev (tmp);
 
-	if (log_domains != (char *)domains) {
-		g_free (log_domains);
-		log_domains = g_strdup (domains);
-	}
+	g_clear_pointer (&global.logging_domains_to_string, g_free);
 
-	g_clear_pointer (&logging_domains_to_string, g_free);
+	had_platform_debug = nm_logging_enabled (LOGL_DEBUG, LOGD_PLATFORM);
 
-	log_level = new_log_level;
+	global.log_level = new_log_level;
 	for (i = 0; i < G_N_ELEMENTS (new_logging); i++)
-		logging[i] = new_logging[i];
+		global.logging[i] = new_logging[i];
+
+	if (   had_platform_debug
+	    && !nm_logging_enabled (LOGL_DEBUG, LOGD_PLATFORM)) {
+		/* when debug logging is enabled, platform will cache all access to
+		 * sysctl. When the user disables debug-logging, we want to clear that
+		 * cache right away. */
+		_nm_linux_platform_sysctl_clear_cache ();
+	}
 
 	if (unrecognized)
 		*bad_domains = g_string_free (unrecognized, FALSE);
@@ -278,7 +313,7 @@ nm_logging_setup (const char  *level,
 const char *
 nm_logging_level_to_string (void)
 {
-	return level_desc[log_level].name;
+	return global.level_desc[global.log_level].name;
 }
 
 const char *
@@ -290,10 +325,10 @@ nm_logging_all_levels_to_string (void)
 		int i;
 
 		str = g_string_new (NULL);
-		for (i = 0; i < G_N_ELEMENTS (level_desc); i++) {
+		for (i = 0; i < G_N_ELEMENTS (global.level_desc); i++) {
 			if (str->len)
 				g_string_append_c (str, ',');
-			g_string_append (str, level_desc[i].name);
+			g_string_append (str, global.level_desc[i].name);
 		}
 	}
 
@@ -305,45 +340,54 @@ nm_logging_domains_to_string (void)
 {
 	_ensure_initialized ();
 
-	if (G_UNLIKELY (!logging_domains_to_string)) {
-		const LogDesc *diter;
-		GString *str;
-		int i;
+	if (G_UNLIKELY (!global.logging_domains_to_string))
+		global.logging_domains_to_string = _domains_to_string (TRUE);
 
-		/* We don't just return g_strdup (log_domains) because we want to expand
-		 * "DEFAULT" and "ALL".
-		 */
+	return global.logging_domains_to_string;
+}
 
-		str = g_string_sized_new (75);
-		for (diter = &domain_descs[0]; diter->name; diter++) {
-			/* If it's set for any lower level, it will also be set for LOGL_ERR */
-			if (!(diter->num & logging[LOGL_ERR]))
-				continue;
+static char *
+_domains_to_string (gboolean include_level_override)
+{
+	const LogDesc *diter;
+	GString *str;
+	int i;
 
-			if (str->len)
-				g_string_append_c (str, ',');
-			g_string_append (str, diter->name);
+	/* We don't just return g_strdup (global.log_domains) because we want to expand
+	 * "DEFAULT" and "ALL".
+	 */
 
-			/* Check if it's logging at a lower level than the default. */
-			for (i = 0; i < log_level; i++) {
-				if (diter->num & logging[i]) {
-					g_string_append_printf (str, ":%s", level_desc[i].name);
-					break;
-				}
+	str = g_string_sized_new (75);
+	for (diter = &global.domain_desc[0]; diter->name; diter++) {
+		/* If it's set for any lower level, it will also be set for LOGL_ERR */
+		if (!(diter->num & global.logging[LOGL_ERR]))
+			continue;
+
+		if (str->len)
+			g_string_append_c (str, ',');
+		g_string_append (str, diter->name);
+
+		if (!include_level_override)
+			continue;
+
+		/* Check if it's logging at a lower level than the default. */
+		for (i = 0; i < global.log_level; i++) {
+			if (diter->num & global.logging[i]) {
+				g_string_append_printf (str, ":%s", global.level_desc[i].name);
+				break;
 			}
-			/* Check if it's logging at a higher level than the default. */
-			if (!(diter->num & logging[log_level])) {
-				for (i = log_level + 1; i < G_N_ELEMENTS (logging); i++) {
-					if (diter->num & logging[i]) {
-						g_string_append_printf (str, ":%s", level_desc[i].name);
-						break;
-					}
+		}
+		/* Check if it's logging at a higher level than the default. */
+		if (!(diter->num & global.logging[global.log_level])) {
+			for (i = global.log_level + 1; i < G_N_ELEMENTS (global.logging); i++) {
+				if (diter->num & global.logging[i]) {
+					g_string_append_printf (str, ":%s", global.level_desc[i].name);
+					break;
 				}
 			}
 		}
-		logging_domains_to_string = g_string_free (str, FALSE);
 	}
-	return logging_domains_to_string;
+	return g_string_free (str, FALSE);
 }
 
 const char *
@@ -355,7 +399,7 @@ nm_logging_all_domains_to_string (void)
 		const LogDesc *diter;
 
 		str = g_string_new (LOGD_DEFAULT_STRING);
-		for (diter = &domain_descs[0]; diter->name; diter++) {
+		for (diter = &global.domain_desc[0]; diter->name; diter++) {
 			g_string_append_c (str, ',');
 			g_string_append (str, diter->name);
 			if (diter->num == LOGD_DHCP6)
@@ -372,12 +416,12 @@ nm_logging_all_domains_to_string (void)
 gboolean
 nm_logging_enabled (NMLogLevel level, NMLogDomain domain)
 {
-	if ((guint) level >= G_N_ELEMENTS (logging))
+	if ((guint) level >= G_N_ELEMENTS (global.logging))
 		g_return_val_if_reached (FALSE);
 
 	_ensure_initialized ();
 
-	return !!(logging[level] & domain);
+	return !!(global.logging[level] & domain);
 }
 
 #if SYSTEMD_JOURNAL
@@ -422,12 +466,12 @@ _nm_log_impl (const char *file,
 	char *fullmsg = NULL;
 	GTimeVal tv;
 
-	if ((guint) level >= G_N_ELEMENTS (logging))
+	if ((guint) level >= G_N_ELEMENTS (global.logging))
 		g_return_if_reached ();
 
 	_ensure_initialized ();
 
-	if (!(logging[level] & domain))
+	if (!(global.logging[level] & domain))
 		return;
 
 	/* Make sure that %m maps to the specified error */
@@ -441,7 +485,7 @@ _nm_log_impl (const char *file,
 	msg = g_strdup_vprintf (fmt, args);
 	va_end (args);
 
-	switch (log_backend) {
+	switch (global.log_backend) {
 #if SYSTEMD_JOURNAL
 	case LOG_BACKEND_JOURNAL:
 	case LOG_BACKEND_JOURNAL_SYSLOG_STYLE:
@@ -456,13 +500,13 @@ _nm_log_impl (const char *file,
 			now = nm_utils_get_monotonic_timestamp_ns ();
 			boottime = nm_utils_monotonic_timestamp_as_boottime (now, 1);
 
-			_iovec_set_format (iov, iov_free, i_field++, "PRIORITY=%d", level_desc[level].syslog_level);
-			if (   log_backend == LOG_BACKEND_JOURNAL_SYSLOG_STYLE
-			    && level_desc[level].full_details) {
+			_iovec_set_format (iov, iov_free, i_field++, "PRIORITY=%d", global.level_desc[level].syslog_level);
+			if (   global.log_backend == LOG_BACKEND_JOURNAL_SYSLOG_STYLE
+			    && global.level_desc[level].full_details) {
 				g_get_current_time (&tv);
-				_iovec_set_format (iov, iov_free, i_field++, "MESSAGE=%-7s [%ld.%06ld] [%s:%u] %s(): %s", level_desc[level].level_str, tv.tv_sec, tv.tv_usec, file, line, func, msg);
+				_iovec_set_format (iov, iov_free, i_field++, "MESSAGE=%-7s [%ld.%06ld] [%s:%u] %s(): %s", global.level_desc[level].level_str, tv.tv_sec, tv.tv_usec, file, line, func, msg);
 			} else
-				_iovec_set_format (iov, iov_free, i_field++, "MESSAGE=%-7s %s", level_desc[level].level_str, msg);
+				_iovec_set_format (iov, iov_free, i_field++, "MESSAGE=%-7s %s", global.level_desc[level].level_str, msg);
 			_iovec_set_literal_string (iov, iov_free, i_field++, "SYSLOG_IDENTIFIER=" G_LOG_DOMAIN);
 			_iovec_set_format (iov, iov_free, i_field++, "SYSLOG_PID=%ld", (long) getpid ());
 			{
@@ -471,9 +515,9 @@ _nm_log_impl (const char *file,
 				const char *s_domain_1 = NULL;
 				GString *s_domain_all = NULL;
 				NMLogDomain dom_all = domain;
-				NMLogDomain dom = dom_all & logging[level];
+				NMLogDomain dom = dom_all & global.logging[level];
 
-				for (diter = &domain_descs[0]; diter->name; diter++) {
+				for (diter = &global.domain_desc[0]; diter->name; diter++) {
 					if (!NM_FLAGS_HAS (dom_all, diter->num))
 						continue;
 
@@ -507,7 +551,7 @@ _nm_log_impl (const char *file,
 				} else
 					_iovec_set_format (iov, iov_free, i_field++, "NM_LOG_DOMAINS=%s", s_domain_1);
 			}
-			_iovec_set_format (iov, iov_free, i_field++, "NM_LOG_LEVEL=%s", level_desc[level].name);
+			_iovec_set_format (iov, iov_free, i_field++, "NM_LOG_LEVEL=%s", global.level_desc[level].name);
 			_iovec_set_format (iov, iov_free, i_field++, "CODE_FUNC=%s", func);
 			_iovec_set_format (iov, iov_free, i_field++, "CODE_FILE=%s", file);
 			_iovec_set_format (iov, iov_free, i_field++, "CODE_LINE=%u", line);
@@ -529,16 +573,16 @@ _nm_log_impl (const char *file,
 		break;
 #endif
 	default:
-		if (level_desc[level].full_details) {
+		if (global.level_desc[level].full_details) {
 			g_get_current_time (&tv);
-			fullmsg = g_strdup_printf ("%-7s [%ld.%06ld] [%s:%u] %s(): %s", level_desc[level].level_str, tv.tv_sec, tv.tv_usec, file, line, func, msg);
+			fullmsg = g_strdup_printf ("%-7s [%ld.%06ld] [%s:%u] %s(): %s", global.level_desc[level].level_str, tv.tv_sec, tv.tv_usec, file, line, func, msg);
 		} else
-			fullmsg = g_strdup_printf ("%-7s %s", level_desc[level].level_str, msg);
+			fullmsg = g_strdup_printf ("%-7s %s", global.level_desc[level].level_str, msg);
 
-		if (log_backend == LOG_BACKEND_SYSLOG)
-			syslog (level_desc[level].syslog_level, "%s", fullmsg);
+		if (global.log_backend == LOG_BACKEND_SYSLOG)
+			syslog (global.level_desc[level].syslog_level, "%s", fullmsg);
 		else
-			g_log (G_LOG_DOMAIN, level_desc[level].g_log_level, "%s", fullmsg);
+			g_log (G_LOG_DOMAIN, global.level_desc[level].g_log_level, "%s", fullmsg);
 		break;
 	}
 
@@ -578,7 +622,7 @@ nm_log_handler (const gchar *log_domain,
 		break;
 	}
 
-	switch (log_backend) {
+	switch (global.log_backend) {
 #if SYSTEMD_JOURNAL
 	case LOG_BACKEND_JOURNAL:
 	case LOG_BACKEND_JOURNAL_SYSLOG_STYLE:
@@ -610,28 +654,28 @@ nm_log_handler (const gchar *log_domain,
 void
 nm_logging_syslog_openlog (const char *logging_backend)
 {
-	if (log_backend != LOG_BACKEND_GLIB)
+	if (global.log_backend != LOG_BACKEND_GLIB)
 		g_return_if_reached ();
 
 	if (!logging_backend)
 		logging_backend = ""NM_CONFIG_LOGGING_BACKEND_DEFAULT;
 
 	if (strcmp (logging_backend, "debug") == 0) {
-		log_backend = LOG_BACKEND_SYSLOG;
+		global.log_backend = LOG_BACKEND_SYSLOG;
 		openlog (G_LOG_DOMAIN, LOG_CONS | LOG_PERROR | LOG_PID, LOG_USER);
 #if SYSTEMD_JOURNAL
 	} else if (strcmp (logging_backend, "syslog") != 0) {
 		if (strcmp (logging_backend, "journal-syslog-style") != 0)
-			log_backend = LOG_BACKEND_JOURNAL;
+			global.log_backend = LOG_BACKEND_JOURNAL;
 		else
-			log_backend = LOG_BACKEND_JOURNAL_SYSLOG_STYLE;
+			global.log_backend = LOG_BACKEND_JOURNAL_SYSLOG_STYLE;
 
 		/* ensure we read a monotonic timestamp. Reading the timestamp the first
 		 * time causes a logging message. We don't want to do that during _nm_log_impl. */
 		nm_utils_get_monotonic_timestamp_ns ();
 #endif
 	} else {
-		log_backend = LOG_BACKEND_SYSLOG;
+		global.log_backend = LOG_BACKEND_SYSLOG;
 		openlog (G_LOG_DOMAIN, LOG_PID, LOG_DAEMON);
 	}
 
diff --git a/src/nm-logging.h b/src/nm-logging.h
index db9f0b1557..b54078186e 100644
--- a/src/nm-logging.h
+++ b/src/nm-logging.h
@@ -94,6 +94,7 @@ typedef enum  { /*< skip >*/
 	_LOGL_N_REAL, /* the number of actual logging levels */
 
 	_LOGL_OFF = _LOGL_N_REAL, /* special logging level that is always disabled. */
+	_LOGL_KEEP,               /* special logging level to indicate that the logging level should not be changed. */
 
 	_LOGL_N, /* the number of logging levels including "OFF" */
 } NMLogLevel;
diff --git a/src/platform/nm-linux-platform.c b/src/platform/nm-linux-platform.c
index 2daa1aec46..76d74da0bd 100644
--- a/src/platform/nm-linux-platform.c
+++ b/src/platform/nm-linux-platform.c
@@ -731,6 +731,7 @@ struct _NMLinuxPlatformPrivate {
 	GIOChannel *event_channel;
 	guint event_id;
 
+	gboolean sysctl_get_warned;
 	GHashTable *sysctl_get_prev_values;
 
 	GUdevClient *udev_client;
@@ -2546,15 +2547,32 @@ sysctl_set (NMPlatform *platform, const char *path, const char *value)
 	return (nwrote == len);
 }
 
+static GSList *sysctl_clear_cache_list;
+
+void
+_nm_linux_platform_sysctl_clear_cache (void)
+{
+	while (sysctl_clear_cache_list) {
+		NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE (sysctl_clear_cache_list->data);
+
+		sysctl_clear_cache_list = g_slist_delete_link (sysctl_clear_cache_list, sysctl_clear_cache_list);
+
+		g_hash_table_destroy (priv->sysctl_get_prev_values);
+		priv->sysctl_get_prev_values = NULL;
+		priv->sysctl_get_warned = FALSE;
+	}
+}
+
 static void
 _log_dbg_sysctl_get_impl (NMPlatform *platform, const char *path, const char *contents)
 {
 	NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE (platform);
 	const char *prev_value = NULL;
 
-	if (!priv->sysctl_get_prev_values)
+	if (!priv->sysctl_get_prev_values) {
+		sysctl_clear_cache_list = g_slist_prepend (sysctl_clear_cache_list, platform);
 		priv->sysctl_get_prev_values = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
-	else
+	} else
 		prev_value = g_hash_table_lookup (priv->sysctl_get_prev_values, path);
 
 	if (prev_value) {
@@ -2574,20 +2592,18 @@ _log_dbg_sysctl_get_impl (NMPlatform *platform, const char *path, const char *co
 		g_free (contents_escaped);
 		g_hash_table_insert (priv->sysctl_get_prev_values, g_strdup (path), g_strdup (contents));
 	}
+
+	if (   !priv->sysctl_get_warned
+	    && g_hash_table_size (priv->sysctl_get_prev_values) > 50000) {
+		_LOGW ("sysctl: the internal cache for debug-logging of sysctl values grew pretty large. You can clear it by disabling debug-logging: `nmcli general logging level KEEP domains PLATFORM:INFO`.");
+		priv->sysctl_get_warned = TRUE;
+	}
 }
 
 #define _log_dbg_sysctl_get(platform, path, contents) \
 	G_STMT_START { \
-		if (_LOGD_ENABLED ()) { \
+		if (_LOGD_ENABLED ()) \
 			_log_dbg_sysctl_get_impl (platform, path, contents); \
-		} else { \
-			NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE (platform); \
-			\
-			if (priv->sysctl_get_prev_values) { \
-				g_hash_table_destroy (priv->sysctl_get_prev_values); \
-				priv->sysctl_get_prev_values = NULL; \
-			} \
-		} \
 	} G_STMT_END
 
 static char *
@@ -5029,8 +5045,10 @@ nm_linux_platform_finalize (GObject *object)
 	g_object_unref (priv->udev_client);
 	g_hash_table_unref (priv->wifi_data);
 
-	if (priv->sysctl_get_prev_values)
+	if (priv->sysctl_get_prev_values) {
+		sysctl_clear_cache_list = g_slist_remove (sysctl_clear_cache_list, object);
 		g_hash_table_destroy (priv->sysctl_get_prev_values);
+	}
 
 	G_OBJECT_CLASS (nm_linux_platform_parent_class)->finalize (object);
 }
diff --git a/src/platform/nm-linux-platform.h b/src/platform/nm-linux-platform.h
index a9e2cd82f9..81f9c73871 100644
--- a/src/platform/nm-linux-platform.h
+++ b/src/platform/nm-linux-platform.h
@@ -50,4 +50,6 @@ GType nm_linux_platform_get_type (void);
 
 void nm_linux_platform_setup (void);
 
+void _nm_linux_platform_sysctl_clear_cache (void);
+
 #endif /* __NETWORKMANAGER_LINUX_PLATFORM_H__ */