device-mapper-multipath/0064-libmultipath-simplify-dlog.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Martin Wilck <mwilck@suse.com>
Date: Sat, 26 Sep 2020 00:39:22 +0200
Subject: [PATCH] libmultipath: simplify dlog()

By checking the log level in condlog() directly, we can simplify
dlog(). Also, it's now possible to limit the log level at compile
time by setting MAX_VERBOSITY, enabling the compiler to optimize
away log messages with higher loglevel.

Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/debug.c     | 30 +++++++++++++-----------------
 libmultipath/debug.h     | 20 ++++++++++++++++----
 libmultipath/devmapper.c |  4 +++-
 tests/test-log.c         |  4 ++--
 tests/test-log.h         |  3 ++-
 5 files changed, 36 insertions(+), 25 deletions(-)

diff --git a/libmultipath/debug.c b/libmultipath/debug.c
index f9b77552..429f2699 100644
--- a/libmultipath/debug.c
+++ b/libmultipath/debug.c
@@ -18,29 +18,25 @@
 int logsink;
 int libmp_verbosity = DEFAULT_VERBOSITY;
 
-void dlog (int sink, int prio, const char * fmt, ...)
+void dlog(int prio, const char * fmt, ...)
 {
 	va_list ap;
 
 	va_start(ap, fmt);
+	if (logsink != LOGSINK_SYSLOG) {
+		if (logsink == LOGSINK_STDERR_WITH_TIME) {
+			time_t t = time(NULL);
+			struct tm *tb = localtime(&t);
+			char buff[16];
 
-	if (prio <= libmp_verbosity) {
-		if (sink != LOGSINK_SYSLOG) {
-			if (sink == LOGSINK_STDERR_WITH_TIME) {
-				time_t t = time(NULL);
-				struct tm *tb = localtime(&t);
-				char buff[16];
-
-				strftime(buff, sizeof(buff),
-					 "%b %d %H:%M:%S", tb);
-				buff[sizeof(buff)-1] = '\0';
-
-				fprintf(stderr, "%s | ", buff);
-			}
-			vfprintf(stderr, fmt, ap);
+			strftime(buff, sizeof(buff),
+				 "%b %d %H:%M:%S", tb);
+			buff[sizeof(buff)-1] = '\0';
+			fprintf(stderr, "%s | ", buff);
 		}
-		else
-			log_safe(prio + 3, fmt, ap);
+		vfprintf(stderr, fmt, ap);
 	}
+	else
+		log_safe(prio + 3, fmt, ap);
 	va_end(ap);
 }
diff --git a/libmultipath/debug.h b/libmultipath/debug.h
index b6ce70a7..705a5d73 100644
--- a/libmultipath/debug.h
+++ b/libmultipath/debug.h
@@ -1,5 +1,7 @@
-void dlog (int sink, int prio, const char * fmt, ...)
-	__attribute__((format(printf, 3, 4)));
+#ifndef _DEBUG_H
+#define _DEBUG_H
+void dlog (int prio, const char *fmt, ...)
+	__attribute__((format(printf, 2, 3)));
 
 
 #include <pthread.h>
@@ -10,11 +12,21 @@ void dlog (int sink, int prio, const char * fmt, ...)
 extern int logsink;
 extern int libmp_verbosity;
 
-#define condlog(prio, fmt, args...) \
-	dlog(logsink, prio, fmt "\n", ##args)
+#ifndef MAX_VERBOSITY
+#define MAX_VERBOSITY 4
+#endif
 
 enum {
 	LOGSINK_STDERR_WITH_TIME = 0,
 	LOGSINK_STDERR_WITHOUT_TIME = -1,
 	LOGSINK_SYSLOG = 1,
 };
+
+#define condlog(prio, fmt, args...)					\
+	do {								\
+		int __p = (prio);					\
+									\
+		if (__p <= MAX_VERBOSITY && __p <= libmp_verbosity)	\
+			dlog(__p, fmt "\n", ##args);			\
+	} while (0)
+#endif /* _DEBUG_H */
diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index f8b180e1..4977b311 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -276,7 +276,9 @@ static int dm_tgt_prereq (unsigned int *ver)
 
 static void _init_versions(void)
 {
-	dlog(logsink, 3, VERSION_STRING);
+	/* Can't use condlog here because of how VERSION_STRING is defined */
+	if (3 <= libmp_verbosity)
+		dlog(3, VERSION_STRING);
 	init_dm_library_version();
 	init_dm_drv_version();
 	init_dm_mpath_version();
diff --git a/tests/test-log.c b/tests/test-log.c
index 1c901cba..14f25b9b 100644
--- a/tests/test-log.c
+++ b/tests/test-log.c
@@ -7,8 +7,8 @@
 #include "log.h"
 #include "test-log.h"
 
-__attribute__((format(printf, 3, 0)))
-void __wrap_dlog (int sink, int prio, const char * fmt, ...)
+__attribute__((format(printf, 2, 0)))
+void __wrap_dlog (int prio, const char * fmt, ...)
 {
 	char buff[MAX_MSG_SIZE];
 	va_list ap;
diff --git a/tests/test-log.h b/tests/test-log.h
index 2c878c63..6d22cd23 100644
--- a/tests/test-log.h
+++ b/tests/test-log.h
@@ -1,7 +1,8 @@
 #ifndef _TEST_LOG_H
 #define _TEST_LOG_H
 
-void __wrap_dlog (int sink, int prio, const char * fmt, ...);
+__attribute__((format(printf, 2, 0)))
+void __wrap_dlog (int prio, const char * fmt, ...);
 void expect_condlog(int prio, char *string);
 
 #endif
-- 
2.17.2