[Qemu-devel] [PATCH v8 3/9] qemu-log: Avoid function call for disabled qemu_log_mask logging

["Alex Bennée" <alex.bennee@linaro.org>]

From: Peter Maydell <peter.maydell@linaro.org>

Make qemu_log_mask() a macro which only calls the function to
do the actual work if the logging is enabled. This avoids making
a function call in possible fast paths where logging is disabled.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Andreas Färber <afaerber@suse.de>

---
v4
  - fix s-o-b tags, add r-b tag
---
 include/qemu/log.h | 13 ++++++++++---
 util/log.c         | 11 -----------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/include/qemu/log.h b/include/qemu/log.h
index 40c24fd..523c886 100644
--- a/include/qemu/log.h
+++ b/include/qemu/log.h
@@ -66,10 +66,17 @@ qemu_log_vprintf(const char *fmt, va_list va)
     }
 }
 
-/* log only if a bit is set on the current loglevel mask
+/* log only if a bit is set on the current loglevel mask:
+ * @mask: bit to check in the mask
+ * @fmt: printf-style format string
+ * @args: optional arguments for format string
  */
-void GCC_FMT_ATTR(2, 3) qemu_log_mask(int mask, const char *fmt, ...);
-
+#define qemu_log_mask(MASK, FMT, ...)                   \
+    do {                                                \
+        if (unlikely(qemu_loglevel_mask(MASK))) {       \
+            qemu_log(FMT, ## __VA_ARGS__);              \
+        }                                               \
+    } while (0)
 
 /* Maintenance: */
 
diff --git a/util/log.c b/util/log.c
index 6160b49..a0c0e53 100644
--- a/util/log.c
+++ b/util/log.c
@@ -38,17 +38,6 @@ void qemu_log(const char *fmt, ...)
     va_end(ap);
 }
 
-void qemu_log_mask(int mask, const char *fmt, ...)
-{
-    va_list ap;
-
-    va_start(ap, fmt);
-    if ((qemu_loglevel & mask) && qemu_logfile) {
-        vfprintf(qemu_logfile, fmt, ap);
-    }
-    va_end(ap);
-}
-
 /* enable or disable low levels log */
 void do_qemu_set_log(int log_flags, bool use_own_buffers)
 {
-- 
2.7.2