[Qemu-devel] [PATCH v4] block: always compile-check debug prints

[Zhou Jie <zhoujie2011@cn.fujitsu.com>]

Files with conditional debug statements should ensure that the printf is
always compiled. This prevents bitrot of the format string of the debug
statement. And switch debug output to stderr.

Signed-off-by: Zhou Jie <zhoujie2011@cn.fujitsu.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
v3 -> v4:
 * Alter commit message to add "And switch debug output to stderr".

 block/curl.c     | 10 ++++++++--
 block/sheepdog.c | 13 ++++++++-----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/block/curl.c b/block/curl.c
index 5a8f8b6..da9f5e8 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -36,10 +36,16 @@
 // #define DEBUG_VERBOSE
 
 #ifdef DEBUG_CURL
-#define DPRINTF(fmt, ...) do { printf(fmt, ## __VA_ARGS__); } while (0)
+#define DEBUG_CURL_PRINT 1
 #else
-#define DPRINTF(fmt, ...) do { } while (0)
+#define DEBUG_CURL_PRINT 0
 #endif
+#define DPRINTF(fmt, ...)                                            \
+    do {                                                             \
+        if (DEBUG_CURL_PRINT) {                                      \
+            fprintf(stderr, fmt, ## __VA_ARGS__);                    \
+        }                                                            \
+    } while (0)
 
 #if LIBCURL_VERSION_NUM >= 0x071000
 /* The multi interface timer callback was introduced in 7.16.0 */
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 33e0a33..9023686 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -294,13 +294,16 @@ static inline size_t count_data_objs(const struct SheepdogInode *inode)
 
 #undef DPRINTF
 #ifdef DEBUG_SDOG
-#define DPRINTF(fmt, args...)                                       \
-    do {                                                            \
-        fprintf(stdout, "%s %d: " fmt, __func__, __LINE__, ##args); \
-    } while (0)
+#define DEBUG_SDOG_PRINT 1
 #else
-#define DPRINTF(fmt, args...)
+#define DEBUG_SDOG_PRINT 0
 #endif
+#define DPRINTF(fmt, args...)                                           \
+    do {                                                                \
+        if (DEBUG_SDOG_PRINT) {                                         \
+            fprintf(stderr, "%s %d: " fmt, __func__, __LINE__, ##args); \
+        }                                                               \
+    } while (0)
 
 typedef struct SheepdogAIOCB SheepdogAIOCB;
 
-- 
2.5.5