*: Use fprintf between qemu_log_trylock/unlock

Inside qemu_log, we perform qemu_log_trylock/unlock, which need
not be done if we have already performed the lock beforehand.

Always check the result of qemu_log_trylock -- only checking
qemu_loglevel_mask races with the acquisition of the lock on
the logfile.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220417183019.755276-10-richard.henderson@linaro.org>

1 files changed, 14 insertions, 11 deletions

diff --git a/net/can/can_socketcan.c b/net/can/can_socketcan.c
index 4a505643e9..a6388563c3 100644
--- a/net/can/can_socketcan.c
+++ b/net/can/can_socketcan.c
@@ -77,18 +77,21 @@ static void can_host_socketcan_display_msg(struct qemu_can_frame *msg)
 {
     int i;
     FILE *logfile = qemu_log_trylock();
-    qemu_log("[cansocketcan]: %03X [%01d] %s %s",
-             msg->can_id & QEMU_CAN_EFF_MASK,
-             msg->can_dlc,
-             msg->can_id & QEMU_CAN_EFF_FLAG ? "EFF" : "SFF",
-             msg->can_id & QEMU_CAN_RTR_FLAG ? "RTR" : "DAT");
-
-    for (i = 0; i < msg->can_dlc; i++) {
-        qemu_log(" %02X", msg->data[i]);
+
+    if (logfile) {
+        fprintf(logfile, "[cansocketcan]: %03X [%01d] %s %s",
+                msg->can_id & QEMU_CAN_EFF_MASK,
+                msg->can_dlc,
+                msg->can_id & QEMU_CAN_EFF_FLAG ? "EFF" : "SFF",
+                msg->can_id & QEMU_CAN_RTR_FLAG ? "RTR" : "DAT");
+
+        for (i = 0; i < msg->can_dlc; i++) {
+            fprintf(logfile, " %02X", msg->data[i]);
+        }
+        fprintf(logfile, "\n");
+        qemu_log_flush();
+        qemu_log_unlock(logfile);
     }
-    qemu_log("\n");
-    qemu_log_flush();
-    qemu_log_unlock(logfile);
 }
 
 static void can_host_socketcan_read(void *opaque)