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kernel/amd64/debug.c

@@ -26,13 +26,9 @@ static bool amd64_debug_serial_tx_empty (void) {
 
 /* Write a single character to serial */
 static void amd64_debug_serial_write (char x) {
-  spin_lock (&serial_lock);
-
   while (!amd64_debug_serial_tx_empty ())
     ;
   amd64_io_outb (PORT_COM1, (uint8_t)x);
-
-  spin_unlock (&serial_lock);
 }
 
 /*
@@ -54,10 +50,14 @@ void debugprintf (const char* fmt, ...) {
 
   const char* p = buffer;
 
+  spin_lock (&serial_lock);
+
   while (*p) {
     amd64_debug_serial_write (*p);
     p++;
   }
+
+  spin_unlock (&serial_lock);
 }
 
 /* Initialize serial */