Changeset 90dd8aee in mainline for kernel/generic/src/console/console.c

Timestamp:

2025-04-10T17:55:36Z (4 days ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master

Children:

8165a7a, c0d814a

Parents:

c55ab66

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-10 11:33:46)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-10 17:55:36)

Message:

Introduce a console lock to prevent line splitting in kernel output

It is a common occurrence to see broken lines on screen or in serial
output due to bad timing. This is an attempt to prevent that without
breaking anything.

It could be considered a stopgap solution, since the whole console
stack deserves a better/faster implementation.

File:

• kernel/generic/src/console/console.c (modified) (3 diffs)

kernel/generic/src/console/console.c

@@ -34 +34 @@
  */
 
+#include <abi/kio.h>
+#include <arch.h>
 #include <assert.h>
+#include <atomic.h>
+#include <console/chardev.h>
 #include <console/console.h>
-#include <console/chardev.h>
-#include <sysinfo/sysinfo.h>
-#include <synch/waitq.h>
-#include <synch/spinlock.h>
-#include <typedefs.h>
+#include <ddi/ddi.h>
 #include <ddi/irq.h>
-#include <ddi/ddi.h>
+#include <errno.h>
 #include <ipc/event.h>
 #include <ipc/irq.h>
-#include <arch.h>
+#include <mm/frame.h> /* SIZE2FRAMES */
 #include <panic.h>
+#include <preemption.h>
+#include <proc/thread.h>
+#include <putchar.h>
+#include <stdatomic.h>
 #include <stdio.h>
-#include <putchar.h>
-#include <atomic.h>
+#include <stdlib.h>  /* malloc */
+#include <str.h>
+#include <synch/mutex.h>
+#include <synch/spinlock.h>
+#include <synch/waitq.h>
 #include <syscall/copy.h>
-#include <errno.h>
-#include <str.h>
-#include <stdatomic.h>
-#include <abi/kio.h>
-#include <mm/frame.h> /* SIZE2FRAMES */
-#include <stdlib.h>  /* malloc */
+#include <sysinfo/sysinfo.h>
+#include <typedefs.h>
 
 #define KIO_PAGES    8
@@ -66 +69 @@
 /** Kernel log initialized */
 static atomic_bool kio_inited = ATOMIC_VAR_INIT(false);
+
+/** A mutex for preventing interleaving of output lines from different threads.
+ * May not be held in some circumstances, so locking of any internal shared
+ * structures is still necessary.
+ */
+static MUTEX_INITIALIZE(console_mutex, MUTEX_RECURSIVE);
 
 /** First kernel log characters */
@@ -395 +404 @@
 }
 
+/** Lock console output, ensuring that lines from different threads don't
+ * interleave. Does nothing when preemption is disabled, so that debugging
+ * and error printouts in sensitive areas still work.
+ */
+void console_lock(void)
+{
+        if (!PREEMPTION_DISABLED)
+                mutex_lock(&console_mutex);
+}
+
+/** Unlocks console output. See console_lock()
+ */
+void console_unlock(void)
+{
+        if (!PREEMPTION_DISABLED)
+                mutex_unlock(&console_mutex);
+}
+
 /** @}
  */