1 files changed, 33 insertions, 11 deletions

diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index e4abac6c9727..fc0f543d1d8e 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -1,41 +1,63 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/kmsg_dump.h>
+#include <linux/spinlock.h>
 #include <linux/console.h>
+#include <linux/string.h>
 #include <shared/init.h>
 #include <shared/kern.h>
 #include <os.h>
 
 static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
-				enum kmsg_dump_reason reason)
+				struct kmsg_dump_detail *detail)
 {
+	static struct kmsg_dump_iter iter;
+	static DEFINE_SPINLOCK(lock);
 	static char line[1024];
 	struct console *con;
+	unsigned long flags;
 	size_t len = 0;
+	int cookie;
 
-	/* only dump kmsg when no console is available */
-	if (!console_trylock())
-		return;
-
-	for_each_console(con)
-		break;
-
-	console_unlock();
+	/*
+	 * If no consoles are available to output crash information, dump
+	 * the kmsg buffer to stdout.
+	 */
 
+	cookie = console_srcu_read_lock();
+	for_each_console_srcu(con) {
+		/*
+		 * The ttynull console and disabled consoles are ignored
+		 * since they cannot output. All other consoles are
+		 * expected to output the crash information.
+		 */
+		if (strcmp(con->name, "ttynull") != 0 &&
+		    console_is_usable(con, console_srcu_read_flags(con), true)) {
+			break;
+		}
+	}
+	console_srcu_read_unlock(cookie);
 	if (con)
 		return;
 
+	if (!spin_trylock_irqsave(&lock, flags))
+		return;
+
+	kmsg_dump_rewind(&iter);
+
 	printf("kmsg_dump:\n");
-	while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) {
+	while (kmsg_dump_get_line(&iter, true, line, sizeof(line), &len)) {
 		line[len] = '\0';
 		printf("%s", line);
 	}
+
+	spin_unlock_irqrestore(&lock, flags);
 }
 
 static struct kmsg_dumper kmsg_dumper = {
 	.dump = kmsg_dumper_stdout
 };
 
-int __init kmsg_dumper_stdout_init(void)
+static int __init kmsg_dumper_stdout_init(void)
 {
 	return kmsg_dump_register(&kmsg_dumper);
 }