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-rw-r--r--debian/patches-rt/0091-um-synchronize-kmsg_dumper.patch61
1 files changed, 61 insertions, 0 deletions
diff --git a/debian/patches-rt/0091-um-synchronize-kmsg_dumper.patch b/debian/patches-rt/0091-um-synchronize-kmsg_dumper.patch
new file mode 100644
index 000000000..88b6f08ca
--- /dev/null
+++ b/debian/patches-rt/0091-um-synchronize-kmsg_dumper.patch
@@ -0,0 +1,61 @@
+From 7790fa6baa700a285007a6e8ddf99393ba72acc2 Mon Sep 17 00:00:00 2001
+From: John Ogness <john.ogness@linutronix.de>
+Date: Mon, 21 Dec 2020 11:10:03 +0106
+Subject: [PATCH 091/323] um: synchronize kmsg_dumper
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+The kmsg_dumper can be called from any context and CPU, possibly
+from multiple CPUs simultaneously. Since a static buffer is used
+to retrieve the kernel logs, this buffer must be protected against
+simultaneous dumping.
+
+Cc: Richard Weinberger <richard@nod.at>
+Signed-off-by: John Ogness <john.ogness@linutronix.de>
+Reviewed-by: Petr Mladek <pmladek@suse.com>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ arch/um/kernel/kmsg_dump.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
+index f38349ad00ea..173999422ed8 100644
+--- a/arch/um/kernel/kmsg_dump.c
++++ b/arch/um/kernel/kmsg_dump.c
+@@ -1,5 +1,6 @@
+ // SPDX-License-Identifier: GPL-2.0
+ #include <linux/kmsg_dump.h>
++#include <linux/spinlock.h>
+ #include <linux/console.h>
+ #include <shared/init.h>
+ #include <shared/kern.h>
+@@ -9,8 +10,10 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason,
+ struct kmsg_dumper_iter *iter)
+ {
++ static DEFINE_SPINLOCK(lock);
+ static char line[1024];
+ struct console *con;
++ unsigned long flags;
+ size_t len = 0;
+
+ /* only dump kmsg when no console is available */
+@@ -25,11 +28,16 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
+ if (con)
+ return;
+
++ if (!spin_trylock_irqsave(&lock, flags))
++ return;
++
+ printf("kmsg_dump:\n");
+ 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 = {
+--
+2.43.0
+