diff options
Diffstat (limited to 'features/rt/um-synchronize-kmsg_dumper.patch')
| -rw-r--r-- | features/rt/um-synchronize-kmsg_dumper.patch | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/features/rt/um-synchronize-kmsg_dumper.patch b/features/rt/um-synchronize-kmsg_dumper.patch new file mode 100644 index 00000000..e966e64f --- /dev/null +++ b/features/rt/um-synchronize-kmsg_dumper.patch @@ -0,0 +1,60 @@ +From f3906ea0eeb323f758000d9ac28d7c08d769aee5 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 016/191] um: synchronize kmsg_dumper + +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 78befecb79d2..deab9b56b51f 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 <linux/string.h> + #include <shared/init.h> +@@ -10,8 +11,10 @@ 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 */ +@@ -30,11 +33,16 @@ 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 = { +-- +2.19.1 + |