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55 lines
1.5 KiB
Diff
55 lines
1.5 KiB
Diff
From: John Ogness <john.ogness@linutronix.de>
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Date: Mon, 21 Dec 2020 11:10:03 +0106
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Subject: [PATCH 11/28] um: synchronize kmsg_dumper
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The kmsg_dumper can be called from any context and CPU, possibly
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from multiple CPUs simultaneously. Since a static buffer is used
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to retrieve the kernel logs, this buffer must be protected against
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simultaneous dumping.
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Cc: Richard Weinberger <richard@nod.at>
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Reviewed-by: Petr Mladek <pmladek@suse.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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arch/um/kernel/kmsg_dump.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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--- a/arch/um/kernel/kmsg_dump.c
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+++ b/arch/um/kernel/kmsg_dump.c
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@@ -1,5 +1,6 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/kmsg_dump.h>
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+#include <linux/spinlock.h>
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#include <linux/console.h>
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#include <linux/string.h>
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#include <shared/init.h>
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@@ -10,8 +11,10 @@ static void kmsg_dumper_stdout(struct km
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enum kmsg_dump_reason reason,
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struct kmsg_dumper_iter *iter)
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{
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+ static DEFINE_SPINLOCK(lock);
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static char line[1024];
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struct console *con;
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+ unsigned long flags;
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size_t len = 0;
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/* only dump kmsg when no console is available */
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@@ -30,11 +33,16 @@ static void kmsg_dumper_stdout(struct km
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if (con)
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return;
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+ if (!spin_trylock_irqsave(&lock, flags))
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+ return;
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+
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printf("kmsg_dump:\n");
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while (kmsg_dump_get_line(iter, true, line, sizeof(line), &len)) {
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line[len] = '\0';
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printf("%s", line);
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}
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+
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+ spin_unlock_irqrestore(&lock, flags);
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}
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static struct kmsg_dumper kmsg_dumper = {
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