fdd2c1f4e2
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. Skip dumping if another context is already dumping. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-2-john.ogness@linutronix.de
57 lines
1.1 KiB
C
57 lines
1.1 KiB
C
// 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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#include <shared/kern.h>
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#include <os.h>
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static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
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enum kmsg_dump_reason reason)
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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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if (!console_trylock())
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return;
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for_each_console(con) {
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if(strcmp(con->name, "tty") == 0 &&
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(con->flags & (CON_ENABLED | CON_CONSDEV)) != 0) {
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break;
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}
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}
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console_unlock();
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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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printf("kmsg_dump:\n");
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while (kmsg_dump_get_line(dumper, 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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spin_unlock_irqrestore(&lock, flags);
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}
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static struct kmsg_dumper kmsg_dumper = {
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.dump = kmsg_dumper_stdout
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};
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int __init kmsg_dumper_stdout_init(void)
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{
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return kmsg_dump_register(&kmsg_dumper);
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}
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__uml_postsetup(kmsg_dumper_stdout_init);
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