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| author |   John Ogness <john.ogness@linutronix.de> | 2021-03-03 11:15:14 +0100 |
|---|---|---|
| committer |   Petr Mladek <pmladek@suse.com> | 2021-03-08 11:42:37 +0100 |
| commit | fdd2c1f4e2c2e2fee1d95d18b4b06bc0d15c368a (patch) | |
| tree | 675cb1c8dbc8fb10b73f5d7e3eb3218c515e3f2d /arch/um | |
| parent | Merge tag 'printk-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux (diff) | |
| download | linux-dev-fdd2c1f4e2c2e2fee1d95d18b4b06bc0d15c368a.tar.xz linux-dev-fdd2c1f4e2c2e2fee1d95d18b4b06bc0d15c368a.zip | |
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. 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
Diffstat (limited to 'arch/um')
| -rw-r--r-- | arch/um/kernel/kmsg_dump.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c index 6516ef1f8274..a765d235e50e 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> @@ -9,8 +10,10 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason) { + 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 */ @@ -29,11 +32,16 @@ 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(dumper, true, line, sizeof(line), &len)) { line[len] = '\0'; printf("%s", line); } + + spin_unlock_irqrestore(&lock, flags); } static struct kmsg_dumper kmsg_dumper = { |