Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | [PATCH printk-rework 09/12] um: synchronize kmsg_dumper | Date | Tue, 26 Jan 2021 22:21:48 +0106 |
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In preparation for removing printk's @logbuf_lock, dumpers that have assumed to be protected against parallel calls must provide their own synchronization. Add a locally static spinlock to synchronize the kmsg_dump call and temporary buffer usage.
Signed-off-by: John Ogness <john.ogness@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 = { -- 2.20.1
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