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-rw-r--r--kernel/panic.c2
-rw-r--r--kernel/printk/internal.h2
-rw-r--r--kernel/printk/printk.c8
-rw-r--r--kernel/printk/printk_safe.c32
-rw-r--r--kernel/reboot.c2
5 files changed, 45 insertions, 1 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index a3c758dba15a..4cf13c37bd08 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -297,6 +297,7 @@ void panic(const char *fmt, ...)
* unfortunately means it may not be hardened to work in a
* panic situation.
*/
+ try_block_console_kthreads(10000);
smp_send_stop();
} else {
/*
@@ -304,6 +305,7 @@ void panic(const char *fmt, ...)
* kmsg_dump, we will need architecture dependent extra
* works in addition to stopping other CPUs.
*/
+ try_block_console_kthreads(10000);
crash_smp_send_stop();
}
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index d947ca6c84f9..e7d8578860ad 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -20,6 +20,8 @@ enum printk_info_flags {
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
+extern bool block_console_kthreads;
+
__printf(4, 0)
int vprintk_store(int facility, int level,
const struct dev_printk_info *dev_info,
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ea3dd55709e7..b095fb5f5f61 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -250,6 +250,9 @@ static atomic_t console_kthreads_active = ATOMIC_INIT(0);
#define console_kthread_printing_exit() \
atomic_dec(&console_kthreads_active)
+/* Block console kthreads to avoid processing new messages. */
+bool block_console_kthreads;
+
/*
* Helper macros to handle lockdep when locking/unlocking console_sem. We use
* macros instead of functions so that _RET_IP_ contains useful information.
@@ -3729,7 +3732,10 @@ static bool printer_should_wake(struct console *con, u64 seq)
return true;
if (con->blocked ||
- console_kthreads_atomically_blocked()) {
+ console_kthreads_atomically_blocked() ||
+ block_console_kthreads ||
+ system_state > SYSTEM_RUNNING ||
+ oops_in_progress) {
return false;
}
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index ef0f9a2044da..caac4de1ea59 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -8,7 +8,9 @@
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/printk.h>
+#include <linux/console.h>
#include <linux/kprobes.h>
+#include <linux/delay.h>
#include "internal.h"
@@ -50,3 +52,33 @@ asmlinkage int vprintk(const char *fmt, va_list args)
return vprintk_default(fmt, args);
}
EXPORT_SYMBOL(vprintk);
+
+/**
+ * try_block_console_kthreads() - Try to block console kthreads and
+ * make the global console_lock() avaialble
+ *
+ * @timeout_ms: The maximum time (in ms) to wait.
+ *
+ * Prevent console kthreads from starting processing new messages. Wait
+ * until the global console_lock() become available.
+ *
+ * Context: Can be called in any context.
+ */
+void try_block_console_kthreads(int timeout_ms)
+{
+ block_console_kthreads = true;
+
+ /* Do not wait when the console lock could not be safely taken. */
+ if (this_cpu_read(printk_context) || in_nmi())
+ return;
+
+ while (timeout_ms > 0) {
+ if (console_trylock()) {
+ console_unlock();
+ return;
+ }
+
+ udelay(1000);
+ timeout_ms -= 1;
+ }
+}
diff --git a/kernel/reboot.c b/kernel/reboot.c
index a091145ee710..b44165b1a399 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -82,6 +82,7 @@ void kernel_restart_prepare(char *cmd)
{
blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
system_state = SYSTEM_RESTART;
+ try_block_console_kthreads(10000);
usermodehelper_disable();
device_shutdown();
}
@@ -270,6 +271,7 @@ static void kernel_shutdown_prepare(enum system_states state)
blocking_notifier_call_chain(&reboot_notifier_list,
(state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
system_state = state;
+ try_block_console_kthreads(10000);
usermodehelper_disable();
device_shutdown();
}