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-rw-r--r--drivers/tty/sysrq.c6
-rw-r--r--include/linux/printk.h2
-rw-r--r--kernel/panic.c3
-rw-r--r--kernel/printk/printk.c10
4 files changed, 21 insertions, 0 deletions
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 59e82e6d776d..573b2055173c 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -527,8 +527,12 @@ void __handle_sysrq(int key, bool check_mask)
{
struct sysrq_key_op *op_p;
int orig_log_level;
+ int orig_suppress_printk;
int i;
+ orig_suppress_printk = suppress_printk;
+ suppress_printk = 0;
+
rcu_sysrq_start();
rcu_read_lock();
/*
@@ -574,6 +578,8 @@ void __handle_sysrq(int key, bool check_mask)
}
rcu_read_unlock();
rcu_sysrq_end();
+
+ suppress_printk = orig_suppress_printk;
}
void handle_sysrq(int key)
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 84ea4d094af3..cefd374c47b1 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -82,6 +82,8 @@ static inline void console_verbose(void)
extern char devkmsg_log_str[];
struct ctl_table;
+extern int suppress_printk;
+
struct va_format {
const char *fmt;
va_list *va;
diff --git a/kernel/panic.c b/kernel/panic.c
index c1fcaad337b7..a6145050a8da 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -321,6 +321,9 @@ void panic(const char *fmt, ...)
disabled_wait();
#endif
pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
+
+ /* Do not scroll important messages printed above */
+ suppress_printk = 1;
local_irq_enable();
for (i = 0; ; i += PANIC_TIMER_STEP) {
touch_softlockup_watchdog();
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 02ca827b8fac..17102fd4c136 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -86,6 +86,12 @@ static DEFINE_SEMAPHORE(console_sem);
struct console *console_drivers;
EXPORT_SYMBOL_GPL(console_drivers);
+/*
+ * System may need to suppress printk message under certain
+ * circumstances, like after kernel panic happens.
+ */
+int __read_mostly suppress_printk;
+
#ifdef CONFIG_LOCKDEP
static struct lockdep_map console_lock_dep_map = {
.name = "console_lock"
@@ -1943,6 +1949,10 @@ asmlinkage int vprintk_emit(int facility, int level,
unsigned long flags;
u64 curr_log_seq;
+ /* Suppress unimportant messages after panic happens */
+ if (unlikely(suppress_printk))
+ return 0;
+
if (level == LOGLEVEL_SCHED) {
level = LOGLEVEL_DEFAULT;
in_sched = true;