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Diffstat (limited to 'kernel/printk.c')
-rw-r--r--kernel/printk.c24
1 files changed, 21 insertions, 3 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 35185392173f..37dff3429adb 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -782,7 +782,7 @@ static inline int can_use_console(unsigned int cpu)
static int console_trylock_for_printk(unsigned int cpu)
__releases(&logbuf_lock)
{
- int retval = 0;
+ int retval = 0, wake = 0;
if (console_trylock()) {
retval = 1;
@@ -795,12 +795,14 @@ static int console_trylock_for_printk(unsigned int cpu)
*/
if (!can_use_console(cpu)) {
console_locked = 0;
- up(&console_sem);
+ wake = 1;
retval = 0;
}
}
printk_cpu = UINT_MAX;
spin_unlock(&logbuf_lock);
+ if (wake)
+ up(&console_sem);
return retval;
}
static const char recursion_bug_msg [] =
@@ -1242,7 +1244,7 @@ void console_unlock(void)
{
unsigned long flags;
unsigned _con_start, _log_end;
- unsigned wake_klogd = 0;
+ unsigned wake_klogd = 0, retry = 0;
if (console_suspended) {
up(&console_sem);
@@ -1251,6 +1253,7 @@ void console_unlock(void)
console_may_schedule = 0;
+again:
for ( ; ; ) {
spin_lock_irqsave(&logbuf_lock, flags);
wake_klogd |= log_start - log_end;
@@ -1271,8 +1274,23 @@ void console_unlock(void)
if (unlikely(exclusive_console))
exclusive_console = NULL;
+ spin_unlock(&logbuf_lock);
+
up(&console_sem);
+
+ /*
+ * Someone could have filled up the buffer again, so re-check if there's
+ * something to flush. In case we cannot trylock the console_sem again,
+ * there's a new owner and the console_unlock() from them will do the
+ * flush, no worries.
+ */
+ spin_lock(&logbuf_lock);
+ if (con_start != log_end)
+ retry = 1;
spin_unlock_irqrestore(&logbuf_lock, flags);
+ if (retry && console_trylock())
+ goto again;
+
if (wake_klogd)
wake_up_klogd();
}