Release console_sem after unlocking the logbuf_lock so that we don't generate wakeups while holding logbuf_lock. This avoids some lock inversion troubles once we remove the lockdep_off bits between logbuf_lock and rq->lock (prints while holding rq->lock vs doing wakeups while holding logbuf_lock). There's of course still an actual deadlock where the printk()s under rq->lock will issue a wakeup from the up() call. Signed-off-by: Peter Zijlstra --- kernel/printk.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) Index: linux-2.6/kernel/printk.c =================================================================== --- linux-2.6.orig/kernel/printk.c +++ linux-2.6/kernel/printk.c @@ -782,7 +782,7 @@ static inline int can_use_console(unsign 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(un */ 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 [] = @@ -1271,8 +1273,8 @@ void console_unlock(void) if (unlikely(exclusive_console)) exclusive_console = NULL; - up(&console_sem); spin_unlock_irqrestore(&logbuf_lock, flags); + up(&console_sem); if (wake_klogd) wake_up_klogd(); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/