Merge branch 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

* 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion
  printk: Fix console_sem vs logbuf_lock unlock race
  printk: Release console_sem after logbuf_lock

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 628276d..3956f51 100644 (file)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2481,15 +2481,10 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
 /*
  * Hardirqs will be enabled:
  */
-void trace_hardirqs_on_caller(unsigned long ip)
+static void __trace_hardirqs_on_caller(unsigned long ip)
 {
        struct task_struct *curr = current;
 
-       time_hardirqs_on(CALLER_ADDR0, ip);
-
-       if (unlikely(!debug_locks || current->lockdep_recursion))
-               return;
-
        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
                return;
 
@@ -2505,8 +2500,6 @@ void trace_hardirqs_on_caller(unsigned long ip)
        /* we'll do an OFF -> ON transition: */
        curr->hardirqs_enabled = 1;
 
-       if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
-               return;
        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
                return;
        /*
@@ -2528,6 +2521,21 @@ void trace_hardirqs_on_caller(unsigned long ip)
        curr->hardirq_enable_event = ++curr->irq_events;
        debug_atomic_inc(hardirqs_on_events);
 }
+
+void trace_hardirqs_on_caller(unsigned long ip)
+{
+       time_hardirqs_on(CALLER_ADDR0, ip);
+
+       if (unlikely(!debug_locks || current->lockdep_recursion))
+               return;
+
+       if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+               return;
+
+       current->lockdep_recursion = 1;
+       __trace_hardirqs_on_caller(ip);
+       current->lockdep_recursion = 0;
+}
 EXPORT_SYMBOL(trace_hardirqs_on_caller);
 
 void trace_hardirqs_on(void)
@@ -2577,7 +2585,7 @@ void trace_softirqs_on(unsigned long ip)
 {
        struct task_struct *curr = current;
 
-       if (unlikely(!debug_locks))
+       if (unlikely(!debug_locks || current->lockdep_recursion))
                return;
 
        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
@@ -2588,6 +2596,7 @@ void trace_softirqs_on(unsigned long ip)
                return;
        }
 
+       current->lockdep_recursion = 1;
        /*
         * We'll do an OFF -> ON transition:
         */
@@ -2602,6 +2611,7 @@ void trace_softirqs_on(unsigned long ip)
         */
        if (curr->hardirqs_enabled)
                mark_held_locks(curr, SOFTIRQ);
+       current->lockdep_recursion = 0;
 }
 
 /*
@@ -2611,7 +2621,7 @@ void trace_softirqs_off(unsigned long ip)
 {
        struct task_struct *curr = current;
 
-       if (unlikely(!debug_locks))
+       if (unlikely(!debug_locks || current->lockdep_recursion))
                return;
 
        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

diff --git a/kernel/printk.c b/kernel/printk.c
index 3518539..37dff34 100644 (file)
--- 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();
 }