Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android

[firefly-linux-kernel-4.4.55.git] / kernel / printk / printk.c

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2ce8826f1053d801f0b003f5a3e67de0fdfe8e30..e7e586bb20224d73d782ecac1048402300b98968 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -55,6 +55,10 @@
 #include "console_cmdline.h"
 #include "braille.h"
 
+#ifdef CONFIG_EARLY_PRINTK_DIRECT
+extern void printascii(char *);
+#endif
+
 int console_printk[4] = {
        CONSOLE_LOGLEVEL_DEFAULT,       /* console_loglevel */
        MESSAGE_LOGLEVEL_DEFAULT,       /* default_message_loglevel */
@@ -1754,6 +1758,10 @@ asmlinkage int vprintk_emit(int facility, int level,
                }
        }
 
+#ifdef CONFIG_EARLY_PRINTK_DIRECT
+       printascii(text);
+#endif
+
        if (level == LOGLEVEL_DEFAULT)
                level = default_message_loglevel;
 
@@ -2233,13 +2241,24 @@ void console_unlock(void)
        static u64 seen_seq;
        unsigned long flags;
        bool wake_klogd = false;
-       bool retry;
+       bool do_cond_resched, retry;
 
        if (console_suspended) {
                up_console_sem();
                return;
        }
 
+       /*
+        * Console drivers are called under logbuf_lock, so
+        * @console_may_schedule should be cleared before; however, we may
+        * end up dumping a lot of lines, for example, if called from
+        * console registration path, and should invoke cond_resched()
+        * between lines if allowable.  Not doing so can cause a very long
+        * scheduling stall on a slow console leading to RCU stall and
+        * softlockup warnings which exacerbate the issue with more
+        * messages practically incapacitating the system.
+        */
+       do_cond_resched = console_may_schedule;
        console_may_schedule = 0;
 
        /* flush buffered message fragment immediately to console */
@@ -2311,6 +2330,9 @@ skip:
                call_console_drivers(level, ext_text, ext_len, text, len);
                start_critical_timings();
                local_irq_restore(flags);
+
+               if (do_cond_resched)
+                       cond_resched();
        }
        console_locked = 0;
 
@@ -2378,6 +2400,25 @@ void console_unblank(void)
        console_unlock();
 }
 
+/**
+ * console_flush_on_panic - flush console content on panic
+ *
+ * Immediately output all pending messages no matter what.
+ */
+void console_flush_on_panic(void)
+{
+       /*
+        * If someone else is holding the console lock, trylock will fail
+        * and may_schedule may be set.  Ignore and proceed to unlock so
+        * that messages are flushed out.  As this can be called from any
+        * context and we don't want to get preempted while flushing,
+        * ensure may_schedule is cleared.
+        */
+       console_trylock();
+       console_may_schedule = 0;
+       console_unlock();
+}
+
 /*
  * Return the console tty driver structure and its associated index
  */