Merge branch 'paul' (Fixups from Paul Gortmaker)

[linux-flexiantxendom0-3.2.10.git] / kernel / printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
index cb8a6bd..b663c2c 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -707,6 +707,9 @@ static bool printk_time = 0;
 #endif
 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
 
+static bool always_kmsg_dump;
+module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
+
 /* Check if we have any console registered that can be called early in boot. */
 static int have_callable_console(void)
 {
@@ -1213,13 +1216,27 @@ int is_console_locked(void)
        return console_locked;
 }
 
+/*
+ * Delayed printk facility, for scheduler-internal messages:
+ */
+#define PRINTK_BUF_SIZE                512
+
+#define PRINTK_PENDING_WAKEUP  0x01
+#define PRINTK_PENDING_SCHED   0x02
+
 static DEFINE_PER_CPU(int, printk_pending);
+static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
 
 void printk_tick(void)
 {
        if (__this_cpu_read(printk_pending)) {
-               __this_cpu_write(printk_pending, 0);
-               wake_up_interruptible(&log_wait);
+               int pending = __this_cpu_xchg(printk_pending, 0);
+               if (pending & PRINTK_PENDING_SCHED) {
+                       char *buf = __get_cpu_var(printk_sched_buf);
+                       printk(KERN_WARNING "[sched_delayed] %s", buf);
+               }
+               if (pending & PRINTK_PENDING_WAKEUP)
+                       wake_up_interruptible(&log_wait);
        }
 }
 
@@ -1233,7 +1250,7 @@ int printk_needs_cpu(int cpu)
 void wake_up_klogd(void)
 {
        if (waitqueue_active(&log_wait))
-               this_cpu_write(printk_pending, 1);
+               this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
 }
 
 /**
@@ -1626,6 +1643,26 @@ late_initcall(printk_late_init);
 
 #if defined CONFIG_PRINTK
 
+int printk_sched(const char *fmt, ...)
+{
+       unsigned long flags;
+       va_list args;
+       char *buf;
+       int r;
+
+       local_irq_save(flags);
+       buf = __get_cpu_var(printk_sched_buf);
+
+       va_start(args, fmt);
+       r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+       va_end(args);
+
+       __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+       local_irq_restore(flags);
+
+       return r;
+}
+
 /*
  * printk rate limiting, lifted from the networking subsystem.
  *
@@ -1737,6 +1774,9 @@ void kmsg_dump(enum kmsg_dump_reason reason)
        unsigned long l1, l2;
        unsigned long flags;
 
+       if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
+               return;
+
        /* Theoretically, the log could move on after we do this, but
           there's not a lot we can do about that. The new messages
           will overwrite the start of what we dump. */