1 files changed, 81 insertions, 7 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index b799a2ee96e..cbebc142be1 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -53,6 +53,10 @@ void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
 
 #define __LOG_BUF_LEN   (1 << CONFIG_LOG_BUF_SHIFT)
 
+#ifdef        CONFIG_DEBUG_LL
+extern void printascii(char *);
+#endif
+
 /* printk's without a loglevel use this.. */
 #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
 
@@ -297,6 +301,53 @@ static inline void boot_delay_msec(void)
 }
 #endif
 
+/*
+ * Return the number of unread characters in the log buffer.
+ */
+static int log_buf_get_len(void)
+{
+        return logged_chars;
+}
+
+/*
+ * Clears the ring-buffer
+ */
+void log_buf_clear(void)
+{
+        logged_chars = 0;
+}
+
+/*
+ * Copy a range of characters from the log buffer.
+ */
+int log_buf_copy(char *dest, int idx, int len)
+{
+        int ret, max;
+        bool took_lock = false;
+
+        if (!oops_in_progress) {
+                spin_lock_irq(&logbuf_lock);
+                took_lock = true;
+        }
+
+        max = log_buf_get_len();
+        if (idx < 0 || idx >= max) {
+                ret = -1;
+        } else {
+                if (len > max - idx)
+                        len = max - idx;
+                ret = len;
+                idx += (log_end - max);
+                while (len-- > 0)
+                        dest[len] = LOG_BUF(idx + len);
+        }
+
+        if (took_lock)
+                spin_unlock_irq(&logbuf_lock);
+
+        return ret;
+}
+
 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
 int dmesg_restrict = 1;
 #else
@@ -325,8 +376,10 @@ static int check_syslog_permissions(int type, bool from_file)
                         return 0;
                 /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
                 if (capable(CAP_SYS_ADMIN)) {
-                        WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN "
-                                 "but no CAP_SYSLOG (deprecated).\n");
+                        printk_once(KERN_WARNING "%s (%d): "
+                                 "Attempt to access syslog with CAP_SYS_ADMIN "
+                                 "but no CAP_SYSLOG (deprecated).\n",
+                                 current->comm, task_pid_nr(current));
                         return 0;
                 }
                 return -EPERM;
@@ -789,7 +842,7 @@ 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;
@@ -802,12 +855,14 @@ 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 [] =
@@ -882,6 +937,10 @@ asmlinkage int vprintk(const char *fmt, va_list args)
         if (trace_override && !trace_recurse)
                 TRACE("%s", printk_buf);
 
+#ifdef  CONFIG_DEBUG_LL
+        printascii(printk_buf);
+#endif
+
         p = printk_buf;
 
         /* Read log level and handle special printk prefix */
@@ -1156,7 +1215,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
         switch (action) {
         case CPU_ONLINE:
         case CPU_DEAD:
-        case CPU_DYING:
         case CPU_DOWN_FAILED:
         case CPU_UP_CANCELED:
                 console_lock();
@@ -1252,7 +1310,7 @@ 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);
@@ -1261,6 +1319,7 @@ void console_unlock(void)
 
         console_may_schedule = 0;
 
+again:
         for ( ; ; ) {
                 spin_lock_irqsave(&logbuf_lock, flags);
                 wake_klogd |= log_start - log_end;
@@ -1281,8 +1340,23 @@ 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();
 }
@@ -1594,7 +1668,7 @@ static int __init printk_late_init(void)
         struct console *con;
 
         for_each_console(con) {
-                if (con->flags & CON_BOOT) {
+                if (!keep_bootcon && con->flags & CON_BOOT) {
                         printk(KERN_INFO "turn off boot console %s%d\n",
                                 con->name, con->index);
                         unregister_console(con);