1 files changed, 24 insertions, 2 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index e3602d0755b0..5052b5497c67 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -32,6 +32,7 @@
 #include <linux/security.h>
 #include <linux/bootmem.h>
 #include <linux/syscalls.h>
+#include <linux/kexec.h>
 
 #include <asm/uaccess.h>
 
@@ -135,6 +136,24 @@ static char *log_buf = __log_buf;
 static int log_buf_len = __LOG_BUF_LEN;
 static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
 
+#ifdef CONFIG_KEXEC
+/*
+ * This appends the listed symbols to /proc/vmcoreinfo
+ *
+ * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
+ * obtain access to symbols that are otherwise very difficult to locate.  These
+ * symbols are specifically used so that utilities can access and extract the
+ * dmesg log from a vmcore file after a crash.
+ */
+void log_buf_kexec_setup(void)
+{
+        VMCOREINFO_SYMBOL(log_buf);
+        VMCOREINFO_SYMBOL(log_end);
+        VMCOREINFO_SYMBOL(log_buf_len);
+        VMCOREINFO_SYMBOL(logged_chars);
+}
+#endif
+
 static int __init log_buf_len_setup(char *str)
 {
         unsigned size = memparse(str, &str);
@@ -1292,8 +1311,11 @@ EXPORT_SYMBOL(printk_ratelimit);
 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
                         unsigned int interval_msecs)
 {
-        if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) {
-                *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs);
+        if (*caller_jiffies == 0
+                        || !time_in_range(jiffies, *caller_jiffies,
+                                        *caller_jiffies
+                                        + msecs_to_jiffies(interval_msecs))) {
+                *caller_jiffies = jiffies;
                 return true;
         }
         return false;