trace: Use 64-bit timekeeping

The ring_buffer_producer uses 'struct timeval' to measure
its start and end times. 'struct timeval' on 32-bit systems
will have its tv_sec value overflow in year 2038 and beyond.
This patch replaces struct timeval with 'ktime_t' which uses
64-bit representation for nanoseconds.

Link: http://lkml.kernel.org/r/20150128141611.GA2701@tinar

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 8 insertions, 10 deletions

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 3f9e328c30b5..13d945c0d03f 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -7,7 +7,7 @@
 #include <linux/completion.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
-#include <linux/time.h>
+#include <linux/ktime.h>
 #include <asm/local.h>
 
 struct rb_page {
@@ -17,7 +17,7 @@ struct rb_page {
 };
 
 /* run time and sleep time in seconds */
-#define RUN_TIME        10
+#define RUN_TIME        10ULL
 #define SLEEP_TIME      10
 
 /* number of events for writer to wake up the reader */
@@ -212,8 +212,7 @@ static void ring_buffer_consumer(void)
 
 static void ring_buffer_producer(void)
 {
-        struct timeval start_tv;
-        struct timeval end_tv;
+        ktime_t start_time, end_time, timeout;
         unsigned long long time;
         unsigned long long entries;
         unsigned long long overruns;
@@ -227,7 +226,8 @@ static void ring_buffer_producer(void)
          * make the system stall)
          */
         trace_printk("Starting ring buffer hammer\n");
-        do_gettimeofday(&start_tv);
+        start_time = ktime_get();
+        timeout = ktime_add_ns(start_time, RUN_TIME * NSEC_PER_SEC);
         do {
                 struct ring_buffer_event *event;
                 int *entry;
@@ -244,7 +244,7 @@ static void ring_buffer_producer(void)
                                 ring_buffer_unlock_commit(buffer, event);
                         }
                 }
-                do_gettimeofday(&end_tv);
+                end_time = ktime_get();
 
                 cnt++;
                 if (consumer && !(cnt % wakeup_interval))
@@ -264,7 +264,7 @@ static void ring_buffer_producer(void)
                         cond_resched();
 #endif
 
-        } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
+        } while (ktime_before(end_time, timeout) && !kill_test);
         trace_printk("End ring buffer hammer\n");
 
         if (consumer) {
@@ -280,9 +280,7 @@ static void ring_buffer_producer(void)
                 wait_for_completion(&read_done);
         }
 
-        time = end_tv.tv_sec - start_tv.tv_sec;
-        time *= USEC_PER_SEC;
-        time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
+        time = ktime_us_delta(end_time, start_time);
 
         entries = ring_buffer_entries(buffer);
         overruns = ring_buffer_overruns(buffer);