torture: Convert torture_shutdown() to hrtimer

Upcoming changes to the timer wheel introduce significant inaccuracy
and possibly also an ultimate limit on timeout duration.  This is a
problem for the current implementation of torture_shutdown() because
(1) shutdown times are user-specified, and can therefore be quite long,
and (2) the torture scripting will kill a test instance that runs for
more than a few minutes longer than scheduled.  This commit therefore
converts the torture_shutdown() timed waits to an hrtimer, thus avoiding
too-short torture test runs as well as death by scripting.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/kernel/torture.c b/kernel/torture.c
index 75961b3decfe9489cfa08459a8efba8931a0343a..0d887eb62856e38761aa840ab22347cdc98c1c90 100644 (file)
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -43,6 +43,7 @@
 #include <linux/stat.h>
 #include <linux/slab.h>
 #include <linux/trace_clock.h>
+#include <linux/ktime.h>
 #include <asm/byteorder.h>
 #include <linux/torture.h>
 
@@ -446,9 +447,8 @@ EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
  * Variables for auto-shutdown.  This allows "lights out" torture runs
  * to be fully scripted.
  */
-static int shutdown_secs;              /* desired test duration in seconds. */
 static struct task_struct *shutdown_task;
-static unsigned long shutdown_time;    /* jiffies to system shutdown. */
+static ktime_t shutdown_time;          /* time to system shutdown. */
 static void (*torture_shutdown_hook)(void);
 
 /*
@@ -471,20 +471,20 @@ EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
  */
 static int torture_shutdown(void *arg)
 {
-       long delta;
-       unsigned long jiffies_snap;
+       ktime_t ktime_snap;
 
        VERBOSE_TOROUT_STRING("torture_shutdown task started");
-       jiffies_snap = jiffies;
-       while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
+       ktime_snap = ktime_get();
+       while (ktime_before(ktime_snap, shutdown_time) &&
               !torture_must_stop()) {
-               delta = shutdown_time - jiffies_snap;
                if (verbose)
                        pr_alert("%s" TORTURE_FLAG
-                                "torture_shutdown task: %lu jiffies remaining\n",
-                                torture_type, delta);
-               schedule_timeout_interruptible(delta);
-               jiffies_snap = jiffies;
+                                "torture_shutdown task: %llu ms remaining\n",
+                                torture_type,
+                                ktime_ms_delta(shutdown_time, ktime_snap));
+               set_current_state(TASK_INTERRUPTIBLE);
+               schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
+               ktime_snap = ktime_get();
        }
        if (torture_must_stop()) {
                torture_kthread_stopping("torture_shutdown");
@@ -511,10 +511,9 @@ int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 {
        int ret = 0;
 
-       shutdown_secs = ssecs;
        torture_shutdown_hook = cleanup;
-       if (shutdown_secs > 0) {
-               shutdown_time = jiffies + shutdown_secs * HZ;
+       if (ssecs > 0) {
+               shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
                ret = torture_create_kthread(torture_shutdown, NULL,
                                             shutdown_task);
        }