splat linux:shrinker: Fix fail-safe

Ensure the fail-safe is reset between successive tests.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/splat/splat-linux.c b/module/splat/splat-linux.c
index 6c89fc0345c1070783d44c1430505dbaf5ae6c3d..76e2398dabe63f0800c343a616ba1fe84a149996 100644 (file)
--- a/module/splat/splat-linux.c
+++ b/module/splat/splat-linux.c
@@ -101,6 +101,17 @@ static int
 __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc)
 {
        static int failsafe = 0;
+       static unsigned long last_splat_linux_shrinker_size = 0;
+
+       /*
+        * shrinker_size can only decrease or stay the same between callbacks
+        * in the same run, so Reset failsafe whenever shrinker increases
+        * as this indicates a new run.
+        */
+       if (last_splat_linux_shrinker_size < splat_linux_shrinker_size)
+               failsafe = 0;
+
+       last_splat_linux_shrinker_size = splat_linux_shrinker_size;
 
        if (sc->nr_to_scan) {
                splat_linux_shrinker_size = splat_linux_shrinker_size -
@@ -115,11 +126,17 @@ __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc)
        }
 
        /* Far more calls than expected abort drop_slab as a failsafe */
-       if ((++failsafe % 1000) == 0) {
+       if (failsafe > 100) {
                splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST3_NAME,
                    "Far more calls than expected (%d), size now %lu\n",
                   failsafe, splat_linux_shrinker_size);
                return -1;
+       } else {
+               /*
+                * We only increment failsafe if it doesn't trigger.  This
+                * makes any failsafe failure persistent until the next test.
+                */
+               failsafe++;
        }
 
        /* Shrinker has run, so signal back to test. */
@@ -180,7 +197,7 @@ splat_linux_test3(struct file *file, void *arg)
         */
        if (splat_linux_shrinker_size || splat_linux_shrinker_file) {
                splat_vprint(file, SPLAT_LINUX_TEST3_NAME,
-                   "Failed due to concurrent shrinker test, rc = %d\n", rc);
+                   "Failed due to concurrent shrinker test, rc = %d\n", rc);
                return (rc);
        }
 
@@ -202,7 +219,7 @@ splat_linux_test3(struct file *file, void *arg)
        rc = wait_event_timeout(shrinker_wait, !splat_linux_shrinker_size, HZ);
        if (!rc) {
                splat_vprint(file, SPLAT_LINUX_TEST3_NAME,
-                   "Failed cache shrinking timed out, size now %lu",
+                   "Failed cache shrinking timed out, size now %lu",
                    splat_linux_shrinker_size);
                rc = -ETIMEDOUT;
        } else {
@@ -211,7 +228,7 @@ splat_linux_test3(struct file *file, void *arg)
 
        if (!rc && splat_linux_shrinker_size != 0) {
                splat_vprint(file, SPLAT_LINUX_TEST3_NAME,
-                   "Failed cache was not shrunk to 0, size now %lu",
+                   "Failed cache was not shrunk to 0, size now %lu",
                    splat_linux_shrinker_size);
                rc = -EDOM;
        }