Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking changes from Ingo Molnar:
 "The main changes in this cycle were:

   - pvqspinlock statistics fixes (Davidlohr Bueso)

   - flip atomic_fetch_or() arguments (Peter Zijlstra)

   - locktorture simplification (Paul E.  McKenney)

   - documentation updates (SeongJae Park, David Howells, Davidlohr
     Bueso, Paul E McKenney, Peter Zijlstra, Will Deacon)

   - various fixes"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/atomics: Flip atomic_fetch_or() arguments
  locking/pvqspinlock: Robustify init_qspinlock_stat()
  locking/pvqspinlock: Avoid double resetting of stats
  lcoking/locktorture: Simplify the torture_runnable computation
  locking/Documentation: Clarify that ACQUIRE applies to loads, RELEASE applies to stores
  locking/Documentation: State purpose of memory-barriers.txt
  locking/Documentation: Add disclaimer
  locking/Documentation/lockdep: Fix spelling mistakes
  locking/lockdep: Deinline register_lock_class(), save 2328 bytes
  locking/locktorture: Fix NULL pointer dereference for cleanup paths
  locking/locktorture: Fix deboosting NULL pointer dereference
  locking/Documentation: Mention smp_cond_acquire()
  locking/Documentation: Insert white spaces consistently
  locking/Documentation: Fix formatting inconsistencies
  locking/Documentation: Add missed subsection in TOC
  locking/Documentation: Fix missed s/lock/acquire renames
  locking/Documentation: Clarify relationship of barrier() to control dependencies

3 files changed, 31 insertions, 20 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 78c1c0ee6dc1..874d53eaf389 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -708,7 +708,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
  * yet. Otherwise we look it up. We cache the result in the lock object
  * itself, so actual lookup of the hash should be once per lock object.
  */
-static inline struct lock_class *
+static struct lock_class *
 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 {
         struct lockdep_subclass_key *key;
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 8ef1919d63b2..f8c5af52a131 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -75,12 +75,7 @@ struct lock_stress_stats {
         long n_lock_acquired;
 };
 
-#if defined(MODULE)
-#define LOCKTORTURE_RUNNABLE_INIT 1
-#else
-#define LOCKTORTURE_RUNNABLE_INIT 0
-#endif
-int torture_runnable = LOCKTORTURE_RUNNABLE_INIT;
+int torture_runnable = IS_ENABLED(MODULE);
 module_param(torture_runnable, int, 0444);
 MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init");
 
@@ -394,12 +389,12 @@ static void torture_rtmutex_boost(struct torture_random_state *trsp)
 
         if (!rt_task(current)) {
                 /*
-                 * (1) Boost priority once every ~50k operations. When the
+                 * Boost priority once every ~50k operations. When the
                  * task tries to take the lock, the rtmutex it will account
                  * for the new priority, and do any corresponding pi-dance.
                  */
-                if (!(torture_random(trsp) %
-                      (cxt.nrealwriters_stress * factor))) {
+                if (trsp && !(torture_random(trsp) %
+                              (cxt.nrealwriters_stress * factor))) {
                         policy = SCHED_FIFO;
                         param.sched_priority = MAX_RT_PRIO - 1;
                 } else /* common case, do nothing */
@@ -748,6 +743,15 @@ static void lock_torture_cleanup(void)
         if (torture_cleanup_begin())
                 return;
 
+        /*
+         * Indicates early cleanup, meaning that the test has not run,
+         * such as when passing bogus args when loading the module. As
+         * such, only perform the underlying torture-specific cleanups,
+         * and avoid anything related to locktorture.
+         */
+        if (!cxt.lwsa)
+                goto end;
+
         if (writer_tasks) {
                 for (i = 0; i < cxt.nrealwriters_stress; i++)
                         torture_stop_kthread(lock_torture_writer,
@@ -776,6 +780,7 @@ static void lock_torture_cleanup(void)
         else
                 lock_torture_print_module_parms(cxt.cur_ops,
                                                 "End of test: SUCCESS");
+end:
         torture_cleanup_end();
 }
 
@@ -870,6 +875,7 @@ static int __init lock_torture_init(void)
                         VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
                         firsterr = -ENOMEM;
                         kfree(cxt.lwsa);
+                        cxt.lwsa = NULL;
                         goto unwind;
                 }
 
@@ -878,6 +884,7 @@ static int __init lock_torture_init(void)
                         cxt.lrsa[i].n_lock_acquired = 0;
                 }
         }
+
         lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
 
         /* Prepare torture context. */
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index d734b7502001..22e025309845 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -191,8 +191,6 @@ static ssize_t qstat_write(struct file *file, const char __user *user_buf,
 
                 for (i = 0 ; i < qstat_num; i++)
                         WRITE_ONCE(ptr[i], 0);
-                for (i = 0 ; i < qstat_num; i++)
-                        WRITE_ONCE(ptr[i], 0);
         }
         return count;
 }
@@ -214,10 +212,8 @@ static int __init init_qspinlock_stat(void)
         struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL);
         int i;
 
-        if (!d_qstat) {
-                pr_warn("Could not create 'qlockstat' debugfs directory\n");
-                return 0;
-        }
+        if (!d_qstat)
+                goto out;
 
         /*
          * Create the debugfs files
@@ -227,12 +223,20 @@ static int __init init_qspinlock_stat(void)
          * performance.
          */
         for (i = 0; i < qstat_num; i++)
-                debugfs_create_file(qstat_names[i], 0400, d_qstat,
-                                   (void *)(long)i, &fops_qstat);
+                if (!debugfs_create_file(qstat_names[i], 0400, d_qstat,
+                                         (void *)(long)i, &fops_qstat))
+                        goto fail_undo;
+
+        if (!debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
+                                 (void *)(long)qstat_reset_cnts, &fops_qstat))
+                goto fail_undo;
 
-        debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
-                           (void *)(long)qstat_reset_cnts, &fops_qstat);
         return 0;
+fail_undo:
+        debugfs_remove_recursive(d_qstat);
+out:
+        pr_warn("Could not create 'qlockstat' debugfs entries\n");
+        return -ENOMEM;
 }
 fs_initcall(init_qspinlock_stat);