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

Pull locking fixes from Ingo Molnar:
 "Three fixes:

    - Fix an rwsem spin-on-owner crash, introduced in v5.4

    - Fix a lockdep bug when running out of stack_trace entries,
      introduced in v5.4

    - Docbook fix"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Fix kernel crash when spinning on RWSEM_OWNER_UNKNOWN
  futex: Fix kernel-doc notation warning
  locking/lockdep: Fix buffer overrun problem in stack_trace[]

diff --git a/kernel/futex.c b/kernel/futex.c
index 03c518e..0cf84c8 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1178,6 +1178,7 @@ out_error:
 
 /**
  * wait_for_owner_exiting - Block until the owner has exited
+ * @ret: owner's current futex lock status
  * @exiting:   Pointer to the exiting task
  *
  * Caller must hold a refcount on @exiting.

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 32282e7..32406ef 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -482,7 +482,7 @@ static struct lock_trace *save_trace(void)
        struct lock_trace *trace, *t2;
        struct hlist_head *hash_head;
        u32 hash;
-       unsigned int max_entries;
+       int max_entries;
 
        BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
        BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
@@ -490,10 +490,8 @@ static struct lock_trace *save_trace(void)
        trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
        max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
                LOCK_TRACE_SIZE_IN_LONGS;
-       trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
 
-       if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
-           LOCK_TRACE_SIZE_IN_LONGS - 1) {
+       if (max_entries <= 0) {
                if (!debug_locks_off_graph_unlock())
                        return NULL;
 
@@ -502,6 +500,7 @@ static struct lock_trace *save_trace(void)
 
                return NULL;
        }
+       trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
 
        hash = jhash(trace->entries, trace->nr_entries *
                     sizeof(trace->entries[0]), 0);

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 44e6876..0d9b6be 100644 (file)
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1226,8 +1226,8 @@ wait:
                 * In this case, we attempt to acquire the lock again
                 * without sleeping.
                 */
-               if ((wstate == WRITER_HANDOFF) &&
-                   (rwsem_spin_on_owner(sem, 0) == OWNER_NULL))
+               if (wstate == WRITER_HANDOFF &&
+                   rwsem_spin_on_owner(sem, RWSEM_NONSPINNABLE) == OWNER_NULL)
                        goto trylock_again;
 
                /* Block until there are no active lockers. */