summaryrefslogtreecommitdiff
path: root/kernel/locking/lockdep.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/locking/lockdep.c')
-rw-r--r--kernel/locking/lockdep.c56
1 files changed, 36 insertions, 20 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 66011c9f5df3..f73ca595b81e 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4629,7 +4629,7 @@ asmlinkage __visible void lockdep_sys_exit(void)
* the index to point to the last entry, which is already invalid.
*/
crossrelease_hist_end(XHLOCK_PROC);
- crossrelease_hist_start(XHLOCK_PROC);
+ crossrelease_hist_start(XHLOCK_PROC, false);
}
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
@@ -4725,25 +4725,25 @@ static inline void invalidate_xhlock(struct hist_lock *xhlock)
/*
* Lock history stacks; we have 3 nested lock history stacks:
*
- * Hard IRQ
- * Soft IRQ
- * History / Task
+ * HARD(IRQ)
+ * SOFT(IRQ)
+ * PROC(ess)
*
- * The thing is that once we complete a (Hard/Soft) IRQ the future task locks
- * should not depend on any of the locks observed while running the IRQ.
+ * The thing is that once we complete a HARD/SOFT IRQ the future task locks
+ * should not depend on any of the locks observed while running the IRQ. So
+ * what we do is rewind the history buffer and erase all our knowledge of that
+ * temporal event.
*
- * So what we do is rewind the history buffer and erase all our knowledge of
- * that temporal event.
- */
-
-/*
- * We need this to annotate lock history boundaries. Take for instance
- * workqueues; each work is independent of the last. The completion of a future
- * work does not depend on the completion of a past work (in general).
- * Therefore we must not carry that (lock) dependency across works.
+ * The PROCess one is special though; it is used to annotate independence
+ * inside a task.
+ *
+ * Take for instance workqueues; each work is independent of the last. The
+ * completion of a future work does not depend on the completion of a past work
+ * (in general). Therefore we must not carry that (lock) dependency across
+ * works.
*
* This is true for many things; pretty much all kthreads fall into this
- * pattern, where they have an 'idle' state and future completions do not
+ * pattern, where they have an invariant state and future completions do not
* depend on past completions. Its just that since they all have the 'same'
* form -- the kthread does the same over and over -- it doesn't typically
* matter.
@@ -4751,15 +4751,31 @@ static inline void invalidate_xhlock(struct hist_lock *xhlock)
* The same is true for system-calls, once a system call is completed (we've
* returned to userspace) the next system call does not depend on the lock
* history of the previous system call.
+ *
+ * They key property for independence, this invariant state, is that it must be
+ * a point where we hold no locks and have no history. Because if we were to
+ * hold locks, the restore at _end() would not necessarily recover it's history
+ * entry. Similarly, independence per-definition means it does not depend on
+ * prior state.
*/
-void crossrelease_hist_start(enum xhlock_context_t c)
+void crossrelease_hist_start(enum xhlock_context_t c, bool force)
{
struct task_struct *cur = current;
- if (cur->xhlocks) {
- cur->xhlock_idx_hist[c] = cur->xhlock_idx;
- cur->hist_id_save[c] = cur->hist_id;
+ if (!cur->xhlocks)
+ return;
+
+ /*
+ * We call this at an invariant point, no current state, no history.
+ */
+ if (c == XHLOCK_PROC) {
+ /* verified the former, ensure the latter */
+ WARN_ON_ONCE(!force && cur->lockdep_depth);
+ invalidate_xhlock(&xhlock(cur->xhlock_idx));
}
+
+ cur->xhlock_idx_hist[c] = cur->xhlock_idx;
+ cur->hist_id_save[c] = cur->hist_id;
}
void crossrelease_hist_end(enum xhlock_context_t c)