[PATCH v5 09/15] locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count()

From: Bart Van Assche
Date: Mon Dec 17 2018 - 16:32:32 EST


This patch does not change any functionality but makes the next patch in
this series easier to read.

Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
kernel/locking/lockdep.c | 16 +++++++++++++++-
kernel/locking/lockdep_internals.h | 3 ++-
kernel/locking/lockdep_proc.c | 12 ++++++------
3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 287dc022d27a..a71ca42978c2 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2097,7 +2097,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
return 0;
}

-unsigned long nr_lock_chains;
+static unsigned long nr_lock_chains;
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
int nr_chain_hlocks;
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
@@ -2231,6 +2231,20 @@ static int check_no_collision(struct task_struct *curr,
return 1;
}

+/*
+ * Given an index that is >= -1, return the index of the next lock chain.
+ * Return -2 if there is no next lock chain.
+ */
+long lockdep_next_lockchain(long i)
+{
+ return i + 1 < nr_lock_chains ? i + 1 : -2;
+}
+
+unsigned long lock_chain_count(void)
+{
+ return nr_lock_chains;
+}
+
/*
* Adds a dependency chain into chain hashtable. And must be called with
* graph_lock held.
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 88c847a41c8a..ba8a4ac7bd04 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -96,7 +96,8 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);

extern unsigned long nr_lock_classes;
extern unsigned long nr_list_entries;
-extern unsigned long nr_lock_chains;
+long lockdep_next_lockchain(long i);
+unsigned long lock_chain_count(void);
extern int nr_chain_hlocks;
extern unsigned long nr_stack_trace_entries;

diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 3d31f9b0059e..9c49ec645d8b 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -104,18 +104,18 @@ static const struct seq_operations lockdep_ops = {
#ifdef CONFIG_PROVE_LOCKING
static void *lc_start(struct seq_file *m, loff_t *pos)
{
+ if (*pos < 0)
+ return NULL;
+
if (*pos == 0)
return SEQ_START_TOKEN;

- if (*pos - 1 < nr_lock_chains)
- return lock_chains + (*pos - 1);
-
- return NULL;
+ return lock_chains + (*pos - 1);
}

static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
{
- (*pos)++;
+ *pos = lockdep_next_lockchain(*pos - 1) + 1;
return lc_start(m, pos);
}

@@ -268,7 +268,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v)

#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
- nr_lock_chains, MAX_LOCKDEP_CHAINS);
+ lock_chain_count(), MAX_LOCKDEP_CHAINS);
seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
#endif
--
2.20.0.405.gbc1bbc6f85-goog