[PATCH v4 06/15] lockdep: Make save_trace can skip stack tracing of the current

Byungchul Park
2016-12-09T05:19:46Z

Currently, save_trace() always performs save_stack_trace() for the
current. However, crossrelease needs to use stack trace data of another
context instead of the current. So add a parameter for skipping stack
tracing of the current and make it use trace data, which is already
saved by crossrelease framework.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
kernel/locking/lockdep.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 3eaa11c..11580ec 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -387,15 +387,22 @@ static void print_lockdep_off(const char *bug_msg)
#endif
}

-static int save_trace(struct stack_trace *trace)
+static int save_trace(struct stack_trace *trace, int skip_tracing)
{
- trace->nr_entries = 0;
- trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
- trace->entries = stack_trace + nr_stack_trace_entries;
+ unsigned int nr_avail = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;

- trace->skip = 3;
-
- save_stack_trace(trace);
+ if (skip_tracing) {
+ trace->nr_entries = min(trace->nr_entries, nr_avail);
+ memcpy(stack_trace + nr_stack_trace_entries, trace->entries,
+ trace->nr_entries * sizeof(trace->entries[0]));
+ trace->entries = stack_trace + nr_stack_trace_entries;
+ } else {
+ trace->nr_entries = 0;
+ trace->max_entries = nr_avail;
+ trace->entries = stack_trace + nr_stack_trace_entries;
+ trace->skip = 3;
+ save_stack_trace(trace);
+ }

/*
* Some daft arches put -1 at the end to indicate its a full trace.
@@ -1172,7 +1179,7 @@ static noinline int print_circular_bug(struct lock_list *this,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;

- if (!save_trace(&this->trace))
+ if (!save_trace(&this->trace, 0))
return 0;

depth = get_lock_depth(target);
@@ -1518,13 +1525,13 @@ print_bad_irq_dependency(struct task_struct *curr,

printk("\nthe dependencies between %s-irq-safe lock", irqclass);
printk(" and the holding lock:\n");
- if (!save_trace(&prev_root->trace))
+ if (!save_trace(&prev_root->trace, 0))
return 0;
print_shortest_lock_dependencies(backwards_entry, prev_root);

printk("\nthe dependencies between the lock to be acquired");
printk(" and %s-irq-unsafe lock:\n", irqclass);
- if (!save_trace(&next_root->trace))
+ if (!save_trace(&next_root->trace, 0))
return 0;
print_shortest_lock_dependencies(forwards_entry, next_root);

@@ -1856,7 +1863,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
}

if (!own_trace && stack_saved && !*stack_saved) {
- if (!save_trace(&trace))
+ if (!save_trace(&trace, 0))
return 0;
*stack_saved = 1;
}
@@ -2547,7 +2554,7 @@ print_irq_inversion_bug(struct task_struct *curr,
lockdep_print_held_locks(curr);

printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
- if (!save_trace(&root->trace))
+ if (!save_trace(&root->trace, 0))
return 0;
print_shortest_lock_dependencies(other, root);

@@ -3134,7 +3141,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,

hlock_class(this)->usage_mask |= new_mask;

- if (!save_trace(hlock_class(this)->usage_traces + new_bit))
+ if (!save_trace(hlock_class(this)->usage_traces + new_bit, 0))
return 0;

switch (new_bit) {
--
1.9.1