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Subject[RFC patch 31/41] dm persistent data: Simplify stack trace handling
Replace the indirection through struct stack_trace with an invocation of
the storage array based interface. This results in less storage space and
indirection.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
---
drivers/md/persistent-data/dm-block-manager.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -35,7 +35,10 @@
#define MAX_HOLDERS 4
#define MAX_STACK 10

-typedef unsigned long stack_entries[MAX_STACK];
+struct stack_store {
+ unsigned int nr_entries;
+ unsigned long entries[MAX_STACK];
+};

struct block_lock {
spinlock_t lock;
@@ -44,8 +47,7 @@ struct block_lock {
struct task_struct *holders[MAX_HOLDERS];

#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
- struct stack_trace traces[MAX_HOLDERS];
- stack_entries entries[MAX_HOLDERS];
+ struct stack_store traces[MAX_HOLDERS];
#endif
};

@@ -73,7 +75,7 @@ static void __add_holder(struct block_lo
{
unsigned h = __find_holder(lock, NULL);
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
- struct stack_trace *t;
+ struct stack_store *t;
#endif

get_task_struct(task);
@@ -81,11 +83,7 @@ static void __add_holder(struct block_lo

#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
t = lock->traces + h;
- t->nr_entries = 0;
- t->max_entries = MAX_STACK;
- t->entries = lock->entries[h];
- t->skip = 2;
- save_stack_trace(t);
+ t->nr_entries = stack_trace_save(t->entries, MAX_STACK, 2);
#endif
}

@@ -106,7 +104,8 @@ static int __check_holder(struct block_l
DMERR("recursive lock detected in metadata");
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
DMERR("previously held here:");
- print_stack_trace(lock->traces + i, 4);
+ stack_trace_print(lock->traces[i].entries,
+ lock->traces[i].nr_entries, 4);

DMERR("subsequent acquisition attempted here:");
dump_stack();

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