[05/54] tracing: Remove code which merges duplicates

Commit Message

[e-mail] Aug. 29, 2018, 12:17 p.m. UTC

We now have the logic to detect and remove duplicates in the
tracing_map hash table. The code which merges duplicates in the
histogram is redundant now. So, modify this code just to detect
duplicates. The duplication detection code is still kept to ensure
that any rare race condition which might cause duplicates does not go
unnoticed.

Link: http://lkml.kernel.org/r/552[e-mail]

Signed-off-by: Vedang Patel <[e-mail]>
Signed-off-by: Tom Zanussi <[e-mail]>
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>
(cherry picked from commit c193707dde77ace92a649cd59a17e105e2fbeaef)
Signed-off-by: Hirotaka MOTAI <[e-mail]>
---
 kernel/trace/trace_events_hist.c | 11 -----
 kernel/trace/tracing_map.c       | 83 +++-----------------------------
 kernel/trace/tracing_map.h       |  7 ---
 3 files changed, 6 insertions(+), 95 deletions(-)

Patch

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1e1558c9..712260e7 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -335,37 +335,26 @@  static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
 				return -ENOMEM;
 			break;
 		}
 	}
 
 	return 0;
 }
 
-static void hist_trigger_elt_comm_copy(struct tracing_map_elt *to,
-				       struct tracing_map_elt *from)
-{
-	char *comm_from = from->private_data;
-	char *comm_to = to->private_data;
-
-	if (comm_from)
-		memcpy(comm_to, comm_from, TASK_COMM_LEN + 1);
-}
-
 static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
 {
 	char *comm = elt->private_data;
 
 	if (comm)
 		save_comm(comm, current);
 }
 
 static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
 	.elt_alloc	= hist_trigger_elt_comm_alloc,
-	.elt_copy	= hist_trigger_elt_comm_copy,
 	.elt_free	= hist_trigger_elt_comm_free,
 	.elt_init	= hist_trigger_elt_comm_init,
 };
 
 static void destroy_hist_field(struct hist_field *hist_field,
 			       unsigned int level)
 {
 	unsigned int i;
diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index 305039b1..8d9feee5 100644
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -810,109 +810,41 @@  create_sort_entry(void *key, struct tracing_map_elt *elt)
 		return NULL;
 
 	sort_entry->key = key;
 	sort_entry->elt = elt;
 
 	return sort_entry;
 }
 
-static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
-{
-	struct tracing_map_elt *dup_elt;
-	unsigned int i;
-
-	dup_elt = tracing_map_elt_alloc(elt->map);
-	if (IS_ERR(dup_elt))
-		return NULL;
-
-	if (elt->map->ops && elt->map->ops->elt_copy)
-		elt->map->ops->elt_copy(dup_elt, elt);
-
-	dup_elt->private_data = elt->private_data;
-	memcpy(dup_elt->key, elt->key, elt->map->key_size);
-
-	for (i = 0; i < elt->map->n_fields; i++) {
-		atomic64_set(&dup_elt->fields[i].sum,
-			     atomic64_read(&elt->fields[i].sum));
-		dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
-	}
-
-	return dup_elt;
-}
-
-static int merge_dup(struct tracing_map_sort_entry **sort_entries,
-		     unsigned int target, unsigned int dup)
-{
-	struct tracing_map_elt *target_elt, *elt;
-	bool first_dup = (target - dup) == 1;
-	int i;
-
-	if (first_dup) {
-		elt = sort_entries[target]->elt;
-		target_elt = copy_elt(elt);
-		if (!target_elt)
-			return -ENOMEM;
-		sort_entries[target]->elt = target_elt;
-		sort_entries[target]->elt_copied = true;
-	} else
-		target_elt = sort_entries[target]->elt;
-
-	elt = sort_entries[dup]->elt;
-
-	for (i = 0; i < elt->map->n_fields; i++)
-		atomic64_add(atomic64_read(&elt->fields[i].sum),
-			     &target_elt->fields[i].sum);
-
-	sort_entries[dup]->dup = true;
-
-	return 0;
-}
-
-static int merge_dups(struct tracing_map_sort_entry **sort_entries,
+static void detect_dups(struct tracing_map_sort_entry **sort_entries,
 		      int n_entries, unsigned int key_size)
 {
 	unsigned int dups = 0, total_dups = 0;
-	int err, i, j;
+	int i;
 	void *key;
 
 	if (n_entries < 2)
-		return total_dups;
+		return;
 
 	sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
 	     (int (*)(const void *, const void *))cmp_entries_dup, NULL);
 
 	key = sort_entries[0]->key;
 	for (i = 1; i < n_entries; i++) {
 		if (!memcmp(sort_entries[i]->key, key, key_size)) {
 			dups++; total_dups++;
-			err = merge_dup(sort_entries, i - dups, i);
-			if (err)
-				return err;
 			continue;
 		}
 		key = sort_entries[i]->key;
 		dups = 0;
 	}
 
-	if (!total_dups)
-		return total_dups;
-
-	for (i = 0, j = 0; i < n_entries; i++) {
-		if (!sort_entries[i]->dup) {
-			sort_entries[j] = sort_entries[i];
-			if (j++ != i)
-				sort_entries[i] = NULL;
-		} else {
-			destroy_sort_entry(sort_entries[i]);
-			sort_entries[i] = NULL;
-		}
-	}
-
-	return total_dups;
+	WARN_ONCE(total_dups > 0,
+		  "Duplicates detected: %d\n", total_dups);
 }
 
 static bool is_key(struct tracing_map *map, unsigned int field_idx)
 {
 	unsigned int i;
 
 	for (i = 0; i < map->n_keys; i++)
 		if (map->key_idx[i] == field_idx)
@@ -1028,20 +960,17 @@  int tracing_map_sort_entries(struct tracing_map *map,
 		goto free;
 	}
 
 	if (n_entries == 1) {
 		*sort_entries = entries;
 		return 1;
 	}
 
-	ret = merge_dups(entries, n_entries, map->key_size);
-	if (ret < 0)
-		goto free;
-	n_entries -= ret;
+	detect_dups(entries, n_entries, map->key_size);
 
 	if (is_key(map, sort_keys[0].field_idx))
 		cmp_entries_fn = cmp_entries_key;
 	else
 		cmp_entries_fn = cmp_entries_sum;
 
 	set_sort_key(map, &sort_keys[0]);
 
diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h
index ab0ca773..0de50bbc 100644
--- a/kernel/trace/tracing_map.h
+++ b/kernel/trace/tracing_map.h
@@ -210,36 +210,29 @@  struct tracing_map {
  *
  * @elt_alloc: When a tracing_map_elt is allocated, this function, if
  *	defined, will be called and gives clients the opportunity to
  *	allocate additional data and attach it to the element
  *	(tracing_map_elt->private_data is meant for that purpose).
  *	Element allocation occurs before tracing begins, when the
  *	tracing_map_init() call is made by client code.
  *
- * @elt_copy: At certain points in the lifetime of an element, it may
- *	need to be copied.  The copy should include a copy of the
- *	client-allocated data, which can be copied into the 'to'
- *	element from the 'from' element.
- *
  * @elt_free: When a tracing_map_elt is freed, this function is called
  *	and allows client-allocated per-element data to be freed.
  *
  * @elt_clear: This callback allows per-element client-defined data to
  *	be cleared, if applicable.
  *
  * @elt_init: This callback allows per-element client-defined data to
  *	be initialized when used i.e. when the element is actually
  *	claimed by tracing_map_insert() in the context of the map
  *	insertion.
  */
 struct tracing_map_ops {
 	int			(*elt_alloc)(struct tracing_map_elt *elt);
-	void			(*elt_copy)(struct tracing_map_elt *to,
-					    struct tracing_map_elt *from);
 	void			(*elt_free)(struct tracing_map_elt *elt);
 	void			(*elt_clear)(struct tracing_map_elt *elt);
 	void			(*elt_init)(struct tracing_map_elt *elt);
 };
 
 extern struct tracing_map *
 tracing_map_create(unsigned int map_bits,
 		   unsigned int key_size,