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Patch "perf callchain: Reference count maps" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Mar 9, 2017

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This is a note to let you know that I've just added the patch titled

perf callchain: Reference count maps

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-callchain-reference-count-maps.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From aa33b9b9a2ebb00d33c83a5312d4fbf2d5aeba36 Mon Sep 17 00:00:00 2001

From: Krister Johansen <[email protected]>
Date: Thu, 5 Jan 2017 22:23:31 -0800
Subject: perf callchain: Reference count maps

From: Krister Johansen <[email protected]>

commit aa33b9b9a2ebb00d33c83a5312d4fbf2d5aeba36 upstream.

If dso__load_kcore frees all of the existing maps, but one has already been attached to a callchain cursor node, then we can get a SIGSEGV in any function that happens to try to use this invalid cursor. Use the existing map refcount mechanism to forestall cleanup of a map until the cursor iterates past the node.

Cc Frederic Weisbecker <[email protected]>
Cc Masami Hiramatsu <[email protected]>
Cc Namhyung Kim <[email protected]>
Fixes 84c2cafa2889 ("perf tools: Reference count struct map")
---
 tools/perf/util/callchain.c |   11 +++++++++--
 tools/perf/util/callchain.h |    6 ++++++
 tools/perf/util/hist.c      |    7 +++++++
 3 files changed, 22 insertions(+), 2 deletions(-)
tools/perf/util/callchain.c +9 -2
@@ -437,7 +437,7 @@ fill_node(struct callchain_node *node, s
 		}
 		call->ip = cursor_node->ip;
 		call->ms.sym = cursor_node->sym;
-		call->ms.map = cursor_node->map;
+		call->ms.map = map__get(cursor_node->map);
 		list_add_tail(&call->list, &node->val);
 
 		callchain_cursor_advance(cursor);
@@ -462,6 +462,7 @@ add_child(struct callchain_node *parent,
 
 		list_for_each_entry_safe(call, tmp, &new->val, list) {
 			list_del(&call->list);
+			map__zput(call->ms.map);
 			free(call);
 		}
 		free(new);
@@ -730,6 +731,7 @@ merge_chain_branch(struct callchain_curs
 		callchain_cursor_append(cursor, list->ip,
 					list->ms.map, list->ms.sym);
 		list_del(&list->list);
+		map__zput(list->ms.map);
 		free(list);
 	}
 
@@ -778,7 +780,8 @@ int callchain_cursor_append(struct callc
 	}
 
 	node->ip = ip;
-	node->map = map;
+	map__zput(node->map);
+	node->map = map__get(map);
 	node->sym = sym;
 
 	cursor->nr++;
@@ -945,11 +948,13 @@ static void free_callchain_node(struct c
 
 	list_for_each_entry_safe(list, tmp, &node->parent_val, list) {
 		list_del(&list->list);
+		map__zput(list->ms.map);
 		free(list);
 	}
 
 	list_for_each_entry_safe(list, tmp, &node->val, list) {
 		list_del(&list->list);
+		map__zput(list->ms.map);
 		free(list);
 	}
 
@@ -1013,6 +1018,7 @@ int callchain_node__make_parent_list(str
 				goto out;
 			*new = *chain;
 			new->has_children = false;
+			map__get(new->ms.map);
 			list_add_tail(&new->list, &head);
 		}
 		parent = parent->parent;
@@ -1033,6 +1039,7 @@ int callchain_node__make_parent_list(str
 out:
 	list_for_each_entry_safe(chain, new, &head, list) {
 		list_del(&chain->list);
+		map__zput(chain->ms.map);
 		free(chain);
 	}
 	return -ENOMEM;
tools/perf/util/callchain.h +6 -0
@@ -5,6 +5,7 @@
 #include <linux/list.h>
 #include <linux/rbtree.h>
 #include "event.h"
+#include "map.h"
 #include "symbol.h"
 
 #define HELP_PAD "\t\t\t\t"
@@ -174,8 +175,13 @@ int callchain_merge(struct callchain_cur
  */
 static inline void callchain_cursor_reset(struct callchain_cursor *cursor)
 {
+	struct callchain_cursor_node *node;
+
 	cursor->nr = 0;
 	cursor->last = &cursor->first;
+
+	for (node = cursor->first; node != NULL; node = node->next)
+		map__zput(node->map);
 }
 
 int callchain_cursor_append(struct callchain_cursor *cursor, u64 ip,
tools/perf/util/hist.c +7 -0
@@ -1,6 +1,7 @@
 #include "util.h"
 #include "build-id.h"
 #include "hist.h"
+#include "map.h"
 #include "session.h"
 #include "sort.h"
 #include "evlist.h"
@@ -1019,6 +1020,10 @@ int hist_entry_iter__add(struct hist_ent
 			 int max_stack_depth, void *arg)
 {
 	int err, err2;
+	struct map *alm = NULL;
+
+	if (al && al->map)
+		alm = map__get(al->map);
 
 	err = sample__resolve_callchain(iter->sample, &callchain_cursor, &iter->parent,
 					iter->evsel, al, max_stack_depth);
@@ -1058,6 +1063,8 @@ out:
 	if (!err)
 		err = err2;
 
+	map__put(alm);
+
 	return err;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/perf-callchain-reference-count-maps.patch