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Subject[tip:perf/urgent] perf symbols: Fix dso lookup by long name and missing buildids
Commit-ID:  e266a753bf51b2c3b46d0d230349662c35ac5629
Gitweb: http://git.kernel.org/tip/e266a753bf51b2c3b46d0d230349662c35ac5629
Author: Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Fri, 13 Nov 2015 11:48:30 +0200
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 13 Nov 2015 11:14:36 -0300

perf symbols: Fix dso lookup by long name and missing buildids

Commit 4598a0a6d22f ("perf symbols: Improve DSO long names lookup speed
with rbtree") Added a tree to lookup dsos by long name. That tree gets
corrupted whenever a dso long name is changed because the tree is not
updated.

One effect of that is buildid-list does not work with the 'with-hits'
option because dso lookup fails and results in two structs for the same
dso. The first has the buildid but no hits, the second has hits but no
buildid. e.g.

Before:

$ tools/perf/perf record ls
arch certs CREDITS Documentation firmware include
ipc Kconfig lib Makefile net REPORTING-BUGS
scripts sound usr block COPYING crypto
drivers fs init Kbuild kernel MAINTAINERS
mm README samples security tools virt
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.012 MB perf.data (11 samples) ]
$ tools/perf/perf buildid-list
574da826c66538a8d9060d393a8866289bd06005 [kernel.kallsyms]
30c94dc66a1fe95180c3d68d2b89e576d5ae213c /lib/x86_64-linux-gnu/libc-2.19.so
$ tools/perf/perf buildid-list -H
574da826c66538a8d9060d393a8866289bd06005 [kernel.kallsyms]
0000000000000000000000000000000000000000 /lib/x86_64-linux-gnu/libc-2.19.so

After:

$ tools/perf/perf buildid-list -H
574da826c66538a8d9060d393a8866289bd06005 [kernel.kallsyms]
30c94dc66a1fe95180c3d68d2b89e576d5ae213c /lib/x86_64-linux-gnu/libc-2.19.so

The fix is to record the root of the tree on the dso so that
dso__set_long_name() can update the tree when the long name changes.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Fixes: 4598a0a6d22f ("perf symbols: Improve DSO long names lookup speed with rbtree")
Link: http://lkml.kernel.org/r/1447408112-1920-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/dso.c | 17 +++++++++++++++++
tools/perf/util/dso.h | 1 +
tools/perf/util/machine.c | 1 +
3 files changed, 19 insertions(+)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 7c0c083..425df5c 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -933,6 +933,7 @@ static struct dso *__dso__findlink_by_longname(struct rb_root *root,
/* Add new node and rebalance tree */
rb_link_node(&dso->rb_node, parent, p);
rb_insert_color(&dso->rb_node, root);
+ dso->root = root;
}
return NULL;
}
@@ -945,15 +946,30 @@ static inline struct dso *__dso__find_by_longname(struct rb_root *root,

void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated)
{
+ struct rb_root *root = dso->root;
+
if (name == NULL)
return;

if (dso->long_name_allocated)
free((char *)dso->long_name);

+ if (root) {
+ rb_erase(&dso->rb_node, root);
+ /*
+ * __dso__findlink_by_longname() isn't guaranteed to add it
+ * back, so a clean removal is required here.
+ */
+ RB_CLEAR_NODE(&dso->rb_node);
+ dso->root = NULL;
+ }
+
dso->long_name = name;
dso->long_name_len = strlen(name);
dso->long_name_allocated = name_allocated;
+
+ if (root)
+ __dso__findlink_by_longname(root, dso, NULL);
}

void dso__set_short_name(struct dso *dso, const char *name, bool name_allocated)
@@ -1046,6 +1062,7 @@ struct dso *dso__new(const char *name)
dso->kernel = DSO_TYPE_USER;
dso->needs_swap = DSO_SWAP__UNSET;
RB_CLEAR_NODE(&dso->rb_node);
+ dso->root = NULL;
INIT_LIST_HEAD(&dso->node);
INIT_LIST_HEAD(&dso->data.open_entry);
pthread_mutex_init(&dso->lock, NULL);
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index fc8db9c..45ec4d0 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -135,6 +135,7 @@ struct dso {
pthread_mutex_t lock;
struct list_head node;
struct rb_node rb_node; /* rbtree node sorted by long name */
+ struct rb_root *root; /* root of rbtree that rb_node is in */
struct rb_root symbols[MAP__NR_TYPES];
struct rb_root symbol_names[MAP__NR_TYPES];
struct {
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 5ef90be..8b303ff 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -91,6 +91,7 @@ static void dsos__purge(struct dsos *dsos)

list_for_each_entry_safe(pos, n, &dsos->head, node) {
RB_CLEAR_NODE(&pos->rb_node);
+ pos->root = NULL;
list_del_init(&pos->node);
dso__put(pos);
}

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