perf tools: Protect accesses the dso rbtrees/lists with a rw lock

To allow concurrent access, next step: refcount struct dso instances, so
that we can ditch unused them when the last map pointing to it goes
away.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/tip-yk1k08etpd2aoe3tnrf0oizn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 95 insertions, 47 deletions

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 5ec9e892c89b..ff0204ac4321 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -889,8 +889,8 @@ struct dso *machine__findnew_kernel(struct machine *machine, const char *name,
  * Either one of the dso or name parameter must be non-NULL or the
  * function will not work.
  */
-static struct dso *dso__findlink_by_longname(struct rb_root *root,
-                                             struct dso *dso, const char *name)
+static struct dso *__dso__findlink_by_longname(struct rb_root *root,
+                                               struct dso *dso, const char *name)
 {
         struct rb_node **p = &root->rb_node;
         struct rb_node  *parent = NULL;
@@ -937,10 +937,10 @@ static struct dso *dso__findlink_by_longname(struct rb_root *root,
         return NULL;
 }
 
-static inline struct dso *
-dso__find_by_longname(const struct rb_root *root, const char *name)
+static inline struct dso *__dso__find_by_longname(struct rb_root *root,
+                                                  const char *name)
 {
-        return dso__findlink_by_longname((struct rb_root *)root, NULL, name);
+        return __dso__findlink_by_longname(root, NULL, name);
 }
 
 void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated)
@@ -1149,14 +1149,20 @@ bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
         return have_build_id;
 }
 
-void dsos__add(struct dsos *dsos, struct dso *dso)
+void __dsos__add(struct dsos *dsos, struct dso *dso)
 {
         list_add_tail(&dso->node, &dsos->head);
-        dso__findlink_by_longname(&dsos->root, dso, NULL);
+        __dso__findlink_by_longname(&dsos->root, dso, NULL);
+}
+
+void dsos__add(struct dsos *dsos, struct dso *dso)
+{
+        pthread_rwlock_wrlock(&dsos->lock);
+        __dsos__add(dsos, dso);
+        pthread_rwlock_unlock(&dsos->lock);
 }
 
-struct dso *dsos__find(const struct dsos *dsos, const char *name,
-                       bool cmp_short)
+struct dso *__dsos__find(struct dsos *dsos, const char *name, bool cmp_short)
 {
         struct dso *pos;
 
@@ -1166,15 +1172,24 @@ struct dso *dsos__find(const struct dsos *dsos, const char *name,
                                 return pos;
                 return NULL;
         }
-        return dso__find_by_longname(&dsos->root, name);
+        return __dso__find_by_longname(&dsos->root, name);
 }
 
-struct dso *dsos__addnew(struct dsos *dsos, const char *name)
+struct dso *dsos__find(struct dsos *dsos, const char *name, bool cmp_short)
+{
+        struct dso *dso;
+        pthread_rwlock_rdlock(&dsos->lock);
+        dso = __dsos__find(dsos, name, cmp_short);
+        pthread_rwlock_unlock(&dsos->lock);
+        return dso;
+}
+
+struct dso *__dsos__addnew(struct dsos *dsos, const char *name)
 {
         struct dso *dso = dso__new(name);
 
         if (dso != NULL) {
-                dsos__add(dsos, dso);
+                __dsos__add(dsos, dso);
                 dso__set_basename(dso);
         }
         return dso;
@@ -1182,9 +1197,18 @@ struct dso *dsos__addnew(struct dsos *dsos, const char *name)
 
 struct dso *__dsos__findnew(struct dsos *dsos, const char *name)
 {
-        struct dso *dso = dsos__find(dsos, name, false);
+        struct dso *dso = __dsos__find(dsos, name, false);
+
+        return dso ? dso : __dsos__addnew(dsos, name);
+}
 
-        return dso ? dso : dsos__addnew(dsos, name);
+struct dso *dsos__findnew(struct dsos *dsos, const char *name)
+{
+        struct dso *dso;
+        pthread_rwlock_wrlock(&dsos->lock);
+        dso = __dsos__findnew(dsos, name);
+        pthread_rwlock_unlock(&dsos->lock);
+        return dso;
 }
 
 size_t __dsos__fprintf_buildid(struct list_head *head, FILE *fp,
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index ba2d90ed881f..c16ab5d849c3 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -4,6 +4,7 @@
 #include <linux/types.h>
 #include <linux/rbtree.h>
 #include <stdbool.h>
+#include <pthread.h>
 #include <linux/types.h>
 #include <linux/bitops.h>
 #include "map.h"
@@ -124,6 +125,7 @@ struct dso_cache {
 struct dsos {
         struct list_head head;
         struct rb_root   root;  /* rbtree root sorted by long name */
+        pthread_rwlock_t lock;
 };
 
 struct auxtrace_cache;
@@ -297,11 +299,13 @@ struct map *dso__new_map(const char *name);
 struct dso *machine__findnew_kernel(struct machine *machine, const char *name,
                                     const char *short_name, int dso_type);
 
+void __dsos__add(struct dsos *dsos, struct dso *dso);
 void dsos__add(struct dsos *dsos, struct dso *dso);
-struct dso *dsos__addnew(struct dsos *dsos, const char *name);
-struct dso *dsos__find(const struct dsos *dsos, const char *name,
-                       bool cmp_short);
+struct dso *__dsos__addnew(struct dsos *dsos, const char *name);
+struct dso *__dsos__find(struct dsos *dsos, const char *name, bool cmp_short);
+struct dso *dsos__find(struct dsos *dsos, const char *name, bool cmp_short);
 struct dso *__dsos__findnew(struct dsos *dsos, const char *name);
+struct dso *dsos__findnew(struct dsos *dsos, const char *name);
 bool __dsos__read_build_ids(struct list_head *head, bool with_hits);
 
 size_t __dsos__fprintf_buildid(struct list_head *head, FILE *fp,
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index dfd419797e6e..0cf56d6f073a 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -20,6 +20,7 @@ static void dsos__init(struct dsos *dsos)
 {
         INIT_LIST_HEAD(&dsos->head);
         dsos->root = RB_ROOT;
+        pthread_rwlock_init(&dsos->lock, NULL);
 }
 
 int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
@@ -81,15 +82,21 @@ out_delete:
         return NULL;
 }
 
-static void dsos__delete(struct dsos *dsos)
+static void dsos__exit(struct dsos *dsos)
 {
         struct dso *pos, *n;
 
+        pthread_rwlock_wrlock(&dsos->lock);
+
         list_for_each_entry_safe(pos, n, &dsos->head, node) {
                 RB_CLEAR_NODE(&pos->rb_node);
                 list_del(&pos->node);
                 dso__delete(pos);
         }
+
+        pthread_rwlock_unlock(&dsos->lock);
+
+        pthread_rwlock_destroy(&dsos->lock);
 }
 
 void machine__delete_threads(struct machine *machine)
@@ -110,7 +117,7 @@ void machine__delete_threads(struct machine *machine)
 void machine__exit(struct machine *machine)
 {
         map_groups__exit(&machine->kmaps);
-        dsos__delete(&machine->dsos);
+        dsos__exit(&machine->dsos);
         machine__exit_vdso(machine);
         zfree(&machine->root_dir);
         zfree(&machine->current_tid);
@@ -496,11 +503,13 @@ static struct dso *machine__findnew_module_dso(struct machine *machine,
 {
         struct dso *dso;
 
-        dso = dsos__find(&machine->dsos, m->name, true);
+        pthread_rwlock_wrlock(&machine->dsos.lock);
+
+        dso = __dsos__find(&machine->dsos, m->name, true);
         if (!dso) {
-                dso = dsos__addnew(&machine->dsos, m->name);
+                dso = __dsos__addnew(&machine->dsos, m->name);
                 if (dso == NULL)
-                        return NULL;
+                        goto out_unlock;
 
                 if (machine__is_host(machine))
                         dso->symtab_type = DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE;
@@ -515,6 +524,8 @@ static struct dso *machine__findnew_module_dso(struct machine *machine,
                 dso__set_long_name(dso, strdup(filename), true);
         }
 
+out_unlock:
+        pthread_rwlock_unlock(&machine->dsos.lock);
         return dso;
 }
 
@@ -1156,6 +1167,8 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
                 struct dso *kernel = NULL;
                 struct dso *dso;
 
+                pthread_rwlock_rdlock(&machine->dsos.lock);
+
                 list_for_each_entry(dso, &machine->dsos.head, node) {
 
                         /*
@@ -1184,6 +1197,8 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
                         break;
                 }
 
+                pthread_rwlock_unlock(&machine->dsos.lock);
+
                 if (kernel == NULL)
                         kernel = machine__findnew_dso(machine, kmmap_prefix);
                 if (kernel == NULL)
@@ -1948,5 +1963,5 @@ int machine__get_kernel_start(struct machine *machine)
 
 struct dso *machine__findnew_dso(struct machine *machine, const char *filename)
 {
-        return __dsos__findnew(&machine->dsos, filename);
+        return dsos__findnew(&machine->dsos, filename);
 }
diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
index 2e8f6886ca72..c646c74c34f8 100644
--- a/tools/perf/util/vdso.c
+++ b/tools/perf/util/vdso.c
@@ -120,14 +120,14 @@ void machine__exit_vdso(struct machine *machine)
         zfree(&machine->vdso_info);
 }
 
-static struct dso *machine__addnew_vdso(struct machine *machine, const char *short_name,
-                                        const char *long_name)
+static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
+                                          const char *long_name)
 {
         struct dso *dso;
 
         dso = dso__new(short_name);
         if (dso != NULL) {
-                dsos__add(&machine->dsos, dso);
+                __dsos__add(&machine->dsos, dso);
                 dso__set_long_name(dso, long_name, false);
         }
 
@@ -230,27 +230,31 @@ static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
         return vdso_file->temp_file_name;
 }
 
-static struct dso *vdso__findnew_compat(struct machine *machine,
-                                        struct vdso_file *vdso_file)
+static struct dso *__machine__findnew_compat(struct machine *machine,
+                                             struct vdso_file *vdso_file)
 {
         const char *file_name;
         struct dso *dso;
 
-        dso = dsos__find(&machine->dsos, vdso_file->dso_name, true);
+        pthread_rwlock_wrlock(&machine->dsos.lock);
+        dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
         if (dso)
-                return dso;
+                goto out_unlock;
 
         file_name = vdso__get_compat_file(vdso_file);
         if (!file_name)
-                return NULL;
+                goto out_unlock;
 
-        return machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
+        dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
+out_unlock:
+        pthread_rwlock_unlock(&machine->dsos.lock);
+        return dso;
 }
 
-static int machine__findnew_vdso_compat(struct machine *machine,
-                                    struct thread *thread,
-                                    struct vdso_info *vdso_info,
-                                    struct dso **dso)
+static int __machine__findnew_vdso_compat(struct machine *machine,
+                                          struct thread *thread,
+                                          struct vdso_info *vdso_info,
+                                          struct dso **dso)
 {
         enum dso_type dso_type;
 
@@ -267,10 +271,10 @@ static int machine__findnew_vdso_compat(struct machine *machine,
 
         switch (dso_type) {
         case DSO__TYPE_32BIT:
-                *dso = vdso__findnew_compat(machine, &vdso_info->vdso32);
+                *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
                 return 1;
         case DSO__TYPE_X32BIT:
-                *dso = vdso__findnew_compat(machine, &vdso_info->vdsox32);
+                *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
                 return 1;
         case DSO__TYPE_UNKNOWN:
         case DSO__TYPE_64BIT:
@@ -285,31 +289,32 @@ struct dso *machine__findnew_vdso(struct machine *machine,
                                   struct thread *thread __maybe_unused)
 {
         struct vdso_info *vdso_info;
-        struct dso *dso;
+        struct dso *dso = NULL;
 
+        pthread_rwlock_wrlock(&machine->dsos.lock);
         if (!machine->vdso_info)
                 machine->vdso_info = vdso_info__new();
 
         vdso_info = machine->vdso_info;
         if (!vdso_info)
-                return NULL;
+                goto out_unlock;
 
 #if BITS_PER_LONG == 64
-        if (machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
-                return dso;
+        if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
+                goto out_unlock;
 #endif
 
-        dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
+        dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
         if (!dso) {
                 char *file;
 
                 file = get_file(&vdso_info->vdso);
-                if (!file)
-                        return NULL;
-
-                dso = machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
+                if (file)
+                        dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
         }
 
+out_unlock:
+        pthread_rwlock_unlock(&machine->dsos.lock);
         return dso;
 }