diff mbox series

[v5,16/50] perf maps: Add remove maps function to remove a map based on callback

Message ID 20231127220902.1315692-17-irogers@google.com
State New
Headers
Series Improvements to memory use |

Commit Message

Ian Rogers Nov. 27, 2023, 10:08 p.m. UTC 
  Removing maps wasn't being done under the write lock. Similar to
maps__for_each_map, iterate the entries but in this case remove the
entry based on the result of the callback. If an entry was removed
then maps_by_name also needs updating, so add missed flush.

In dso__load_kcore, the test of map to save would always be false with
REFCNT_CHECKING because of a missing RC_CHK_ACCESS.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/maps.c   | 24 ++++++++++++++++++++++++
 tools/perf/util/maps.h   |  6 ++----
 tools/perf/util/symbol.c | 24 ++++++++++++------------
 3 files changed, 38 insertions(+), 16 deletions(-)

Comments

Namhyung Kim Dec. 4, 2023, 11:49 p.m. UTC | #1 
On Mon, Nov 27, 2023 at 2:10 PM Ian Rogers <irogers@google.com> wrote:
>
> Removing maps wasn't being done under the write lock. Similar to
> maps__for_each_map, iterate the entries but in this case remove the
> entry based on the result of the callback. If an entry was removed
> then maps_by_name also needs updating, so add missed flush.
>
> In dso__load_kcore, the test of map to save would always be false with
> REFCNT_CHECKING because of a missing RC_CHK_ACCESS.
>
> Signed-off-by: Ian Rogers <irogers@google.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

A nitpick below,

> ---
[SNIP]
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 72f03b875478..30da8a405d11 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -1239,13 +1239,23 @@ static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
>         return 0;
>  }
>
> +static bool remove_old_maps(struct map *map, void *data)
> +{
> +       const struct map *map_to_save = data;
> +
> +       /*
> +        * We need to preserve eBPF maps even if they are covered by kcore,
> +        * because we need to access eBPF dso for source data.
> +        */
> +       return RC_CHK_ACCESS(map) != RC_CHK_ACCESS(map_to_save) && !__map__is_bpf_prog(map);

RC_CHK_EQUAL(map, map_to_save) ?

Thanks,
Namhyung


> +}
> +
>  static int dso__load_kcore(struct dso *dso, struct map *map,
>                            const char *kallsyms_filename)
>  {
>         struct maps *kmaps = map__kmaps(map);
>         struct kcore_mapfn_data md;
>         struct map *replacement_map = NULL;
> -       struct map_rb_node *old_node, *next;
>         struct machine *machine;
>         bool is_64_bit;
>         int err, fd;
> @@ -1292,17 +1302,7 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
>         }
>
>         /* Remove old maps */
> -       maps__for_each_entry_safe(kmaps, old_node, next) {
> -               struct map *old_map = old_node->map;
> -
> -               /*
> -                * We need to preserve eBPF maps even if they are
> -                * covered by kcore, because we need to access
> -                * eBPF dso for source data.
> -                */
> -               if (old_map != map && !__map__is_bpf_prog(old_map))
> -                       maps__remove(kmaps, old_map);
> -       }
> +       maps__remove_maps(kmaps, remove_old_maps, map);
>         machine->trampolines_mapped = false;
>
>         /* Find the kernel map using the '_stext' symbol */
> --
> 2.43.0.rc1.413.gea7ed67945-goog
>
Ian Rogers Dec. 6, 2023, 11:28 p.m. UTC | #2 
On Mon, Dec 4, 2023 at 3:50 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Mon, Nov 27, 2023 at 2:10 PM Ian Rogers <irogers@google.com> wrote:
> >
> > Removing maps wasn't being done under the write lock. Similar to
> > maps__for_each_map, iterate the entries but in this case remove the
> > entry based on the result of the callback. If an entry was removed
> > then maps_by_name also needs updating, so add missed flush.
> >
> > In dso__load_kcore, the test of map to save would always be false with
> > REFCNT_CHECKING because of a missing RC_CHK_ACCESS.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
>
> Acked-by: Namhyung Kim <namhyung@kernel.org>
>
> A nitpick below,
>
> > ---
> [SNIP]
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index 72f03b875478..30da8a405d11 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -1239,13 +1239,23 @@ static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
> >         return 0;
> >  }
> >
> > +static bool remove_old_maps(struct map *map, void *data)
> > +{
> > +       const struct map *map_to_save = data;
> > +
> > +       /*
> > +        * We need to preserve eBPF maps even if they are covered by kcore,
> > +        * because we need to access eBPF dso for source data.
> > +        */
> > +       return RC_CHK_ACCESS(map) != RC_CHK_ACCESS(map_to_save) && !__map__is_bpf_prog(map);
>
> RC_CHK_EQUAL(map, map_to_save) ?

Done in v6.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > +}
> > +
> >  static int dso__load_kcore(struct dso *dso, struct map *map,
> >                            const char *kallsyms_filename)
> >  {
> >         struct maps *kmaps = map__kmaps(map);
> >         struct kcore_mapfn_data md;
> >         struct map *replacement_map = NULL;
> > -       struct map_rb_node *old_node, *next;
> >         struct machine *machine;
> >         bool is_64_bit;
> >         int err, fd;
> > @@ -1292,17 +1302,7 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
> >         }
> >
> >         /* Remove old maps */
> > -       maps__for_each_entry_safe(kmaps, old_node, next) {
> > -               struct map *old_map = old_node->map;
> > -
> > -               /*
> > -                * We need to preserve eBPF maps even if they are
> > -                * covered by kcore, because we need to access
> > -                * eBPF dso for source data.
> > -                */
> > -               if (old_map != map && !__map__is_bpf_prog(old_map))
> > -                       maps__remove(kmaps, old_map);
> > -       }
> > +       maps__remove_maps(kmaps, remove_old_maps, map);
> >         machine->trampolines_mapped = false;
> >
> >         /* Find the kernel map using the '_stext' symbol */
> > --
> > 2.43.0.rc1.413.gea7ed67945-goog
> >
diff mbox series

Patch

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 00e6589bba10..f13fd3a9686b 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -13,6 +13,10 @@ 
 #define maps__for_each_entry(maps, map) \
 	for (map = maps__first(maps); map; map = map_rb_node__next(map))
 
+#define maps__for_each_entry_safe(maps, map, next) \
+	for (map = maps__first(maps), next = map_rb_node__next(map); map; \
+	     map = next, next = map_rb_node__next(map))
+
 static void maps__init(struct maps *maps, struct machine *machine)
 {
 	refcount_set(maps__refcnt(maps), 1);
@@ -214,6 +218,26 @@  int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data)
 	return ret;
 }
 
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data)
+{
+	struct map_rb_node *pos, *next;
+	unsigned int start_nr_maps;
+
+	down_write(maps__lock(maps));
+
+	start_nr_maps = maps__nr_maps(maps);
+	maps__for_each_entry_safe(maps, pos, next)	{
+		if (cb(pos->map, data)) {
+			__maps__remove(maps, pos);
+			--RC_CHK_ACCESS(maps)->nr_maps;
+		}
+	}
+	if (maps__maps_by_name(maps) && start_nr_maps != maps__nr_maps(maps))
+		__maps__free_maps_by_name(maps);
+
+	up_write(maps__lock(maps));
+}
+
 struct symbol *maps__find_symbol(struct maps *maps, u64 addr, struct map **mapp)
 {
 	struct map *map = maps__find(maps, addr);
diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
index 8ac30cdaf5bd..b94ad5c8fea7 100644
--- a/tools/perf/util/maps.h
+++ b/tools/perf/util/maps.h
@@ -36,10 +36,6 @@  struct map_rb_node *map_rb_node__next(struct map_rb_node *node);
 struct map_rb_node *maps__find_node(struct maps *maps, struct map *map);
 struct map *maps__find(struct maps *maps, u64 addr);
 
-#define maps__for_each_entry_safe(maps, map, next) \
-	for (map = maps__first(maps), next = map_rb_node__next(map); map; \
-	     map = next, next = map_rb_node__next(map))
-
 DECLARE_RC_STRUCT(maps) {
 	struct rb_root      entries;
 	struct rw_semaphore lock;
@@ -80,6 +76,8 @@  static inline void __maps__zput(struct maps **map)
 
 /* Iterate over map calling cb for each entry. */
 int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data), void *data);
+/* Iterate over map removing an entry if cb returns true. */
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data);
 
 static inline struct rb_root *maps__entries(struct maps *maps)
 {
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 72f03b875478..30da8a405d11 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1239,13 +1239,23 @@  static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
 	return 0;
 }
 
+static bool remove_old_maps(struct map *map, void *data)
+{
+	const struct map *map_to_save = data;
+
+	/*
+	 * We need to preserve eBPF maps even if they are covered by kcore,
+	 * because we need to access eBPF dso for source data.
+	 */
+	return RC_CHK_ACCESS(map) != RC_CHK_ACCESS(map_to_save) && !__map__is_bpf_prog(map);
+}
+
 static int dso__load_kcore(struct dso *dso, struct map *map,
 			   const char *kallsyms_filename)
 {
 	struct maps *kmaps = map__kmaps(map);
 	struct kcore_mapfn_data md;
 	struct map *replacement_map = NULL;
-	struct map_rb_node *old_node, *next;
 	struct machine *machine;
 	bool is_64_bit;
 	int err, fd;
@@ -1292,17 +1302,7 @@  static int dso__load_kcore(struct dso *dso, struct map *map,
 	}
 
 	/* Remove old maps */
-	maps__for_each_entry_safe(kmaps, old_node, next) {
-		struct map *old_map = old_node->map;
-
-		/*
-		 * We need to preserve eBPF maps even if they are
-		 * covered by kcore, because we need to access
-		 * eBPF dso for source data.
-		 */
-		if (old_map != map && !__map__is_bpf_prog(old_map))
-			maps__remove(kmaps, old_map);
-	}
+	maps__remove_maps(kmaps, remove_old_maps, map);
 	machine->trampolines_mapped = false;
 
 	/* Find the kernel map using the '_stext' symbol */