[PATCH weston] text_backend: make destructor call explicit
Derek Foreman
derekf at osg.samsung.com
Thu Jun 25 07:01:57 PDT 2015
On 24/06/15 08:28 AM, Pekka Paalanen wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
>
> We used to rely on the order in which the
> weston_compositor::destroy_signal callbacks happened, to not access
> freed memory. Don't know when, but this broke at least with ivi-shell,
> which caused crashes in random places on compositor shutdown.
FWIW, I first noticed this breakage at 9a51cd7d but I didn't really try
to figure out if it was newly introduced or a problem that was just even
harder to trigger before that point. :)
> Valgrind found the following:
>
> Invalid write of size 8
> at 0xC2EDC69: unbind_input_panel (input-panel-ivi.c:340)
> by 0x4E3B6BB: destroy_resource (wayland-server.c:537)
> by 0x4E3E085: for_each_helper.isra.0 (wayland-util.c:359)
> by 0x4E3E60D: wl_map_for_each (wayland-util.c:365)
> by 0x4E3BEC7: wl_client_destroy (wayland-server.c:675)
> by 0x4182F2: text_backend_notifier_destroy (text-backend.c:1047)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
> Address 0x67ea360 is 208 bytes inside a block of size 232 free'd
> at 0x4C2A6BC: free (vg_replace_malloc.c:473)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
>
> Invalid write of size 8
> at 0x4E3E0D7: wl_list_remove (wayland-util.c:57)
> by 0xC2EDEE9: destroy_input_panel_surface (input-panel-ivi.c:191)
> by 0x4E3B6BB: destroy_resource (wayland-server.c:537)
> by 0x4E3BC7B: wl_resource_destroy (wayland-server.c:550)
> by 0x40DB8B: wl_signal_emit (wayland-server-core.h:264)
> by 0x40DB8B: weston_surface_destroy (compositor.c:1883)
> by 0x40DB8B: weston_surface_destroy (compositor.c:1873)
> by 0x4E3B6BB: destroy_resource (wayland-server.c:537)
> by 0x4E3E085: for_each_helper.isra.0 (wayland-util.c:359)
> by 0x4E3E60D: wl_map_for_each (wayland-util.c:365)
> by 0x4E3BEC7: wl_client_destroy (wayland-server.c:675)
> by 0x4182F2: text_backend_notifier_destroy (text-backend.c:1047)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
> Address 0x67ea370 is 224 bytes inside a block of size 232 free'd
> at 0x4C2A6BC: free (vg_replace_malloc.c:473)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
>
> Invalid write of size 8
> at 0x4E3E0E7: wl_list_remove (wayland-util.c:58)
> by 0xC2EDEE9: destroy_input_panel_surface (input-panel-ivi.c:191)
> by 0x4E3B6BB: destroy_resource (wayland-server.c:537)
> by 0x4E3BC7B: wl_resource_destroy (wayland-server.c:550)
> by 0x40DB8B: wl_signal_emit (wayland-server-core.h:264)
> by 0x40DB8B: weston_surface_destroy (compositor.c:1883)
> by 0x40DB8B: weston_surface_destroy (compositor.c:1873)
> by 0x4E3B6BB: destroy_resource (wayland-server.c:537)
> by 0x4E3E085: for_each_helper.isra.0 (wayland-util.c:359)
> by 0x4E3E60D: wl_map_for_each (wayland-util.c:365)
> by 0x4E3BEC7: wl_client_destroy (wayland-server.c:675)
> by 0x4182F2: text_backend_notifier_destroy (text-backend.c:1047)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
> Address 0x67ea368 is 216 bytes inside a block of size 232 free'd
> at 0x4C2A6BC: free (vg_replace_malloc.c:473)
> by 0x4084FB: wl_signal_emit (wayland-server-core.h:264)
> by 0x4084FB: main (compositor.c:5465)
>
> Looking at the first of these, unbind_input_panel() gets called when the
> text-backend destroys its helper client which has bound to input_panel
> interface. This happens after the shell's destroy_signal callback has
> been called, so the shell has already been freed.
>
> The other two errors come from
> wl_list_remove(&input_panel_surface->link);
> which has gone stale when the shell was destroyed
> (shell->input_panel.surfaces list).
>
> Rather than creating even more destroy listeners and hooking them up in
> spaghetti, modify text-backend to not hook up to the compositor destroy
> signal. Instead, make it the text_backend_init() callers' responsibility
> to also call text_backend_destroy() appropriately, before the shell goes
> away.
haha, the destroy listener is how I tried to fix it in
patchwork.freedesktop.org/patch/52013
I'll close that ticket.
This looks correct to me, and I'm no longer able to reproduce the crash.
Reviewed-By: Derek Foreman <derekf at osg.samsung.com>
Tested-By: Derek Foreman <derekf at osg.samsung.com>
> This fixed all the above Valgrind errors, and avoid a crash with
> ivi-shell when exiting Weston.
>
> Also using desktop-shell exhibited similar Valgrind errors which are
> fixed by this patch, but those didn't happen to cause any crashes AFAIK.
>
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> ---
> desktop-shell/shell.c | 4 +++-
> desktop-shell/shell.h | 2 ++
> ivi-shell/ivi-shell.c | 4 +++-
> ivi-shell/ivi-shell.h | 2 ++
> src/compositor.h | 7 ++++++-
> src/text-backend.c | 18 +++++-------------
> 6 files changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
> index 0fe4658..ed7e896 100644
> --- a/desktop-shell/shell.c
> +++ b/desktop-shell/shell.c
> @@ -6347,6 +6347,7 @@ shell_destroy(struct wl_listener *listener, void *data)
> wl_list_remove(&shell->idle_listener.link);
> wl_list_remove(&shell->wake_listener.link);
>
> + text_backend_destroy(shell->text_backend);
> input_panel_destroy(shell);
>
> wl_list_for_each_safe(shell_output, tmp, &shell->output_list, link) {
> @@ -6513,7 +6514,8 @@ module_init(struct weston_compositor *ec,
> if (input_panel_setup(shell) < 0)
> return -1;
>
> - if (text_backend_init(ec) < 0)
> + shell->text_backend = text_backend_init(ec);
> + if (!shell->text_backend)
> return -1;
>
> shell_configuration(shell);
> diff --git a/desktop-shell/shell.h b/desktop-shell/shell.h
> index f76f181..c0585a2 100644
> --- a/desktop-shell/shell.h
> +++ b/desktop-shell/shell.h
> @@ -148,6 +148,8 @@ struct desktop_shell {
> bool showing_input_panels;
> bool prepare_event_sent;
>
> + struct text_backend *text_backend;
> +
> struct {
> struct weston_surface *surface;
> pixman_box32_t cursor_rectangle;
> diff --git a/ivi-shell/ivi-shell.c b/ivi-shell/ivi-shell.c
> index 896ba1b..f958fd4 100644
> --- a/ivi-shell/ivi-shell.c
> +++ b/ivi-shell/ivi-shell.c
> @@ -343,6 +343,7 @@ shell_destroy(struct wl_listener *listener, void *data)
> container_of(listener, struct ivi_shell, destroy_listener);
> struct ivi_shell_surface *ivisurf, *next;
>
> + text_backend_destroy(shell->text_backend);
> input_panel_destroy(shell);
>
> wl_list_for_each_safe(ivisurf, next, &shell->ivi_surface_list, link) {
> @@ -439,7 +440,8 @@ module_init(struct weston_compositor *compositor,
> if (input_panel_setup(shell) < 0)
> goto out_settings;
>
> - if (text_backend_init(compositor) < 0)
> + shell->text_backend = text_backend_init(compositor);
> + if (!shell->text_backend)
> goto out_settings;
>
> if (wl_global_create(compositor->wl_display,
> diff --git a/ivi-shell/ivi-shell.h b/ivi-shell/ivi-shell.h
> index bd2571e..9a05eb2 100644
> --- a/ivi-shell/ivi-shell.h
> +++ b/ivi-shell/ivi-shell.h
> @@ -35,6 +35,8 @@ struct ivi_shell
>
> struct wl_list ivi_surface_list; /* struct ivi_shell_surface::link */
>
> + struct text_backend *text_backend;
> +
> struct wl_listener show_input_panel_listener;
> struct wl_listener hide_input_panel_listener;
> struct wl_listener update_input_panel_listener;
> diff --git a/src/compositor.h b/src/compositor.h
> index 3586f5b..9069fe1 100644
> --- a/src/compositor.h
> +++ b/src/compositor.h
> @@ -1456,9 +1456,14 @@ weston_screenshooter_shoot(struct weston_output *output, struct weston_buffer *b
> struct clipboard *
> clipboard_create(struct weston_seat *seat);
>
> -int
> +struct text_backend;
> +
> +struct text_backend *
> text_backend_init(struct weston_compositor *ec);
>
> +void
> +text_backend_destroy(struct text_backend *text_backend);
> +
> struct weston_process;
> typedef void (*weston_process_cleanup_func_t)(struct weston_process *process,
> int status);
> diff --git a/src/text-backend.c b/src/text-backend.c
> index 55013a2..9485f7e 100644
> --- a/src/text-backend.c
> +++ b/src/text-backend.c
> @@ -109,7 +109,6 @@ struct text_backend {
> } input_method;
>
> struct wl_listener seat_created_listener;
> - struct wl_listener destroy_listener;
> };
>
> static void
> @@ -1037,21 +1036,17 @@ text_backend_configuration(struct text_backend *text_backend)
> free(client);
> }
>
> -static void
> -text_backend_notifier_destroy(struct wl_listener *listener, void *data)
> +WL_EXPORT void
> +text_backend_destroy(struct text_backend *text_backend)
> {
> - struct text_backend *text_backend =
> - container_of(listener, struct text_backend, destroy_listener);
> -
> if (text_backend->input_method.client)
> wl_client_destroy(text_backend->input_method.client);
>
> free(text_backend->input_method.path);
> -
> free(text_backend);
> }
>
> -WL_EXPORT int
> +WL_EXPORT struct text_backend *
> text_backend_init(struct weston_compositor *ec)
> {
> struct text_backend *text_backend;
> @@ -1059,7 +1054,7 @@ text_backend_init(struct weston_compositor *ec)
>
> text_backend = zalloc(sizeof(*text_backend));
> if (text_backend == NULL)
> - return -1;
> + return NULL;
>
> text_backend->compositor = ec;
>
> @@ -1071,10 +1066,7 @@ text_backend_init(struct weston_compositor *ec)
> wl_signal_add(&ec->seat_created_signal,
> &text_backend->seat_created_listener);
>
> - text_backend->destroy_listener.notify = text_backend_notifier_destroy;
> - wl_signal_add(&ec->destroy_signal, &text_backend->destroy_listener);
> -
> text_input_manager_create(ec);
>
> - return 0;
> + return text_backend;
> }
>
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