From 9780ded39bef5d22a84bdc39112df93f70a58bdd Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 18 Oct 2017 15:51:59 +0200 Subject: ALSA: hda: Avoid racy recreation of widget kobjects The refresh of HD-audio widget sysfs kobjects via snd_hdac_refresh_widget_sysfs() is slightly racy. The driver recreates the whole tree from scratch after deleting the whole. When CONFIG_DEBUG_KOBJECT_RELEASE option is used, kobject release doesn't happen immediately but delayed, while the re-creation of the same named kobject happens soon after invoking kobject_put(). This may end up with the conflicts of duplicated kobjects, as found in the bug report below. In this patch, we take another approach to refresh the tree: instead of recreating the whole tree, just add the new nodes and delete the non-existing nodes. Since the refresh happens only once at initialization, no longer race would happen. Along with the code change, merge snd_hdac_refresh_widget_sysfs() with the existing snd_hdac_refresh_widgets() with an additional bool flag for simplifying the code. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=197307 Signed-off-by: Takashi Iwai --- sound/hda/hdac_device.c | 43 ++++++++++--------------------------------- 1 file changed, 10 insertions(+), 33 deletions(-) (limited to 'sound/hda/hdac_device.c') diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c index 19deb306facb..06f845e293cb 100644 --- a/sound/hda/hdac_device.c +++ b/sound/hda/hdac_device.c @@ -87,7 +87,7 @@ int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus, fg = codec->afg ? codec->afg : codec->mfg; - err = snd_hdac_refresh_widgets(codec); + err = snd_hdac_refresh_widgets(codec, false); if (err < 0) goto error; @@ -388,11 +388,12 @@ static void setup_fg_nodes(struct hdac_device *codec) /** * snd_hdac_refresh_widgets - Reset the widget start/end nodes * @codec: the codec object + * @sysfs: re-initialize sysfs tree, too */ -int snd_hdac_refresh_widgets(struct hdac_device *codec) +int snd_hdac_refresh_widgets(struct hdac_device *codec, bool sysfs) { hda_nid_t start_nid; - int nums; + int nums, err; nums = snd_hdac_get_sub_nodes(codec, codec->afg, &start_nid); if (!start_nid || nums <= 0 || nums >= 0xff) { @@ -401,6 +402,12 @@ int snd_hdac_refresh_widgets(struct hdac_device *codec) return -EINVAL; } + if (sysfs) { + err = hda_widget_sysfs_reinit(codec, start_nid, nums); + if (err < 0) + return err; + } + codec->num_nodes = nums; codec->start_nid = start_nid; codec->end_nid = start_nid + nums; @@ -408,36 +415,6 @@ int snd_hdac_refresh_widgets(struct hdac_device *codec) } EXPORT_SYMBOL_GPL(snd_hdac_refresh_widgets); -/** - * snd_hdac_refresh_widget_sysfs - Reset the codec widgets and reinit the - * codec sysfs - * @codec: the codec object - * - * first we need to remove sysfs, then refresh widgets and lastly - * recreate it - */ -int snd_hdac_refresh_widget_sysfs(struct hdac_device *codec) -{ - int ret; - - if (device_is_registered(&codec->dev)) - hda_widget_sysfs_exit(codec); - ret = snd_hdac_refresh_widgets(codec); - if (ret) { - dev_err(&codec->dev, "failed to refresh widget: %d\n", ret); - return ret; - } - if (device_is_registered(&codec->dev)) { - ret = hda_widget_sysfs_init(codec); - if (ret) { - dev_err(&codec->dev, "failed to init sysfs: %d\n", ret); - return ret; - } - } - return ret; -} -EXPORT_SYMBOL_GPL(snd_hdac_refresh_widget_sysfs); - /* return CONNLIST_LEN parameter of the given widget */ static unsigned int get_num_conns(struct hdac_device *codec, hda_nid_t nid) { -- cgit v1.2.3