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 --- include/sound/hdaudio.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/sound') diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h index 96546b30e900..6f1118545bb8 100644 --- a/include/sound/hdaudio.h +++ b/include/sound/hdaudio.h @@ -111,8 +111,7 @@ void snd_hdac_device_unregister(struct hdac_device *codec); int snd_hdac_device_set_chip_name(struct hdac_device *codec, const char *name); int snd_hdac_codec_modalias(struct hdac_device *hdac, char *buf, size_t size); -int snd_hdac_refresh_widgets(struct hdac_device *codec); -int snd_hdac_refresh_widget_sysfs(struct hdac_device *codec); +int snd_hdac_refresh_widgets(struct hdac_device *codec, bool sysfs); unsigned int snd_hdac_make_cmd(struct hdac_device *codec, hda_nid_t nid, unsigned int verb, unsigned int parm); -- cgit v1.2.3