ALSA: hda: Fix race between creating and refreshing sysfs entries

hda_widget_sysfs_reinit() can free underlying codec->widgets structure
on which widget_tree_create() operates. Add locking to prevent such
issues from happening.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110382
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h
index ca1d9a7..5a9315a 100644 (file)
--- a/include/sound/hdaudio.h
+++ b/include/sound/hdaudio.h
@@ -81,6 +81,7 @@ struct hdac_device {
        atomic_t in_pm;         /* suspend/resume being performed */
 
        /* sysfs */
+       struct mutex widget_lock;
        struct hdac_widget_tree *widgets;
 
        /* regmap */

diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c
index 95b073e..4769f4c 100644 (file)
--- a/sound/hda/hdac_device.c
+++ b/sound/hda/hdac_device.c
@@ -55,6 +55,7 @@ int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
        codec->bus = bus;
        codec->addr = addr;
        codec->type = HDA_DEV_CORE;
+       mutex_init(&codec->widget_lock);
        pm_runtime_set_active(&codec->dev);
        pm_runtime_get_noresume(&codec->dev);
        atomic_set(&codec->in_pm, 0);
@@ -141,7 +142,9 @@ int snd_hdac_device_register(struct hdac_device *codec)
        err = device_add(&codec->dev);
        if (err < 0)
                return err;
+       mutex_lock(&codec->widget_lock);
        err = hda_widget_sysfs_init(codec);
+       mutex_unlock(&codec->widget_lock);
        if (err < 0) {
                device_del(&codec->dev);
                return err;
@@ -158,7 +161,9 @@ EXPORT_SYMBOL_GPL(snd_hdac_device_register);
 void snd_hdac_device_unregister(struct hdac_device *codec)
 {
        if (device_is_registered(&codec->dev)) {
+               mutex_lock(&codec->widget_lock);
                hda_widget_sysfs_exit(codec);
+               mutex_unlock(&codec->widget_lock);
                device_del(&codec->dev);
                snd_hdac_bus_remove_device(codec->bus, codec);
        }
@@ -404,7 +409,9 @@ int snd_hdac_refresh_widgets(struct hdac_device *codec, bool sysfs)
        }
 
        if (sysfs) {
+               mutex_lock(&codec->widget_lock);
                err = hda_widget_sysfs_reinit(codec, start_nid, nums);
+               mutex_unlock(&codec->widget_lock);
                if (err < 0)
                        return err;
        }

diff --git a/sound/hda/hdac_sysfs.c b/sound/hda/hdac_sysfs.c
index fb2aa34..909d5ef 100644 (file)
--- a/sound/hda/hdac_sysfs.c
+++ b/sound/hda/hdac_sysfs.c
@@ -395,6 +395,7 @@ static int widget_tree_create(struct hdac_device *codec)
        return 0;
 }
 
+/* call with codec->widget_lock held */
 int hda_widget_sysfs_init(struct hdac_device *codec)
 {
        int err;
@@ -411,11 +412,13 @@ int hda_widget_sysfs_init(struct hdac_device *codec)
        return 0;
 }
 
+/* call with codec->widget_lock held */
 void hda_widget_sysfs_exit(struct hdac_device *codec)
 {
        widget_tree_free(codec);
 }
 
+/* call with codec->widget_lock held */
 int hda_widget_sysfs_reinit(struct hdac_device *codec,
                            hda_nid_t start_nid, int num_nodes)
 {