ALSA: hda - Fix concurrent hash accesses

The amp and caps hashes aren't protected properly for concurrent
accesses.  Protect them via a new mutex now.

But it can't be so simple as originally thought: since the update of a
hash table entry itself might trigger the power-up sequence which
again accesses the hash table, we can't cover the whole function
simply via mutex.  Thus the update part has to be split from the mutex
and revalidated.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 121 insertions, 81 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 5e7c4bf83abe..7a621f5986e0 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -1255,6 +1255,7 @@ int /*__devinit*/ snd_hda_codec_new(struct hda_bus *bus,
         codec->addr = codec_addr;
         mutex_init(&codec->spdif_mutex);
         mutex_init(&codec->control_mutex);
+        mutex_init(&codec->hash_mutex);
         init_hda_cache(&codec->amp_cache, sizeof(struct hda_amp_info));
         init_hda_cache(&codec->cmd_cache, sizeof(struct hda_cache_head));
         snd_array_init(&codec->mixers, sizeof(struct hda_nid_item), 32);
@@ -1605,6 +1606,60 @@ get_alloc_amp_hash(struct hda_codec *codec, u32 key)
         return (struct hda_amp_info *)get_alloc_hash(&codec->amp_cache, key);
 }
 
+/* overwrite the value with the key in the caps hash */
+static int write_caps_hash(struct hda_codec *codec, u32 key, unsigned int val)
+{
+        struct hda_amp_info *info;
+
+        mutex_lock(&codec->hash_mutex);
+        info = get_alloc_amp_hash(codec, key);
+        if (!info) {
+                mutex_unlock(&codec->hash_mutex);
+                return -EINVAL;
+        }
+        info->amp_caps = val;
+        info->head.val |= INFO_AMP_CAPS;
+        mutex_unlock(&codec->hash_mutex);
+        return 0;
+}
+
+/* query the value from the caps hash; if not found, fetch the current
+ * value from the given function and store in the hash
+ */
+static unsigned int
+query_caps_hash(struct hda_codec *codec, hda_nid_t nid, int dir, u32 key,
+                unsigned int (*func)(struct hda_codec *, hda_nid_t, int))
+{
+        struct hda_amp_info *info;
+        unsigned int val;
+
+        mutex_lock(&codec->hash_mutex);
+        info = get_alloc_amp_hash(codec, key);
+        if (!info) {
+                mutex_unlock(&codec->hash_mutex);
+                return 0;
+        }
+        if (!(info->head.val & INFO_AMP_CAPS)) {
+                mutex_unlock(&codec->hash_mutex); /* for reentrance */
+                val = func(codec, nid, dir);
+                write_caps_hash(codec, key, val);
+        } else {
+                val = info->amp_caps;
+                mutex_unlock(&codec->hash_mutex);
+        }
+        return val;
+}
+
+static unsigned int read_amp_cap(struct hda_codec *codec, hda_nid_t nid,
+                                 int direction)
+{
+        if (!(get_wcaps(codec, nid) & AC_WCAP_AMP_OVRD))
+                nid = codec->afg;
+        return snd_hda_param_read(codec, nid,
+                                  direction == HDA_OUTPUT ?
+                                  AC_PAR_AMP_OUT_CAP : AC_PAR_AMP_IN_CAP);
+}
+
 /**
  * query_amp_caps - query AMP capabilities
  * @codec: the HD-auio codec
@@ -1619,22 +1674,9 @@ get_alloc_amp_hash(struct hda_codec *codec, u32 key)
  */
 u32 query_amp_caps(struct hda_codec *codec, hda_nid_t nid, int direction)
 {
-        struct hda_amp_info *info;
-
-        info = get_alloc_amp_hash(codec, HDA_HASH_KEY(nid, direction, 0));
-        if (!info)
-                return 0;
-        if (!(info->head.val & INFO_AMP_CAPS)) {
-                if (!(get_wcaps(codec, nid) & AC_WCAP_AMP_OVRD))
-                        nid = codec->afg;
-                info->amp_caps = snd_hda_param_read(codec, nid,
-                                                    direction == HDA_OUTPUT ?
-                                                    AC_PAR_AMP_OUT_CAP :
-                                                    AC_PAR_AMP_IN_CAP);
-                if (info->amp_caps)
-                        info->head.val |= INFO_AMP_CAPS;
-        }
-        return info->amp_caps;
+        return query_caps_hash(codec, nid, direction,
+                               HDA_HASH_KEY(nid, direction, 0),
+                               read_amp_cap);
 }
 EXPORT_SYMBOL_HDA(query_amp_caps);
 
@@ -1654,34 +1696,12 @@ EXPORT_SYMBOL_HDA(query_amp_caps);
 int snd_hda_override_amp_caps(struct hda_codec *codec, hda_nid_t nid, int dir,
                               unsigned int caps)
 {
-        struct hda_amp_info *info;
-
-        info = get_alloc_amp_hash(codec, HDA_HASH_KEY(nid, dir, 0));
-        if (!info)
-                return -EINVAL;
-        info->amp_caps = caps;
-        info->head.val |= INFO_AMP_CAPS;
-        return 0;
+        return write_caps_hash(codec, HDA_HASH_KEY(nid, dir, 0), caps);
 }
 EXPORT_SYMBOL_HDA(snd_hda_override_amp_caps);
 
-static unsigned int
-query_caps_hash(struct hda_codec *codec, hda_nid_t nid, u32 key,
-                unsigned int (*func)(struct hda_codec *, hda_nid_t))
-{
-        struct hda_amp_info *info;
-
-        info = get_alloc_amp_hash(codec, key);
-        if (!info)
-                return 0;
-        if (!info->head.val) {
-                info->head.val |= INFO_AMP_CAPS;
-                info->amp_caps = func(codec, nid);
-        }
-        return info->amp_caps;
-}
-
-static unsigned int read_pin_cap(struct hda_codec *codec, hda_nid_t nid)
+static unsigned int read_pin_cap(struct hda_codec *codec, hda_nid_t nid,
+                                 int dir)
 {
         return snd_hda_param_read(codec, nid, AC_PAR_PIN_CAP);
 }
@@ -1699,7 +1719,7 @@ static unsigned int read_pin_cap(struct hda_codec *codec, hda_nid_t nid)
  */
 u32 snd_hda_query_pin_caps(struct hda_codec *codec, hda_nid_t nid)
 {
-        return query_caps_hash(codec, nid, HDA_HASH_PINCAP_KEY(nid),
+        return query_caps_hash(codec, nid, 0, HDA_HASH_PINCAP_KEY(nid),
                                read_pin_cap);
 }
 EXPORT_SYMBOL_HDA(snd_hda_query_pin_caps);
@@ -1717,41 +1737,47 @@ EXPORT_SYMBOL_HDA(snd_hda_query_pin_caps);
 int snd_hda_override_pin_caps(struct hda_codec *codec, hda_nid_t nid,
                               unsigned int caps)
 {
-        struct hda_amp_info *info;
-        info = get_alloc_amp_hash(codec, HDA_HASH_PINCAP_KEY(nid));
-        if (!info)
-                return -ENOMEM;
-        info->amp_caps = caps;
-        info->head.val |= INFO_AMP_CAPS;
-        return 0;
+        return write_caps_hash(codec, HDA_HASH_PINCAP_KEY(nid), caps);
 }
 EXPORT_SYMBOL_HDA(snd_hda_override_pin_caps);
 
-/*
- * read the current volume to info
- * if the cache exists, read the cache value.
+/* read or sync the hash value with the current value;
+ * call within hash_mutex
  */
-static unsigned int get_vol_mute(struct hda_codec *codec,
-                                 struct hda_amp_info *info, hda_nid_t nid,
-                                 int ch, int direction, int index)
+static struct hda_amp_info *
+update_amp_hash(struct hda_codec *codec, hda_nid_t nid, int ch,
+                int direction, int index)
 {
-        u32 val, parm;
-
-        if (info->head.val & INFO_AMP_VOL(ch))
-                return info->vol[ch];
+        struct hda_amp_info *info;
+        unsigned int parm, val = 0;
+        bool val_read = false;
 
-        parm = ch ? AC_AMP_GET_RIGHT : AC_AMP_GET_LEFT;
-        parm |= direction == HDA_OUTPUT ? AC_AMP_GET_OUTPUT : AC_AMP_GET_INPUT;
-        parm |= index;
-        val = snd_hda_codec_read(codec, nid, 0,
+ retry:
+        info = get_alloc_amp_hash(codec, HDA_HASH_KEY(nid, direction, index));
+        if (!info)
+                return NULL;
+        if (!(info->head.val & INFO_AMP_VOL(ch))) {
+                if (!val_read) {
+                        mutex_unlock(&codec->hash_mutex);
+                        parm = ch ? AC_AMP_GET_RIGHT : AC_AMP_GET_LEFT;
+                        parm |= direction == HDA_OUTPUT ?
+                                AC_AMP_GET_OUTPUT : AC_AMP_GET_INPUT;
+                        parm |= index;
+                        val = snd_hda_codec_read(codec, nid, 0,
                                  AC_VERB_GET_AMP_GAIN_MUTE, parm);
-        info->vol[ch] = val & 0xff;
-        info->head.val |= INFO_AMP_VOL(ch);
-        return info->vol[ch];
+                        val &= 0xff;
+                        val_read = true;
+                        mutex_lock(&codec->hash_mutex);
+                        goto retry;
+                }
+                info->vol[ch] = val;
+                info->head.val |= INFO_AMP_VOL(ch);
+        }
+        return info;
 }
 
 /*
- * write the current volume in info to the h/w and update the cache
+ * write the current volume in info to the h/w
  */
 static void put_vol_mute(struct hda_codec *codec, struct hda_amp_info *info,
                          hda_nid_t nid, int ch, int direction, int index,
@@ -1768,7 +1794,6 @@ static void put_vol_mute(struct hda_codec *codec, struct hda_amp_info *info,
         else
                 parm |= val;
         snd_hda_codec_write(codec, nid, 0, AC_VERB_SET_AMP_GAIN_MUTE, parm);
-        info->vol[ch] = val;
 }
 
 /**
@@ -1785,10 +1810,14 @@ int snd_hda_codec_amp_read(struct hda_codec *codec, hda_nid_t nid, int ch,
                            int direction, int index)
 {
         struct hda_amp_info *info;
-        info = get_alloc_amp_hash(codec, HDA_HASH_KEY(nid, direction, index));
-        if (!info)
-                return 0;
-        return get_vol_mute(codec, info, nid, ch, direction, index);
+        unsigned int val = 0;
+
+        mutex_lock(&codec->hash_mutex);
+        info = update_amp_hash(codec, nid, ch, direction, index);
+        if (info)
+                val = info->vol[ch];
+        mutex_unlock(&codec->hash_mutex);
+        return val;
 }
 EXPORT_SYMBOL_HDA(snd_hda_codec_amp_read);
 
@@ -1810,15 +1839,23 @@ int snd_hda_codec_amp_update(struct hda_codec *codec, hda_nid_t nid, int ch,
 {
         struct hda_amp_info *info;
 
-        info = get_alloc_amp_hash(codec, HDA_HASH_KEY(nid, direction, idx));
-        if (!info)
-                return 0;
         if (snd_BUG_ON(mask & ~0xff))
                 mask &= 0xff;
         val &= mask;
-        val |= get_vol_mute(codec, info, nid, ch, direction, idx) & ~mask;
-        if (info->vol[ch] == val)
+
+        mutex_lock(&codec->hash_mutex);
+        info = update_amp_hash(codec, nid, ch, direction, idx);
+        if (!info) {
+                mutex_unlock(&codec->hash_mutex);
+                return 0;
+        }
+        val |= info->vol[ch] & ~mask;
+        if (info->vol[ch] == val) {
+                mutex_unlock(&codec->hash_mutex);
                 return 0;
+        }
+        info->vol[ch] = val;
+        mutex_unlock(&codec->hash_mutex);
         put_vol_mute(codec, info, nid, ch, direction, idx, val);
         return 1;
 }
@@ -3693,7 +3730,8 @@ unsigned int snd_hda_calc_stream_format(unsigned int rate,
 }
 EXPORT_SYMBOL_HDA(snd_hda_calc_stream_format);
 
-static unsigned int get_pcm_param(struct hda_codec *codec, hda_nid_t nid)
+static unsigned int get_pcm_param(struct hda_codec *codec, hda_nid_t nid,
+                                  int dir)
 {
         unsigned int val = 0;
         if (nid != codec->afg &&
@@ -3708,11 +3746,12 @@ static unsigned int get_pcm_param(struct hda_codec *codec, hda_nid_t nid)
 
 static unsigned int query_pcm_param(struct hda_codec *codec, hda_nid_t nid)
 {
-        return query_caps_hash(codec, nid, HDA_HASH_PARPCM_KEY(nid),
+        return query_caps_hash(codec, nid, 0, HDA_HASH_PARPCM_KEY(nid),
                                get_pcm_param);
 }
 
-static unsigned int get_stream_param(struct hda_codec *codec, hda_nid_t nid)
+static unsigned int get_stream_param(struct hda_codec *codec, hda_nid_t nid,
+                                     int dir)
 {
         unsigned int streams = snd_hda_param_read(codec, nid, AC_PAR_STREAM);
         if (!streams || streams == -1)
@@ -3724,7 +3763,7 @@ static unsigned int get_stream_param(struct hda_codec *codec, hda_nid_t nid)
 
 static unsigned int query_stream_param(struct hda_codec *codec, hda_nid_t nid)
 {
-        return query_caps_hash(codec, nid, HDA_HASH_PARSTR_KEY(nid),
+        return query_caps_hash(codec, nid, 0, HDA_HASH_PARSTR_KEY(nid),
                                get_stream_param);
 }
 
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index fce30b42bc46..29a311b05f2d 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -827,6 +827,7 @@ struct hda_codec {
 
         struct mutex spdif_mutex;
         struct mutex control_mutex;
+        struct mutex hash_mutex;
         struct snd_array spdif_out;
         unsigned int spdif_in_enable;   /* SPDIF input enable? */
         const hda_nid_t *slave_dig_outs; /* optional digital out slave widgets */