[alsa-devel] [PATCH v2 3/4] ALSA: hda - hdmi: protect access to ELD buffer
David Henningsson
david.henningsson at canonical.com
Tue Feb 19 10:45:40 CET 2013
On 02/19/2013 10:15 AM, Takashi Iwai wrote:
> At Tue, 19 Feb 2013 09:47:36 +0100,
> David Henningsson wrote:
>>
>> Because the eld buffer can be simultaneously accessed from both
>> workqueue context (updating) and process context (kcontrol read),
>> we need to protect it with a spinlock to guarantee consistency.
>
> We can't use a spinlock for snd_iprintf(), as this involves with
> vmalloc(). Use a mutex intead.
Ok, thanks for spotting.
>> To avoid holding the spinlock while reading the ELD info from the
>> codec, we introduce a temporary eld buffer.
>
> Looking through the patches, it's better to split to a few parts now:
>
> struct parsed_hdmi_eld {
> bool monitor_present;
> ....
> };
>
> struct hdmi_eld {
> char eld_buffer[ELD_MAX_SIZE];
> struct parsed_hdmi_eld info;
> struct mutex lock;
> #ifdef CONFIG_PROC_FS
> struct snd_info_entry *proc_entry;
> #endif
> };
>
> In that way, you can avoid the hack like offset() calculation in
> patch_hdmi.c. The comparison can be done only for eld_buffer[], too.
This sounds like a good idea. I will do it. I think eld_valid and
monitor_present should be in hdmi_eld and not parsed_hdmi_eld, because
those fields do not come from the raw ELD info.
>
>
> thanks,
>
> Takashi
>
>>
>> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
>> ---
>> sound/pci/hda/hda_eld.c | 12 +++++++++---
>> sound/pci/hda/hda_local.h | 3 +++
>> sound/pci/hda/patch_hdmi.c | 32 +++++++++++++++++++++++++-------
>> 3 files changed, 37 insertions(+), 10 deletions(-)
>>
>> diff --git a/sound/pci/hda/hda_eld.c b/sound/pci/hda/hda_eld.c
>> index 4c054f4..766f011 100644
>> --- a/sound/pci/hda/hda_eld.c
>> +++ b/sound/pci/hda/hda_eld.c
>> @@ -490,7 +490,7 @@ static void hdmi_print_eld_info(struct snd_info_entry *entry,
>> struct hdmi_eld *e = entry->private_data;
>> char buf[SND_PRINT_CHANNEL_ALLOCATION_ADVISED_BUFSIZE];
>> int i;
>> - static char *eld_versoin_names[32] = {
>> + static char *eld_version_names[32] = {
>> "reserved",
>> "reserved",
>> "CEA-861D or below",
>> @@ -505,15 +505,18 @@ static void hdmi_print_eld_info(struct snd_info_entry *entry,
>> [4 ... 7] = "reserved"
>> };
>>
>> + spin_lock(&e->lock);
>> snd_iprintf(buffer, "monitor_present\t\t%d\n", e->monitor_present);
>> snd_iprintf(buffer, "eld_valid\t\t%d\n", e->eld_valid);
>> - if (!e->eld_valid)
>> + if (!e->eld_valid) {
>> + spin_unlock(&e->lock);
>> return;
>> + }
>> snd_iprintf(buffer, "monitor_name\t\t%s\n", e->monitor_name);
>> snd_iprintf(buffer, "connection_type\t\t%s\n",
>> eld_connection_type_names[e->conn_type]);
>> snd_iprintf(buffer, "eld_version\t\t[0x%x] %s\n", e->eld_ver,
>> - eld_versoin_names[e->eld_ver]);
>> + eld_version_names[e->eld_ver]);
>> snd_iprintf(buffer, "edid_version\t\t[0x%x] %s\n", e->cea_edid_ver,
>> cea_edid_version_names[e->cea_edid_ver]);
>> snd_iprintf(buffer, "manufacture_id\t\t0x%x\n", e->manufacture_id);
>> @@ -530,6 +533,7 @@ static void hdmi_print_eld_info(struct snd_info_entry *entry,
>>
>> for (i = 0; i < e->sad_count; i++)
>> hdmi_print_sad_info(i, e->sad + i, buffer);
>> + spin_unlock(&e->lock);
>> }
>>
>> static void hdmi_write_eld_info(struct snd_info_entry *entry,
>> @@ -542,6 +546,7 @@ static void hdmi_write_eld_info(struct snd_info_entry *entry,
>> long long val;
>> unsigned int n;
>>
>> + spin_lock(&e->lock);
>> while (!snd_info_get_line(buffer, line, sizeof(line))) {
>> if (sscanf(line, "%s %llx", name, &val) != 2)
>> continue;
>> @@ -593,6 +598,7 @@ static void hdmi_write_eld_info(struct snd_info_entry *entry,
>> e->sad_count = n + 1;
>> }
>> }
>> + spin_unlock(&e->lock);
>> }
>>
>>
>> diff --git a/sound/pci/hda/hda_local.h b/sound/pci/hda/hda_local.h
>> index 05f1d59..b2d6a9e 100644
>> --- a/sound/pci/hda/hda_local.h
>> +++ b/sound/pci/hda/hda_local.h
>> @@ -712,8 +712,11 @@ struct cea_sad {
>>
>> /*
>> * ELD: EDID Like Data
>> + *
>> + * Note: The order of these fields is used in hdmi_present_sense
>> */
>> struct hdmi_eld {
>> + spinlock_t lock;
>> bool monitor_present;
>> bool eld_valid;
>> int eld_size;
>> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
>> index 7a73dfb..52b1afc 100644
>> --- a/sound/pci/hda/patch_hdmi.c
>> +++ b/sound/pci/hda/patch_hdmi.c
>> @@ -91,6 +91,7 @@ struct hdmi_spec {
>> struct hda_pcm pcm_rec[MAX_HDMI_PINS];
>> unsigned int channels_max; /* max over all cvts */
>>
>> + struct hdmi_eld temp_eld;
>> /*
>> * Non-generic ATI/NVIDIA specific
>> */
>> @@ -352,7 +353,9 @@ static int hdmi_eld_ctl_info(struct snd_kcontrol *kcontrol,
>> pin_idx = kcontrol->private_value;
>> eld = &spec->pins[pin_idx].sink_eld;
>>
>> + spin_lock(&eld->lock);
>> uinfo->count = eld->eld_valid ? eld->eld_size : 0;
>> + spin_unlock(&eld->lock);
>>
>> return 0;
>> }
>> @@ -368,7 +371,9 @@ static int hdmi_eld_ctl_get(struct snd_kcontrol *kcontrol,
>> pin_idx = kcontrol->private_value;
>> eld = &spec->pins[pin_idx].sink_eld;
>>
>> + spin_lock(&eld->lock);
>> if (eld->eld_size > ARRAY_SIZE(ucontrol->value.bytes.data)) {
>> + spin_unlock(&eld->lock);
>> snd_BUG();
>> return -EINVAL;
>> }
>> @@ -376,6 +381,7 @@ static int hdmi_eld_ctl_get(struct snd_kcontrol *kcontrol,
>> if (eld->eld_valid)
>> memcpy(ucontrol->value.bytes.data, eld->eld_buffer,
>> eld->eld_size);
>> + spin_unlock(&eld->lock);
>>
>> return 0;
>> }
>> @@ -1162,7 +1168,9 @@ static int hdmi_read_pin_conn(struct hda_codec *codec, int pin_idx)
>> static void hdmi_present_sense(struct hdmi_spec_per_pin *per_pin, int repoll)
>> {
>> struct hda_codec *codec = per_pin->codec;
>> - struct hdmi_eld *eld = &per_pin->sink_eld;
>> + struct hdmi_spec *spec = codec->spec;
>> + struct hdmi_eld *eld = &spec->temp_eld;
>> + struct hdmi_eld *pin_eld = &per_pin->sink_eld;
>> hda_nid_t pin_nid = per_pin->pin_nid;
>> /*
>> * Always execute a GetPinSense verb here, even when called from
>> @@ -1173,28 +1181,37 @@ static void hdmi_present_sense(struct hdmi_spec_per_pin *per_pin, int repoll)
>> * the unsolicited response to avoid custom WARs.
>> */
>> int present = snd_hda_pin_sense(codec, pin_nid);
>> - bool eld_valid = false;
>> + bool update_eld = false;
>>
>> memset(eld, 0, offsetof(struct hdmi_eld, eld_buffer));
>>
>> eld->monitor_present = !!(present & AC_PINSENSE_PRESENCE);
>> if (eld->monitor_present)
>> - eld_valid = !!(present & AC_PINSENSE_ELDV);
>> + eld->eld_valid = !!(present & AC_PINSENSE_ELDV);
>>
>> _snd_printd(SND_PR_VERBOSE,
>> "HDMI status: Codec=%d Pin=%d Presence_Detect=%d ELD_Valid=%d\n",
>> - codec->addr, pin_nid, eld->monitor_present, eld_valid);
>> + codec->addr, pin_nid, eld->monitor_present, eld->eld_valid);
>>
>> - eld->eld_valid = false;
>> - if (eld_valid) {
>> - if (!snd_hdmi_get_eld(eld, codec, pin_nid))
>> + if (eld->eld_valid) {
>> + if (!snd_hdmi_get_eld(eld, codec, pin_nid)) {
>> snd_hdmi_show_eld(eld);
>> + update_eld = true;
>> + }
>> else if (repoll) {
>> queue_delayed_work(codec->bus->workq,
>> &per_pin->work,
>> msecs_to_jiffies(300));
>> }
>> }
>> +
>> + spin_lock(&pin_eld->lock);
>> + if (pin_eld->eld_valid && !eld->eld_valid)
>> + update_eld = true;
>> + if (update_eld)
>> + memcpy(&pin_eld->monitor_present, &eld->monitor_present,
>> + sizeof(struct hdmi_eld) - sizeof(spinlock_t));
>> + spin_unlock(&pin_eld->lock);
>> }
>>
>> static void hdmi_repoll_eld(struct work_struct *work)
>> @@ -1662,6 +1679,7 @@ static int generic_hdmi_init_per_pins(struct hda_codec *codec)
>> struct hdmi_eld *eld = &per_pin->sink_eld;
>>
>> per_pin->codec = codec;
>> + spin_lock_init(&eld->lock);
>> INIT_DELAYED_WORK(&per_pin->work, hdmi_repoll_eld);
>> snd_hda_eld_proc_new(codec, eld, pin_idx);
>> }
>> --
>> 1.7.9.5
>>
>
--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
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