[ALSA] Add O_APPEND flag support to PCM

Added O_APPEND flag support to PCM to enable shared substreams
among multiple processes.  This mechanism is used by dmix and
dsnoop plugins.

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

8 files changed, 99 insertions, 45 deletions

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 9cc021c7ee1..41885f48ad9 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -137,7 +137,7 @@ enum {
  *                                                                           *
  *****************************************************************************/
 
-#define SNDRV_PCM_VERSION               SNDRV_PROTOCOL_VERSION(2, 0, 7)
+#define SNDRV_PCM_VERSION               SNDRV_PROTOCOL_VERSION(2, 0, 8)
 
 typedef unsigned long snd_pcm_uframes_t;
 typedef signed long snd_pcm_sframes_t;
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 998bacefc8f..cebf0310a8d 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -368,7 +368,8 @@ struct snd_pcm_substream {
         struct snd_pcm_group *group;            /* pointer to current group */
         /* -- assigned files -- */
         void *file;
-        struct file *ffile;
+        int ref_count;
+        unsigned int f_flags;
         void (*pcm_release)(struct snd_pcm_substream *);
 #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE)
         /* -- OSS things -- */
@@ -387,7 +388,7 @@ struct snd_pcm_substream {
         unsigned int hw_opened: 1;
 };
 
-#define SUBSTREAM_BUSY(substream) ((substream)->file != NULL)
+#define SUBSTREAM_BUSY(substream) ((substream)->ref_count > 0)
 
 
 struct snd_pcm_str {
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index d8b7416ee00..9803a6ce3d4 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -1331,7 +1331,7 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
                                 if (runtime->oss.period_ptr == 0 ||
                                     runtime->oss.period_ptr == runtime->oss.buffer_used)
                                         runtime->oss.buffer_used = 0;
-                                else if ((substream->ffile->f_flags & O_NONBLOCK) != 0)
+                                else if ((substream->f_flags & O_NONBLOCK) != 0)
                                         return xfer > 0 ? xfer : -EAGAIN;
                         }
                 } else {
@@ -1344,7 +1344,7 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
                         buf += tmp;
                         bytes -= tmp;
                         xfer += tmp;
-                        if ((substream->ffile->f_flags & O_NONBLOCK) != 0 &&
+                        if ((substream->f_flags & O_NONBLOCK) != 0 &&
                             tmp != runtime->oss.period_bytes)
                                 break;
                 }
@@ -1582,10 +1582,10 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
                  * finish sync: drain the buffer
                  */
               __direct:
-                saved_f_flags = substream->ffile->f_flags;
-                substream->ffile->f_flags &= ~O_NONBLOCK;
+                saved_f_flags = substream->f_flags;
+                substream->f_flags &= ~O_NONBLOCK;
                 err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
-                substream->ffile->f_flags = saved_f_flags;
+                substream->f_flags = saved_f_flags;
                 if (err < 0)
                         return err;
                 runtime->oss.prepare = 1;
@@ -2164,9 +2164,9 @@ static void snd_pcm_oss_init_substream(struct snd_pcm_substream *substream,
         substream->oss.oss = 1;
         substream->oss.setup = *setup;
         if (setup->nonblock)
-                substream->ffile->f_flags |= O_NONBLOCK;
+                substream->f_flags |= O_NONBLOCK;
         else if (setup->block)
-                substream->ffile->f_flags &= ~O_NONBLOCK;
+                substream->f_flags &= ~O_NONBLOCK;
         runtime = substream->runtime;
         runtime->oss.params = 1;
         runtime->oss.trigger = 1;
@@ -2223,6 +2223,7 @@ static int snd_pcm_oss_open_file(struct file *file,
             (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX))
                 f_mode = FMODE_WRITE;
 
+        file->f_flags &= ~O_APPEND;
         for (idx = 0; idx < 2; idx++) {
                 if (setup[idx].disable)
                         continue;
@@ -2540,6 +2541,7 @@ static ssize_t snd_pcm_oss_read(struct file *file, char __user *buf, size_t coun
         substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
         if (substream == NULL)
                 return -ENXIO;
+        substream->f_flags = file->f_flags & O_NONBLOCK;
 #ifndef OSS_DEBUG
         return snd_pcm_oss_read1(substream, buf, count);
 #else
@@ -2561,6 +2563,7 @@ static ssize_t snd_pcm_oss_write(struct file *file, const char __user *buf, size
         substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
         if (substream == NULL)
                 return -ENXIO;
+        substream->f_flags = file->f_flags & O_NONBLOCK;
         result = snd_pcm_oss_write1(substream, buf, count);
 #ifdef OSS_DEBUG
         printk("pcm_oss: write %li bytes (wrote %li bytes)\n", (long)count, (long)result);
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 4f5204175d3..8136be2e606 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -829,6 +829,26 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
                 return -EINVAL;
         }
 
+        if (file->f_flags & O_APPEND) {
+                if (prefer_subdevice < 0) {
+                        if (pstr->substream_count > 1)
+                                return -EINVAL; /* must be unique */
+                        substream = pstr->substream;
+                } else {
+                        for (substream = pstr->substream; substream;
+                             substream = substream->next)
+                                if (substream->number == prefer_subdevice)
+                                        break;
+                }
+                if (! substream)
+                        return -ENODEV;
+                if (! SUBSTREAM_BUSY(substream))
+                        return -EBADFD;
+                substream->ref_count++;
+                *rsubstream = substream;
+                return 0;
+        }
+
         if (prefer_subdevice >= 0) {
                 for (substream = pstr->substream; substream; substream = substream->next)
                         if (!SUBSTREAM_BUSY(substream) && substream->number == prefer_subdevice)
@@ -873,7 +893,8 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 
         substream->runtime = runtime;
         substream->private_data = pcm->private_data;
-        substream->ffile = file;
+        substream->ref_count = 1;
+        substream->f_flags = file->f_flags;
         pstr->substream_opened++;
         *rsubstream = substream;
         return 0;
@@ -882,7 +903,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
 {
         struct snd_pcm_runtime *runtime;
-        substream->file = NULL;
+
         runtime = substream->runtime;
         snd_assert(runtime != NULL, return);
         if (runtime->private_free != NULL)
diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index e5133033de5..2b8aab6fd6c 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -497,9 +497,9 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l
         case SNDRV_PCM_IOCTL_LINK:
         case SNDRV_PCM_IOCTL_UNLINK:
                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
-                        return snd_pcm_playback_ioctl1(substream, cmd, argp);
+                        return snd_pcm_playback_ioctl1(file, substream, cmd, argp);
                 else
-                        return snd_pcm_capture_ioctl1(substream, cmd, argp);
+                        return snd_pcm_capture_ioctl1(file, substream, cmd, argp);
         case SNDRV_PCM_IOCTL_HW_REFINE32:
                 return snd_pcm_ioctl_hw_params_compat(substream, 1, argp);
         case SNDRV_PCM_IOCTL_HW_PARAMS32:
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index a21aa0050e4..0bb142a2853 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1782,7 +1782,7 @@ snd_pcm_sframes_t snd_pcm_lib_write(struct snd_pcm_substream *substream, const v
         if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
                 return -EBADFD;
 
-        nonblock = !!(substream->ffile->f_flags & O_NONBLOCK);
+        nonblock = !!(substream->f_flags & O_NONBLOCK);
 
         if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
             runtime->channels > 1)
@@ -1847,7 +1847,7 @@ snd_pcm_sframes_t snd_pcm_lib_writev(struct snd_pcm_substream *substream,
         if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
                 return -EBADFD;
 
-        nonblock = !!(substream->ffile->f_flags & O_NONBLOCK);
+        nonblock = !!(substream->f_flags & O_NONBLOCK);
 
         if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
                 return -EINVAL;
@@ -2059,7 +2059,7 @@ snd_pcm_sframes_t snd_pcm_lib_read(struct snd_pcm_substream *substream, void __u
         if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
                 return -EBADFD;
 
-        nonblock = !!(substream->ffile->f_flags & O_NONBLOCK);
+        nonblock = !!(substream->f_flags & O_NONBLOCK);
         if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED)
                 return -EINVAL;
         return snd_pcm_lib_read1(substream, (unsigned long)buf, size, nonblock, snd_pcm_lib_read_transfer);
@@ -2118,7 +2118,7 @@ snd_pcm_sframes_t snd_pcm_lib_readv(struct snd_pcm_substream *substream,
         if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
                 return -EBADFD;
 
-        nonblock = !!(substream->ffile->f_flags & O_NONBLOCK);
+        nonblock = !!(substream->f_flags & O_NONBLOCK);
         if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
                 return -EINVAL;
         return snd_pcm_lib_read1(substream, (unsigned long)bufs, frames, nonblock, snd_pcm_lib_readv_transfer);
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 7b5729c4b21..36d6765618a 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1284,13 +1284,16 @@ static int snd_pcm_reset(struct snd_pcm_substream *substream)
 /*
  * prepare ioctl
  */
-static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream, int state)
+/* we use the second argument for updating f_flags */
+static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream,
+                               int f_flags)
 {
         struct snd_pcm_runtime *runtime = substream->runtime;
         if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
                 return -EBADFD;
         if (snd_pcm_running(substream))
                 return -EBUSY;
+        substream->f_flags = f_flags;
         return 0;
 }
 
@@ -1319,17 +1322,26 @@ static struct action_ops snd_pcm_action_prepare = {
 /**
  * snd_pcm_prepare
  * @substream: the PCM substream instance
+ * @file: file to refer f_flags
  *
  * Prepare the PCM substream to be triggerable.
  */
-static int snd_pcm_prepare(struct snd_pcm_substream *substream)
+static int snd_pcm_prepare(struct snd_pcm_substream *substream,
+                           struct file *file)
 {
         int res;
         struct snd_card *card = substream->pcm->card;
+        int f_flags;
+
+        if (file)
+                f_flags = file->f_flags;
+        else
+                f_flags = substream->f_flags;
 
         snd_power_lock(card);
         if ((res = snd_power_wait(card, SNDRV_CTL_POWER_D0)) >= 0)
-                res = snd_pcm_action_nonatomic(&snd_pcm_action_prepare, substream, 0);
+                res = snd_pcm_action_nonatomic(&snd_pcm_action_prepare,
+                                               substream, f_flags);
         snd_power_unlock(card);
         return res;
 }
@@ -1340,7 +1352,7 @@ static int snd_pcm_prepare(struct snd_pcm_substream *substream)
 
 static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream, int state)
 {
-        if (substream->ffile->f_flags & O_NONBLOCK)
+        if (substream->f_flags & O_NONBLOCK)
                 return -EAGAIN;
         substream->runtime->trigger_master = substream;
         return 0;
@@ -2015,6 +2027,10 @@ static void pcm_release_private(struct snd_pcm_substream *substream)
 
 void snd_pcm_release_substream(struct snd_pcm_substream *substream)
 {
+        substream->ref_count--;
+        if (substream->ref_count > 0)
+                return;
+
         snd_pcm_drop(substream);
         if (substream->hw_opened) {
                 if (substream->ops->hw_free != NULL)
@@ -2041,6 +2057,11 @@ int snd_pcm_open_substream(struct snd_pcm *pcm, int stream,
         err = snd_pcm_attach_substream(pcm, stream, file, &substream);
         if (err < 0)
                 return err;
+        if (substream->ref_count > 1) {
+                *rsubstream = substream;
+                return 0;
+        }
+
         substream->no_mmap_ctrl = 0;
         err = snd_pcm_hw_constraints_init(substream);
         if (err < 0) {
@@ -2086,17 +2107,20 @@ static int snd_pcm_open_file(struct file *file,
         if (err < 0)
                 return err;
 
-        pcm_file = kzalloc(sizeof(*pcm_file), GFP_KERNEL);
-        if (pcm_file == NULL) {
-                snd_pcm_release_substream(substream);
-                return -ENOMEM;
+        if (substream->ref_count > 1)
+                pcm_file = substream->file;
+        else {
+                pcm_file = kzalloc(sizeof(*pcm_file), GFP_KERNEL);
+                if (pcm_file == NULL) {
+                        snd_pcm_release_substream(substream);
+                        return -ENOMEM;
+                }
+                str = substream->pstr;
+                substream->file = pcm_file;
+                substream->pcm_release = pcm_release_private;
+                pcm_file->substream = substream;
+                snd_pcm_add_file(str, pcm_file);
         }
-        str = substream->pstr;
-        substream->file = pcm_file;
-        substream->pcm_release = pcm_release_private;
-        pcm_file->substream = substream;
-        snd_pcm_add_file(str, pcm_file);
-
         file->private_data = pcm_file;
         *rpcm_file = pcm_file;
         return 0;
@@ -2506,7 +2530,8 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
         return 0;
 }
                 
-static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_common_ioctl1(struct file *file,
+                                 struct snd_pcm_substream *substream,
                                  unsigned int cmd, void __user *arg)
 {
         snd_assert(substream != NULL, return -ENXIO);
@@ -2531,7 +2556,7 @@ static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
         case SNDRV_PCM_IOCTL_CHANNEL_INFO:
                 return snd_pcm_channel_info_user(substream, arg);
         case SNDRV_PCM_IOCTL_PREPARE:
-                return snd_pcm_prepare(substream);
+                return snd_pcm_prepare(substream, file);
         case SNDRV_PCM_IOCTL_RESET:
                 return snd_pcm_reset(substream);
         case SNDRV_PCM_IOCTL_START:
@@ -2573,7 +2598,8 @@ static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
         return -ENOTTY;
 }
 
-static int snd_pcm_playback_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_playback_ioctl1(struct file *file,
+                                   struct snd_pcm_substream *substream,
                                    unsigned int cmd, void __user *arg)
 {
         snd_assert(substream != NULL, return -ENXIO);
@@ -2649,10 +2675,11 @@ static int snd_pcm_playback_ioctl1(struct snd_pcm_substream *substream,
                 return result < 0 ? result : 0;
         }
         }
-        return snd_pcm_common_ioctl1(substream, cmd, arg);
+        return snd_pcm_common_ioctl1(file, substream, cmd, arg);
 }
 
-static int snd_pcm_capture_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_capture_ioctl1(struct file *file,
+                                  struct snd_pcm_substream *substream,
                                   unsigned int cmd, void __user *arg)
 {
         snd_assert(substream != NULL, return -ENXIO);
@@ -2728,7 +2755,7 @@ static int snd_pcm_capture_ioctl1(struct snd_pcm_substream *substream,
                 return result < 0 ? result : 0;
         }
         }
-        return snd_pcm_common_ioctl1(substream, cmd, arg);
+        return snd_pcm_common_ioctl1(file, substream, cmd, arg);
 }
 
 static long snd_pcm_playback_ioctl(struct file *file, unsigned int cmd,
@@ -2741,7 +2768,8 @@ static long snd_pcm_playback_ioctl(struct file *file, unsigned int cmd,
         if (((cmd >> 8) & 0xff) != 'A')
                 return -ENOTTY;
 
-        return snd_pcm_playback_ioctl1(pcm_file->substream, cmd, (void __user *)arg);
+        return snd_pcm_playback_ioctl1(file, pcm_file->substream, cmd,
+                                       (void __user *)arg);
 }
 
 static long snd_pcm_capture_ioctl(struct file *file, unsigned int cmd,
@@ -2754,7 +2782,8 @@ static long snd_pcm_capture_ioctl(struct file *file, unsigned int cmd,
         if (((cmd >> 8) & 0xff) != 'A')
                 return -ENOTTY;
 
-        return snd_pcm_capture_ioctl1(pcm_file->substream, cmd, (void __user *)arg);
+        return snd_pcm_capture_ioctl1(file, pcm_file->substream, cmd,
+                                      (void __user *)arg);
 }
 
 int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
@@ -2766,12 +2795,12 @@ int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
         fs = snd_enter_user();
         switch (substream->stream) {
         case SNDRV_PCM_STREAM_PLAYBACK:
-                result = snd_pcm_playback_ioctl1(substream,
-                                                 cmd, (void __user *)arg);
+                result = snd_pcm_playback_ioctl1(NULL, substream, cmd,
+                                                 (void __user *)arg);
                 break;
         case SNDRV_PCM_STREAM_CAPTURE:
-                result = snd_pcm_capture_ioctl1(substream,
-                                                cmd, (void __user *)arg);
+                result = snd_pcm_capture_ioctl1(NULL, substream, cmd,
+                                                (void __user *)arg);
                 break;
         default:
                 result = -EINVAL;
diff --git a/sound/usb/usx2y/usx2yhwdeppcm.c b/sound/usb/usx2y/usx2yhwdeppcm.c
index fe67a92e2a1..88b72b52590 100644
--- a/sound/usb/usx2y/usx2yhwdeppcm.c
+++ b/sound/usb/usx2y/usx2yhwdeppcm.c
@@ -632,7 +632,7 @@ static int usX2Y_pcms_lock_check(struct snd_card *card)
                 for (s = 0; s < 2; ++s) {
                         struct snd_pcm_substream *substream;
                         substream = pcm->streams[s].substream;
-                        if (substream && substream->ffile != NULL)
+                        if (SUBSTREAM_BUSY(substream))
                                 err = -EBUSY;
                 }
         }