Fix up sound driver proc-reading interfaces.

The old ones were not only hard to use, they were in fact
impossible or a low-level sound driver to get right, since
the core sound code didn't even export all the necessary
information.

Add the file offset to the /proc read interfaces, and make
them simpler to use. The core now does a offset updates, and
sanity-checks the values so that the low-level drivers don't
need to worry.

Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl

@@ -5182,7 +5182,7 @@ struct _snd_pcm_runtime {
       The callback is much more complicated than the text-file
       version. You need to use a low-level i/o functions such as
       <function>copy_from/to_user()</function> to transfer the
-      data. Also, you have to keep tracking the file position, too. 
+      data.
 
       <informalexample>
         <programlisting>
@@ -5190,14 +5190,15 @@ struct _snd_pcm_runtime {
   static long my_file_io_read(snd_info_entry_t *entry,
                               void *file_private_data,
                               struct file *file,
-                              char *buf, long count)
+                              char *buf,
+                              unsigned long count,
+                              unsigned long pos)
   {
           long size = count;
-          if (file->f_pos + size > local_max_size)
-                  size = local_max_size - file->f_pos;
-          if (copy_to_user(buf, local_data + file->f_pos, size))
+          if (pos + size > local_max_size)
+                  size = local_max_size - pos;
+          if (copy_to_user(buf, local_data + pos, size))
                   return -EFAULT;
-          file->f_pos += size;
           return size;
   }
 ]]>

include/sound/info.h

@@ -54,9 +54,11 @@ struct snd_info_entry_ops {
 	int (*release) (snd_info_entry_t * entry,
 			unsigned short mode, void *file_private_data);
 	long (*read) (snd_info_entry_t *entry, void *file_private_data,
-		      struct file * file, char __user *buf, long count);
+		      struct file * file, char __user *buf,
+		      unsigned long count, unsigned long pos);
 	long (*write) (snd_info_entry_t *entry, void *file_private_data,
-		       struct file * file, const char __user *buf, long count);
+		       struct file * file, const char __user *buf,
+		       unsigned long count, unsigned long pos);
 	long long (*llseek) (snd_info_entry_t *entry, void *file_private_data,
 			    struct file * file, long long offset, int orig);
 	unsigned int (*poll) (snd_info_entry_t *entry, void *file_private_data,

sound/core/info.c

@@ -181,30 +181,37 @@ static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
 	struct snd_info_entry *entry;
 	snd_info_buffer_t *buf;
 	size_t size = 0;
+	loff_t pos;
 
 	data = snd_magic_cast(snd_info_private_data_t, file->private_data, return -ENXIO);
 	snd_assert(data != NULL, return -ENXIO);
+	pos = *offset;
+	if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
+		return -EIO;
+	if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
+		return -EIO;
 	entry = data->entry;
 	switch (entry->content) {
 	case SNDRV_INFO_CONTENT_TEXT:
 		buf = data->rbuffer;
 		if (buf == NULL)
 			return -EIO;
-		if (file->f_pos >= (long)buf->size)
+		if (pos >= buf->size)
 			return 0;
-		size = buf->size - file->f_pos;
+		size = buf->size - pos;
 		size = min(count, size);
-		if (copy_to_user(buffer, buf->buffer + file->f_pos, size))
+		if (copy_to_user(buffer, buf->buffer + pos, size))
 			return -EFAULT;
-		file->f_pos += size;
 		break;
 	case SNDRV_INFO_CONTENT_DATA:
 		if (entry->c.ops->read)
-			return entry->c.ops->read(entry,
+			size = entry->c.ops->read(entry,
 						  data->file_private_data,
-						  file, buffer, count);
+						  file, buffer, count, pos);
 		break;
 	}
+	if ((ssize_t) size > 0)
+		*offset = pos + size;
 	return size;
 }
 
@@ -215,34 +222,39 @@ static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer
 	struct snd_info_entry *entry;
 	snd_info_buffer_t *buf;
 	size_t size = 0;
+	loff_t pos;
 
 	data = snd_magic_cast(snd_info_private_data_t, file->private_data, return -ENXIO);
 	snd_assert(data != NULL, return -ENXIO);
 	entry = data->entry;
+	pos = *offset;
+	if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
+		return -EIO;
+	if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
+		return -EIO;
 	switch (entry->content) {
 	case SNDRV_INFO_CONTENT_TEXT:
 		buf = data->wbuffer;
 		if (buf == NULL)
 			return -EIO;
-		if (file->f_pos < 0)
-			return -EINVAL;
-		if (file->f_pos >= (long)buf->len)
+		if (pos >= buf->len)
 			return -ENOMEM;
-		size = buf->len - file->f_pos;
+		size = buf->len - pos;
 		size = min(count, size);
-		if (copy_from_user(buf->buffer + file->f_pos, buffer, size))
+		if (copy_from_user(buf->buffer + pos, buffer, size))
 			return -EFAULT;
-		if ((long)buf->size < file->f_pos + size)
-			buf->size = file->f_pos + size;
-		file->f_pos += size;
+		if ((long)buf->size < pos + size)
+			buf->size = pos + size;
 		break;
 	case SNDRV_INFO_CONTENT_DATA:
 		if (entry->c.ops->write)
-			return entry->c.ops->write(entry,
+			size = entry->c.ops->write(entry,
 						   data->file_private_data,
-						   file, buffer, count);
+						   file, buffer, count, pos);
 		break;
 	}
+	if ((ssize_t) size > 0)
+		*offset = pos + size;
 	return size;
 }
 

sound/drivers/opl4/opl4_proc.c

@@ -50,41 +50,42 @@ static int snd_opl4_mem_proc_release(snd_info_entry_t *entry,
 }
 
 static long snd_opl4_mem_proc_read(snd_info_entry_t *entry, void *file_private_data,
-				   struct file *file, char __user *_buf, long count)
+				   struct file *file, char __user *_buf,
+				   unsigned long count, unsigned long pos)
 {
 	opl4_t *opl4 = snd_magic_cast(opl4_t, entry->private_data, return -ENXIO);
 	long size;
 	char* buf;
 
 	size = count;
-	if (file->f_pos + size > entry->size)
-		size = entry->size - file->f_pos;
+	if (pos + size > entry->size)
+		size = entry->size - pos;
 	if (size > 0) {
 		buf = vmalloc(size);
 		if (!buf)
 			return -ENOMEM;
-		snd_opl4_read_memory(opl4, buf, file->f_pos, size);
+		snd_opl4_read_memory(opl4, buf, pos, size);
 		if (copy_to_user(_buf, buf, size)) {
 			vfree(buf);
 			return -EFAULT;
 		}
 		vfree(buf);
-		file->f_pos += size;
 		return size;
 	}
 	return 0;
 }
 
 static long snd_opl4_mem_proc_write(snd_info_entry_t *entry, void *file_private_data,
-				    struct file *file, const char __user *_buf, long count)
+				    struct file *file, const char __user *_buf,
+				    unsigned long count, unsigned long pos)
 {
 	opl4_t *opl4 = snd_magic_cast(opl4_t, entry->private_data, return -ENXIO);
 	long size;
 	char *buf;
 
 	size = count;
-	if (file->f_pos + size > entry->size)
-		size = entry->size - file->f_pos;
+	if (pos + size > entry->size)
+		size = entry->size - pos;
 	if (size > 0) {
 		buf = vmalloc(size);
 		if (!buf)
@@ -93,9 +94,8 @@ static long snd_opl4_mem_proc_write(snd_info_entry_t *entry, void *file_private_
 			vfree(buf);
 			return -EFAULT;
 		}
-		snd_opl4_write_memory(opl4, buf, file->f_pos, size);
+		snd_opl4_write_memory(opl4, buf, pos, size);
 		vfree(buf);
-		file->f_pos += size;
 		return size;
 	}
 	return 0;

sound/isa/gus/gus_mem_proc.c

@@ -33,7 +33,8 @@ typedef struct gus_proc_private {
 } gus_proc_private_t;
 
 static long snd_gf1_mem_proc_dump(snd_info_entry_t *entry, void *file_private_data,
-			          struct file *file, char __user *buf, long count)
+			          struct file *file, char __user *buf,
+			          unsigned long count, unsigned long pos)
 {
 	long size;
 	gus_proc_private_t *priv = snd_magic_cast(gus_proc_private_t, entry->private_data, return -ENXIO);
@@ -41,12 +42,11 @@ static long snd_gf1_mem_proc_dump(snd_info_entry_t *entry, void *file_private_da
 	int err;
 
 	size = count;
-	if (file->f_pos + size > priv->size)
-		size = (long)priv->size - file->f_pos;
+	if (pos + size > priv->size)
+		size = (long)priv->size - pos;
 	if (size > 0) {
-		if ((err = snd_gus_dram_read(gus, buf, file->f_pos, size, priv->rom)) < 0)
+		if ((err = snd_gus_dram_read(gus, buf, pos, size, priv->rom)) < 0)
 			return err;
-		file->f_pos += size;
 		return size;
 	}
 	return 0;

sound/pci/cs4281.c

@@ -1185,35 +1185,35 @@ static void snd_cs4281_proc_read(snd_info_entry_t *entry,
 }
 
 static long snd_cs4281_BA0_read(snd_info_entry_t *entry, void *file_private_data,
-				struct file *file, char __user *buf, long count)
+				struct file *file, char __user *buf,
+				unsigned long count, unsigned long pos)
 {
 	long size;
 	cs4281_t *chip = snd_magic_cast(cs4281_t, entry->private_data, return -ENXIO);
 	
 	size = count;
-	if (file->f_pos + size > CS4281_BA0_SIZE)
-		size = (long)CS4281_BA0_SIZE - file->f_pos;
+	if (pos + size > CS4281_BA0_SIZE)
+		size = (long)CS4281_BA0_SIZE - pos;
 	if (size > 0) {
-		if (copy_to_user_fromio(buf, chip->ba0 + file->f_pos, size))
+		if (copy_to_user_fromio(buf, chip->ba0 + pos, size))
 			return -EFAULT;
-		file->f_pos += size;
 	}
 	return size;
 }
 
 static long snd_cs4281_BA1_read(snd_info_entry_t *entry, void *file_private_data,
-				struct file *file, char __user *buf, long count)
+				struct file *file, char __user *buf,
+				unsigned long count, unsigned long pos)
 {
 	long size;
 	cs4281_t *chip = snd_magic_cast(cs4281_t, entry->private_data, return -ENXIO);
 	
 	size = count;
-	if (file->f_pos + size > CS4281_BA1_SIZE)
-		size = (long)CS4281_BA1_SIZE - file->f_pos;
+	if (pos + size > CS4281_BA1_SIZE)
+		size = (long)CS4281_BA1_SIZE - pos;
 	if (size > 0) {
-		if (copy_to_user_fromio(buf, chip->ba1 + file->f_pos, size))
+		if (copy_to_user_fromio(buf, chip->ba1 + pos, size))
 			return -EFAULT;
-		file->f_pos += size;
 	}
 	return size;
 }

sound/pci/cs46xx/cs46xx_lib.c

@@ -2866,18 +2866,18 @@ void __devinit snd_cs46xx_gameport(cs46xx_t *chip)
  */
 
 static long snd_cs46xx_io_read(snd_info_entry_t *entry, void *file_private_data,
-			       struct file *file, char __user *buf, long count)
+			       struct file *file, char __user *buf,
+			       unsigned long count, unsigned long pos)
 {
 	long size;
 	snd_cs46xx_region_t *region = (snd_cs46xx_region_t *)entry->private_data;
 	
 	size = count;
-	if (file->f_pos + (size_t)size > region->size)
-		size = region->size - file->f_pos;
+	if (pos + (size_t)size > region->size)
+		size = region->size - pos;
 	if (size > 0) {
-		if (copy_to_user_fromio(buf, region->remap_addr + file->f_pos, size))
+		if (copy_to_user_fromio(buf, region->remap_addr + pos, size))
 			return -EFAULT;
-		file->f_pos += size;
 	}
 	return size;
 }

sound/pci/emu10k1/emuproc.c

@@ -191,7 +191,8 @@ static void snd_emu10k1_proc_acode_read(snd_info_entry_t *entry,
 #define TOTAL_SIZE_CODE		(0x200*8)
 
 static long snd_emu10k1_fx8010_read(snd_info_entry_t *entry, void *file_private_data,
-				    struct file *file, char __user *buf, long count)
+				    struct file *file, char __user *buf,
+				    unsigned long count, unsigned long pos)
 {
 	long size;
 	emu10k1_t *emu = snd_magic_cast(emu10k1_t, entry->private_data, return -ENXIO);
@@ -209,21 +210,20 @@ static long snd_emu10k1_fx8010_read(snd_info_entry_t *entry, void *file_private_
 		offset = emu->audigy ? A_FXGPREGBASE : FXGPREGBASE;
 	}
 	size = count;
-	if (file->f_pos + size > entry->size)
-		size = (long)entry->size - file->f_pos;
+	if (pos + size > entry->size)
+		size = (long)entry->size - pos;
 	if (size > 0) {
 		unsigned int *tmp;
 		long res;
 		unsigned int idx;
 		if ((tmp = kmalloc(size + 8, GFP_KERNEL)) == NULL)
 			return -ENOMEM;
-		for (idx = 0; idx < ((file->f_pos & 3) + size + 3) >> 2; idx++)
-			tmp[idx] = snd_emu10k1_ptr_read(emu, offset + idx + (file->f_pos >> 2), 0);
-		if (copy_to_user(buf, ((char *)tmp) + (file->f_pos & 3), size))
+		for (idx = 0; idx < ((pos & 3) + size + 3) >> 2; idx++)
+			tmp[idx] = snd_emu10k1_ptr_read(emu, offset + idx + (pos >> 2), 0);
+		if (copy_to_user(buf, ((char *)tmp) + (pos & 3), size))
 			res = -EFAULT;
 		else {
 			res = size;
-			file->f_pos += size;
 		}
 		kfree(tmp);
 		return res;

sound/pci/mixart/mixart.c

@@ -1154,18 +1154,18 @@ static long long snd_mixart_BA1_llseek(snd_info_entry_t *entry,
   mixart_BA0 proc interface for BAR 0 - read callback
  */
 static long snd_mixart_BA0_read(snd_info_entry_t *entry, void *file_private_data,
-				struct file *file, char __user *buf, long count)
+				struct file *file, char __user *buf,
+				unsigned long count, unsigned long pos)
 {
 	mixart_mgr_t *mgr = snd_magic_cast(mixart_mgr_t, entry->private_data, return -ENXIO);
 
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
 	if(count <= 0)
 		return 0;
-	if(file->f_pos + count > MIXART_BA0_SIZE)
-		count = (long)(MIXART_BA0_SIZE - file->f_pos);
-	if(copy_to_user_fromio(buf, MIXART_MEM( mgr, file->f_pos ), count))
+	if(pos + count > MIXART_BA0_SIZE)
+		count = (long)(MIXART_BA0_SIZE - pos);
+	if(copy_to_user_fromio(buf, MIXART_MEM( mgr, pos ), count))
 		return -EFAULT;
-	file->f_pos += count;
 	return count;
 }
 
@@ -1173,18 +1173,18 @@ static long snd_mixart_BA0_read(snd_info_entry_t *entry, void *file_private_data
   mixart_BA1 proc interface for BAR 1 - read callback
  */
 static long snd_mixart_BA1_read(snd_info_entry_t *entry, void *file_private_data,
-				struct file *file, char __user *buf, long count)
+				struct file *file, char __user *buf,
+				unsigned long count, unsigned long pos)
 {
 	mixart_mgr_t *mgr = snd_magic_cast(mixart_mgr_t, entry->private_data, return -ENXIO);
 
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
 	if(count <= 0)
 		return 0;
-	if(file->f_pos + count > MIXART_BA1_SIZE)
-		count = (long)(MIXART_BA1_SIZE - file->f_pos);
-	if(copy_to_user_fromio(buf, MIXART_REG( mgr, file->f_pos ), count))
+	if(pos + count > MIXART_BA1_SIZE)
+		count = (long)(MIXART_BA1_SIZE - pos);
+	if(copy_to_user_fromio(buf, MIXART_REG( mgr, pos ), count))
 		return -EFAULT;
-	file->f_pos += count;
 	return count;
 }