[PATCH RFC 22/23] ALSA: info: let procfs copy out reads of data entries

@@ -3679,9 +3679,10 @@ For raw data, ``size`` field must be set properly. This specifies
 the maximum size of the proc file access.
 
 The read/write callbacks of raw mode are more direct than the text mode.
-You need to use a low-level I/O functions such as
-:c:func:`copy_from_user()` and :c:func:`copy_to_user()` to transfer the
-data::
+They get a kernel buffer that procfs copies to or from userspace, so they
+just copy the data. The buffer holds at most a page and isn't zeroed, so
+a read callback must return exactly what it copied into it; a larger
+read comes back for the rest::
 
   static ssize_t my_file_io_read(struct snd_info_entry *entry,
                               void *file_private_data,

@@ -3690,8 +3691,7 @@ data::
                               size_t count,
                               loff_t pos)
   {
-          if (copy_to_user(buf, local_data + pos, count))
-                  return -EFAULT;
+          memcpy(buf, local_data + pos, count);
           return count;
   }
 

@@ -594,7 +594,7 @@ void snd_gf1_uart_resume(struct snd_gus_card *gus);
 /* gus_dram.c */
 int snd_gus_dram_write(struct snd_gus_card *gus, char __user *ptr,
 		       unsigned int addr, unsigned int size);
-int snd_gus_dram_read(struct snd_gus_card *gus, char __user *ptr,
+int snd_gus_dram_read(struct snd_gus_card *gus, char *ptr,
 		      unsigned int addr, unsigned int size, int rom);
 
 /* gus_timer.c */

@@ -39,7 +39,7 @@ struct snd_info_entry_ops {
 	int (*release)(struct snd_info_entry *entry,
 		       unsigned short mode, void *file_private_data);
 	ssize_t (*read)(struct snd_info_entry *entry, void *file_private_data,
-			struct file *file, char __user *buf,
+			struct file *file, char *buf,
 			size_t count, loff_t pos);
 	ssize_t (*write)(struct snd_info_entry *entry, void *file_private_data,
 			 struct file *file, const char *buf,

@@ -138,7 +138,7 @@ static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
 	return offset;
 }
 
-static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
+static ssize_t snd_info_entry_read(struct file *file, char *buffer,
 				   size_t count, loff_t * offset)
 {
 	struct snd_info_private_data *data = file->private_data;

@@ -277,9 +277,9 @@ static int snd_info_entry_release(struct inode *inode, struct file *file)
 
 static const struct proc_ops snd_info_entry_operations =
 {
-	.proc_flags	= PROC_ENTRY_SHORT_WRITES,
+	.proc_flags	= PROC_ENTRY_SHORT_WRITES | PROC_ENTRY_FULL_READS,
 	.proc_lseek	= snd_info_entry_llseek,
-	.proc_read	= snd_info_entry_read,
+	.proc_read_buf	= snd_info_entry_read,
 	.proc_write_buf	= snd_info_entry_write,
 	.proc_write_size = PAGE_SIZE,
 	.proc_poll	= snd_info_entry_poll,

@@ -5,7 +5,6 @@
  */
 
 #include "opl4_local.h"
-#include <linux/vmalloc.h>
 #include <linux/export.h>
 #include <sound/info.h>
 

@@ -33,21 +32,12 @@ static int snd_opl4_mem_proc_release(struct snd_info_entry *entry,
 
 static ssize_t snd_opl4_mem_proc_read(struct snd_info_entry *entry,
 				      void *file_private_data,
-				      struct file *file, char __user *_buf,
+				      struct file *file, char *buf,
 				      size_t count, loff_t pos)
 {
 	struct snd_opl4 *opl4 = entry->private_data;
-	char* buf;
 
-	buf = vmalloc(count);
-	if (!buf)
-		return -ENOMEM;
 	snd_opl4_read_memory(opl4, buf, pos, count);
-	if (copy_to_user(_buf, buf, count)) {
-		vfree(buf);
-		return -EFAULT;
-	}
-	vfree(buf);
 	return count;
 }
 

@@ -45,7 +45,7 @@ int snd_gus_dram_write(struct snd_gus_card *gus, char __user *buffer,
 	return snd_gus_dram_poke(gus, buffer, address, size);
 }
 
-static int snd_gus_dram_peek(struct snd_gus_card *gus, char __user *_buffer,
+static int snd_gus_dram_peek(struct snd_gus_card *gus, char *_buffer,
 			     unsigned int address, unsigned int size,
 			     int rom)
 {

@@ -67,15 +67,14 @@ static int snd_gus_dram_peek(struct snd_gus_card *gus, char __user *_buffer,
 			while (size2--)
 				*pbuffer++ = snd_gf1_peek(gus, address++);
 		}
-		if (copy_to_user(_buffer, buffer, size1))
-			return -EFAULT;
+		memcpy(_buffer, buffer, size1);
 		size -= size1;
 		_buffer += size1;
 	}
 	return 0;
 }
 
-int snd_gus_dram_read(struct snd_gus_card *gus, char __user *buffer,
+int snd_gus_dram_read(struct snd_gus_card *gus, char *buffer,
 		      unsigned int address, unsigned int size,
 		      int rom)
 {

@@ -18,7 +18,7 @@ struct gus_proc_private {
 
 static ssize_t snd_gf1_mem_proc_dump(struct snd_info_entry *entry,
 				     void *file_private_data,
-				     struct file *file, char __user *buf,
+				     struct file *file, char *buf,
 				     size_t count, loff_t pos)
 {
 	struct gus_proc_private *priv = entry->private_data;

@@ -1104,25 +1104,23 @@ static void snd_cs4281_proc_read(struct snd_info_entry *entry,
 
 static ssize_t snd_cs4281_BA0_read(struct snd_info_entry *entry,
 				   void *file_private_data,
-				   struct file *file, char __user *buf,
+				   struct file *file, char *buf,
 				   size_t count, loff_t pos)
 {
 	struct cs4281 *chip = entry->private_data;
 	
-	if (copy_to_user_fromio(buf, chip->ba0 + pos, count))
-		return -EFAULT;
+	memcpy_fromio(buf, chip->ba0 + pos, count);
 	return count;
 }
 
 static ssize_t snd_cs4281_BA1_read(struct snd_info_entry *entry,
 				   void *file_private_data,
-				   struct file *file, char __user *buf,
+				   struct file *file, char *buf,
 				   size_t count, loff_t pos)
 {
 	struct cs4281 *chip = entry->private_data;
 	
-	if (copy_to_user_fromio(buf, chip->ba1 + pos, count))
-		return -EFAULT;
+	memcpy_fromio(buf, chip->ba1 + pos, count);
 	return count;
 }
 

@@ -2741,13 +2741,12 @@ static inline void snd_cs46xx_remove_gameport(struct snd_cs46xx *chip) { }
 
 static ssize_t snd_cs46xx_io_read(struct snd_info_entry *entry,
 				  void *file_private_data,
-				  struct file *file, char __user *buf,
+				  struct file *file, char *buf,
 				  size_t count, loff_t pos)
 {
 	struct snd_cs46xx_region *region = entry->private_data;
 	
-	if (copy_to_user_fromio(buf, region->remap_addr + pos, count))
-		return -EFAULT;
+	memcpy_fromio(buf, region->remap_addr + pos, count);
 	return count;
 }
 

@@ -382,7 +382,7 @@ static void snd_emu10k1_proc_acode_read(struct snd_info_entry *entry,
 
 static ssize_t snd_emu10k1_fx8010_read(struct snd_info_entry *entry,
 				       void *file_private_data,
-				       struct file *file, char __user *buf,
+				       struct file *file, char *buf,
 				       size_t count, loff_t pos)
 {
 	struct snd_emu10k1 *emu = entry->private_data;

@@ -415,10 +415,8 @@ static ssize_t snd_emu10k1_fx8010_read(struct snd_info_entry *entry,
 		}
 		tmp[idx] = val;
 	}
-	if (copy_to_user(buf, ((char *)tmp) + (pos & 3), count))
-		res = -EFAULT;
-	else
-		res = count;
+	memcpy(buf, ((char *)tmp) + (pos & 3), count);
+	res = count;
 	kfree(tmp);
 	return res;
 }

@@ -1110,14 +1110,13 @@ static int snd_mixart_free(struct mixart_mgr *mgr)
  */
 static ssize_t snd_mixart_BA0_read(struct snd_info_entry *entry,
 				   void *file_private_data,
-				   struct file *file, char __user *buf,
+				   struct file *file, char *buf,
 				   size_t count, loff_t pos)
 {
 	struct mixart_mgr *mgr = entry->private_data;
 
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
-	if (copy_to_user_fromio(buf, MIXART_MEM(mgr, pos), count))
-		return -EFAULT;
+	memcpy_fromio(buf, MIXART_MEM(mgr, pos), count);
 	return count;
 }
 

@@ -1126,14 +1125,13 @@ static ssize_t snd_mixart_BA0_read(struct snd_info_entry *entry,
  */
 static ssize_t snd_mixart_BA1_read(struct snd_info_entry *entry,
 				   void *file_private_data,
-				   struct file *file, char __user *buf,
+				   struct file *file, char *buf,
 				   size_t count, loff_t pos)
 {
 	struct mixart_mgr *mgr = entry->private_data;
 
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
-	if (copy_to_user_fromio(buf, MIXART_REG(mgr, pos), count))
-		return -EFAULT;
+	memcpy_fromio(buf, MIXART_REG(mgr, pos), count);
 	return count;
 }
 

@@ -9763,7 +9763,7 @@ static ssize_t scarlett2_devmap_read(
 	struct snd_info_entry *entry,
 	void                  *file_private_data,
 	struct file           *file,
-	char __user           *buf,
+	char                  *buf,
 	size_t                 count,
 	loff_t                 pos)
 {

@@ -9785,7 +9785,7 @@ static ssize_t scarlett2_devmap_read(
 	while (count > 0) {
 		/* SCARLETT2_USB_GET_DEVMAP reads only on block boundaries,
 		 * so we need to read a whole block and copy the requested
-		 * chunk to userspace.
+		 * chunk out of it.
 		 */
 
 		__le32 req;

@@ -9800,7 +9800,7 @@ static ssize_t scarlett2_devmap_read(
 					 block_size,
 					 entry->size - block_start);
 
-		/* size of the chunk to copy to userspace */
+		/* size of the chunk to copy out of the block */
 		size_t copy_size = min_t(size_t, count, read_size - offset);
 
 		/* request the block */

@@ -9810,8 +9810,7 @@ static ssize_t scarlett2_devmap_read(
 		if (err < 0)
 			return copied ? copied : err;
 
-		if (copy_to_user(buf, resp_buf + offset, copy_size))
-			return -EFAULT;
+		memcpy(buf, resp_buf + offset, copy_size);
 
 		buf += copy_size;
 		pos += copy_size;