remove DEVFS_FL_AUTO_DEVNUM

PATCH In review Christoph Hellwig 4 participants 5 messages Mar 1, 2003 – Mar 2, 2003

Subsystems (2)

Documentation Media (V4L/DVB)

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Christoph Hellwig

author

2003-03-01 17:57 UTC #0 lore raw

PATCH 1/1 remove DEVFS_FL_AUTO_DEVNUM

Remove the DEVFS_FL_AUTO_DEVNUM flag that makes devfs_register() allocate a dev_t for it's caller.

Rationale: while dynamic major/minors are a good idea, devfs is the wrong layer to do it because all code relying on it would break with out devfs.

There were three users (outside the SN1 IRIX compat layer that needs a large rewrite for 2.5/2.6 anyway):

drivers/media/dvb/dvb-core/dvbdev.c:
only used under CONFIG_DVB_DEVFS_ONLY, which isn't exposed in the kernel configurator, removed that code.
drivers/media/radio/miropcm20-rds.c:
driver was devfs-only. Add a miscdevice with dynamic minor allocation.

Documentation/filesystems/devfs/README +0 -7

@@ -1466,13 +1466,6 @@
 keep using the old major and minor numbers. Devfs will take whatever
 values are given for major&minor and pass them onto userspace.
 
-Alternatively, you can have devfs choose unique device numbers for
-you. When you register a character or block device using
-devfs_register you can provide the optional
-DEVFS_FL_AUTO_DEVNUM flag, which will then automatically allocate a
-unique device number (the allocation is separated for the character
-and block devices).
-
 This device number is a 16 bit number, so this leaves plenty of space
 for large numbers of discs and partitions. This scheme can also be
 used for character devices, in particular the tty devices, which are

drivers/media/dvb/dvb-core/dvbdev.c +3 ~~-18~~

@@ -21,8 +21,6 @@
  *
  */
 
-/*#define CONFIG_DVB_DEVFS_ONLY 1*/
-
 #include <linux/config.h>
 #include <linux/version.h>
 #include <linux/module.h>

@@ -56,18 +54,8 @@
 };
 
 
-#ifdef CONFIG_DVB_DEVFS_ONLY
-
-	#define DVB_MAX_IDS              ~0
-	#define nums2minor(num,type,id)  0
-	#define DVB_DEVFS_FLAGS          (DEVFS_FL_DEFAULT|DEVFS_FL_AUTO_DEVNUM)
-
-#else
-
-	#define DVB_MAX_IDS              4
-	#define nums2minor(num,type,id)  ((num << 6) | (id << 4) | type)
-	#define DVB_DEVFS_FLAGS          (DEVFS_FL_DEFAULT)
-
+#define DVB_MAX_IDS              4
+#define nums2minor(num,type,id)  ((num << 6) | (id << 4) | type)
 
 static
 struct dvb_device* dvbdev_find_device (int minor)

@@ -122,9 +110,6 @@
 	.owner =	THIS_MODULE,
 	.open =		dvb_device_open,
 };
-#endif /* CONFIG_DVB_DEVFS_ONLY */
-
-
 
 int dvb_generic_open(struct inode *inode, struct file *file)
 {

@@ -234,7 +219,7 @@
 
 	sprintf(name, "%s%d", dnames[type], id);
 	dvbdev->devfs_handle = devfs_register(adap->devfs_handle, name,
-					      DVB_DEVFS_FLAGS,
+					      DEVFS_FL_DEFAULT,
 					      DVB_MAJOR,
 					      nums2minor(adap->num, type, id),
 					      S_IFCHR | S_IRUSR | S_IWUSR,

===== drivers/media/radio/miropcm20-rds.c 1.6 vs edited =====

drivers/media/radio/miropcm20-rds.c +20 -8

@@ -12,8 +12,9 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
-#include <asm/uaccess.h>
+#include <linux/miscdevice.h>
 #include <linux/devfs_fs_kernel.h>
+#include <asm/uaccess.h>
 #include "miropcm20-rds-core.h"
 
 static char * text_buffer;

@@ -103,28 +104,39 @@
 	}
 }
 
-static struct file_operations rds_f_ops = {
+static struct file_operations rds_fops = {
 	.owner		= THIS_MODULE,
 	.read		= rds_f_read,
 	.open		= rds_f_open,
 	.release	= rds_f_release
 };
 
+static struct miscdevice rds_miscdev = {
+	.minor		= MISC_DYNAMIC_MINOR,
+	.name		= "radiotext"
+	.fops		= &rds_fops,
+};
 
 static int __init miropcm20_rds_init(void)
 {
-	if (!devfs_register(NULL, "v4l/rds/radiotext", 
-				   DEVFS_FL_DEFAULT | DEVFS_FL_AUTO_DEVNUM,
-				   0, 0, S_IRUGO | S_IFCHR, &rds_f_ops, NULL))
-		return -EINVAL;
+	int error;
 
-	printk("miropcm20-rds: userinterface driver loaded.\n");
-	return 0;
+	error = misc_register(&rds_miscdev);
+	if (error)
+		return error;
+
+	error = devfs_mk_symlink(NULL, "v4l/rds/radiotext", 0,
+				 "../misc/radiotext", NULL, NULL);
+	if (error)
+		misc_deregister(&rds_miscdev)
+
+	return error;
 }
 
 static void __exit miropcm20_rds_cleanup(void)
 {
 	devfs_remove("v4l/rds/radiotext");
+	misc_deregister(&rds_miscdev)
 }
 
 module_init(miropcm20_rds_init);

fs/devfs/base.c +0 ~~-14~~

@@ -773,7 +773,6 @@
 {
     struct block_device_operations *ops;
     dev_t dev;
-    unsigned char autogen:1;
     unsigned char removable:1;
 };

@@ -938,8 +937,6 @@
     if ( S_ISLNK (de->mode) ) kfree (de->u.symlink.linkname);
     if ( S_ISCHR (de->mode) && de->u.cdev.autogen )
 	devfs_dealloc_devnum (de->mode, de->u.cdev.dev);
-    if ( S_ISBLK (de->mode) && de->u.bdev.autogen )
-	devfs_dealloc_devnum (de->mode, de->u.bdev.dev);
     WRITE_ENTRY_MAGIC (de, 0);
 #ifdef CONFIG_DEVFS_DEBUG
     spin_lock (&stat_lock);

@@ -1494,17 +1491,6 @@
     {
 	PRINTK ("(%s): creating symlinks is not allowed\n", name);
 	return NULL;
-    }
-    if ( ( S_ISCHR (mode) || S_ISBLK (mode) ) &&
-	 (flags & DEVFS_FL_AUTO_DEVNUM) )
-    {
-	devnum = devfs_alloc_devnum (mode);
-	if (!devnum) {
-	    PRINTK ("(%s): exhausted %s device numbers\n",
-		    name, S_ISCHR (mode) ? "char" : "block");
-	    return NULL;
-	}
-	dev = devnum;
     }
     if ( ( de = _devfs_prepare_leaf (&dir, name, mode) ) == NULL )
     {

include/linux/devfs_fs_kernel.h +0 -2

@@ -13,8 +13,6 @@
 
 #define DEVFS_FL_NONE           0x000 /* This helps to make code more readable
 				       */
-#define DEVFS_FL_AUTO_DEVNUM    0x002 /* Automatically generate device number
-				       */
 #define DEVFS_FL_REMOVABLE      0x008 /* This is a removable media device    */
 #define DEVFS_FL_WAIT           0x010 /* Wait for devfsd to finish           */
 #define DEVFS_FL_CURRENT_OWNER  0x020 /* Set initial ownership to current    */

Christoph Hellwig

2003-03-01 18:05 UTC #1 lore raw

Quoted 1 line · Christoph Hellwig

There were three users (outside the SN1 IRIX compat layer that needs

	      ^^^
	      	  two in fact, the listing of examples below was correct..

H. Peter Anvin

2003-03-02 20:06 UTC #2 lore raw

In reply to Christoph Hellwig

Followup to:  <[email protected]>
By author:    Christoph Hellwig <[email protected]>
In newsgroup: linux.dev.kernel

Quoted 5 lines

Rationale: while dynamic major/minors are a good idea, devfs is the wrong layer to do it because all code relying on it would break with out devfs.

Your first clause here is a *highly* questionable statement...

-hpa

Signature · 3 lines

<[email protected]> at work, <[email protected]> in private!
"Unix gives you enough rope to shoot yourself in the foot."
Architectures needed: cris ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64

Neil Brown

2003-03-02 22:20 UTC #3 lore raw

Quoted 10 lines · On March 2, [email protected] wrote:

Followup to:  <[email protected]>
By author:    Christoph Hellwig <[email protected]>
In newsgroup: linux.dev.kernel
Quoted 5 lines
Rationale: while dynamic major/minors are a good idea, devfs is the wrong layer to do it because all code relying on it would break with out devfs.
Your first clause here is a *highly* questionable statement...

Given the premise "Linus will not allow new static major/minors", I think it is essential :-(

NeilBrown

Quoted 11 lines

-hpa

Signature · 8 lines

<[email protected]> at work, <[email protected]> in private!
"Unix gives you enough rope to shoot yourself in the foot."
Architectures needed: cris ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64
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H. Peter Anvin

2003-03-02 22:31 UTC #4 lore raw

Quoted 4 lines · Neil Brown

Given the premise "Linus will not allow new static major/minors", I think it is essential :-(

It's also a totally nonrealistic premise, which is why new allocations are still happening at the request of Alan and Marcelo.

-hpa