Merge branch 'topic/soundcore-preclaim' into for-linus
* topic/soundcore-preclaim: sound: make OSS device number claiming optional and schedule its removal sound: request char-major-* module aliases for missing OSS devices chrdev: implement __[un]register_chrdev()
This commit is contained in:
commit
3827119e20
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@ -468,3 +468,27 @@ Why: cpu_policy_rwsem has a new cleaner definition making it local to
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cpufreq core and contained inside cpufreq.c. Other dependent
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drivers should not use it in order to safely avoid lockdep issues.
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Who: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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----------------------------
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What: sound-slot/service-* module aliases and related clutters in
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sound/sound_core.c
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When: August 2010
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Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
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(14) and requests modules using custom sound-slot/service-*
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module aliases. The only benefit of doing this is allowing
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use of custom module aliases which might as well be considered
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a bug at this point. This preemptive claiming prevents
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alternative OSS implementations.
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Till the feature is removed, the kernel will be requesting
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both sound-slot/service-* and the standard char-major-* module
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aliases and allow turning off the pre-claiming selectively via
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CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
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kernel parameter.
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After the transition phase is complete, both the custom module
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aliases and switches to disable it will go away. This removal
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will also allow making ALSA OSS emulation independent of
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sound_core. The dependency will be broken then too.
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Who: Tejun Heo <tj@kernel.org>
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@ -237,8 +237,10 @@ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
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}
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/**
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* register_chrdev() - Register a major number for character devices.
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* __register_chrdev() - create and register a cdev occupying a range of minors
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* @major: major device number or 0 for dynamic allocation
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* @baseminor: first of the requested range of minor numbers
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* @count: the number of minor numbers required
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* @name: name of this range of devices
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* @fops: file operations associated with this devices
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*
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@ -254,19 +256,17 @@ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
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* /dev. It only helps to keep track of the different owners of devices. If
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* your module name has only one type of devices it's ok to use e.g. the name
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* of the module here.
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*
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* This function registers a range of 256 minor numbers. The first minor number
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* is 0.
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*/
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int register_chrdev(unsigned int major, const char *name,
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const struct file_operations *fops)
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int __register_chrdev(unsigned int major, unsigned int baseminor,
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unsigned int count, const char *name,
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const struct file_operations *fops)
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{
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struct char_device_struct *cd;
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struct cdev *cdev;
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char *s;
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int err = -ENOMEM;
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cd = __register_chrdev_region(major, 0, 256, name);
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cd = __register_chrdev_region(major, baseminor, count, name);
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if (IS_ERR(cd))
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return PTR_ERR(cd);
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@ -280,7 +280,7 @@ int register_chrdev(unsigned int major, const char *name,
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for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
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*s = '!';
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err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
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err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
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if (err)
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goto out;
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@ -290,7 +290,7 @@ int register_chrdev(unsigned int major, const char *name,
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out:
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kobject_put(&cdev->kobj);
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out2:
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kfree(__unregister_chrdev_region(cd->major, 0, 256));
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kfree(__unregister_chrdev_region(cd->major, baseminor, count));
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return err;
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}
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@ -316,10 +316,23 @@ void unregister_chrdev_region(dev_t from, unsigned count)
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}
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}
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void unregister_chrdev(unsigned int major, const char *name)
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/**
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* __unregister_chrdev - unregister and destroy a cdev
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* @major: major device number
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* @baseminor: first of the range of minor numbers
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* @count: the number of minor numbers this cdev is occupying
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* @name: name of this range of devices
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*
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* Unregister and destroy the cdev occupying the region described by
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* @major, @baseminor and @count. This function undoes what
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* __register_chrdev() did.
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*/
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void __unregister_chrdev(unsigned int major, unsigned int baseminor,
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unsigned int count, const char *name)
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{
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struct char_device_struct *cd;
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cd = __unregister_chrdev_region(major, 0, 256);
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cd = __unregister_chrdev_region(major, baseminor, count);
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if (cd && cd->cdev)
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cdev_del(cd->cdev);
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kfree(cd);
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@ -568,6 +581,6 @@ EXPORT_SYMBOL(cdev_alloc);
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EXPORT_SYMBOL(cdev_del);
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EXPORT_SYMBOL(cdev_add);
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EXPORT_SYMBOL(cdev_index);
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EXPORT_SYMBOL(register_chrdev);
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EXPORT_SYMBOL(unregister_chrdev);
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EXPORT_SYMBOL(__register_chrdev);
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EXPORT_SYMBOL(__unregister_chrdev);
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EXPORT_SYMBOL(directly_mappable_cdev_bdi);
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@ -1998,12 +1998,25 @@ extern void bd_release_from_disk(struct block_device *, struct gendisk *);
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#define CHRDEV_MAJOR_HASH_SIZE 255
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extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
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extern int register_chrdev_region(dev_t, unsigned, const char *);
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extern int register_chrdev(unsigned int, const char *,
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const struct file_operations *);
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extern void unregister_chrdev(unsigned int, const char *);
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extern int __register_chrdev(unsigned int major, unsigned int baseminor,
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unsigned int count, const char *name,
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const struct file_operations *fops);
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extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
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unsigned int count, const char *name);
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extern void unregister_chrdev_region(dev_t, unsigned);
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extern void chrdev_show(struct seq_file *,off_t);
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static inline int register_chrdev(unsigned int major, const char *name,
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const struct file_operations *fops)
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{
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return __register_chrdev(major, 0, 256, name, fops);
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}
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static inline void unregister_chrdev(unsigned int major, const char *name)
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{
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__unregister_chrdev(major, 0, 256, name);
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}
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/* fs/block_dev.c */
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#define BDEVNAME_SIZE 32 /* Largest string for a blockdev identifier */
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#define BDEVT_SIZE 10 /* Largest string for MAJ:MIN for blkdev */
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@ -32,6 +32,34 @@ config SOUND_OSS_CORE
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bool
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default n
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config SOUND_OSS_CORE_PRECLAIM
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bool "Preclaim OSS device numbers"
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depends on SOUND_OSS_CORE
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default y
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help
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With this option enabled, the kernel will claim all OSS device
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numbers if any OSS support (native or emulation) is enabled
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whether the respective module is loaded or not and try to load the
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appropriate module using sound-slot/service-* and char-major-*
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module aliases when one of the device numbers is opened. With
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this option disabled, kernel will only claim actually in-use
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device numbers and opening a missing device will generate only the
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standard char-major-* aliases.
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The only visible difference is use of additional module aliases
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and whether OSS sound devices appear multiple times in
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/proc/devices. sound-slot/service-* module aliases are scheduled
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to be removed (ie. PRECLAIM won't be available) and this option is
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to make the transition easier. This option can be overridden
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during boot using the kernel parameter soundcore.preclaim_oss.
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Disabling this allows alternative OSS implementations.
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Please read Documentation/feature-removal-schedule.txt for
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details.
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If unusre, say Y.
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source "sound/oss/dmasound/Kconfig"
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if !M68K
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@ -127,6 +127,46 @@ extern int msnd_classic_init(void);
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extern int msnd_pinnacle_init(void);
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#endif
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/*
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* By default, OSS sound_core claims full legacy minor range (0-255)
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* of SOUND_MAJOR to trap open attempts to any sound minor and
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* requests modules using custom sound-slot/service-* module aliases.
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* The only benefit of doing this is allowing use of custom module
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* aliases instead of the standard char-major-* ones. This behavior
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* prevents alternative OSS implementation and is scheduled to be
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* removed.
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*
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* CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
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* parameter are added to allow distros and developers to try and
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* switch to alternative implementations without needing to rebuild
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* the kernel in the meantime. If preclaim_oss is non-zero, the
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* kernel will behave the same as before. All SOUND_MAJOR minors are
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* preclaimed and the custom module aliases along with standard chrdev
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* ones are emitted if a missing device is opened. If preclaim_oss is
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* zero, sound_core only grabs what's actually in use and for missing
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* devices only the standard chrdev aliases are requested.
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*
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* All these clutters are scheduled to be removed along with
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* sound-slot/service-* module aliases. Please take a look at
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* feature-removal-schedule.txt for details.
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*/
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#ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
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static int preclaim_oss = 1;
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#else
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static int preclaim_oss = 0;
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#endif
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module_param(preclaim_oss, int, 0444);
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static int soundcore_open(struct inode *, struct file *);
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static const struct file_operations soundcore_fops =
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{
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/* We must have an owner or the module locking fails */
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.owner = THIS_MODULE,
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.open = soundcore_open,
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};
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/*
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* Low level list operator. Scan the ordered list, find a hole and
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* join into it. Called with the lock asserted
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@ -219,8 +259,9 @@ static int sound_insert_unit(struct sound_unit **list, const struct file_operati
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if (!s)
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return -ENOMEM;
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spin_lock(&sound_loader_lock);
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retry:
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r = __sound_insert_unit(s, list, fops, index, low, top);
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spin_unlock(&sound_loader_lock);
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else
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sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
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if (!preclaim_oss) {
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/*
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* Something else might have grabbed the minor. If
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* first free slot is requested, rescan with @low set
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* to the next unit; otherwise, -EBUSY.
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*/
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r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
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&soundcore_fops);
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if (r < 0) {
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spin_lock(&sound_loader_lock);
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__sound_remove_unit(list, s->unit_minor);
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if (index < 0) {
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low = s->unit_minor + SOUND_STEP;
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goto retry;
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}
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spin_unlock(&sound_loader_lock);
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return -EBUSY;
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}
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}
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device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
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NULL, s->name+6);
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return r;
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return s->unit_minor;
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fail:
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fail:
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kfree(s);
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return r;
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}
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p = __sound_remove_unit(list, unit);
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spin_unlock(&sound_loader_lock);
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if (p) {
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if (!preclaim_oss)
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__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
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p->name);
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device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
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kfree(p);
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}
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@ -491,19 +555,6 @@ void unregister_sound_dsp(int unit)
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EXPORT_SYMBOL(unregister_sound_dsp);
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/*
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* Now our file operations
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*/
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static int soundcore_open(struct inode *, struct file *);
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static const struct file_operations soundcore_fops=
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{
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/* We must have an owner or the module locking fails */
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.owner = THIS_MODULE,
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.open = soundcore_open,
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};
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static struct sound_unit *__look_for_unit(int chain, int unit)
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{
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struct sound_unit *s;
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s = __look_for_unit(chain, unit);
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if (s)
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new_fops = fops_get(s->unit_fops);
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if (!new_fops) {
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if (preclaim_oss && !new_fops) {
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spin_unlock(&sound_loader_lock);
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/*
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* Please, don't change this order or code.
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* For ALSA slot means soundcard and OSS emulation code
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@ -550,6 +602,17 @@ static int soundcore_open(struct inode *inode, struct file *file)
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*/
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request_module("sound-slot-%i", unit>>4);
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request_module("sound-service-%i-%i", unit>>4, chain);
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/*
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* sound-slot/service-* module aliases are scheduled
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* for removal in favor of the standard char-major-*
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* module aliases. For the time being, generate both
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* the legacy and standard module aliases to ease
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* transition.
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*/
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if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
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request_module("char-major-%d", SOUND_MAJOR);
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spin_lock(&sound_loader_lock);
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s = __look_for_unit(chain, unit);
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if (s)
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@ -593,7 +656,8 @@ static void cleanup_oss_soundcore(void)
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static int __init init_oss_soundcore(void)
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{
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if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
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if (preclaim_oss &&
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register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
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printk(KERN_ERR "soundcore: sound device already in use.\n");
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return -EBUSY;
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}
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