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Commit 718a9163 authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Linus Torvalds
Browse files

devpts: factor out PTY index allocation 



Factor out the code used to allocate/free a pts index into new interfaces,
devpts_new_index() and devpts_kill_index().  This localizes the external data
structures used in managing the pts indices.

[akpm@linux-foundation.org: undo accidental mutex2sem conversion]
Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: default avatarSerge Hallyn <serue@us.ibm.com>
Signed-off-by: default avatarMatt Helsley <matthltc@us.ibm.com>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f8f9d66

drivers/char/tty_io.c

+6 −34
Original line number Diff line number Diff line
@@ -91,7 +91,6 @@ 
#include <linux/module.h>

#include <linux/smp_lock.h>

#include <linux/device.h>

#include <linux/idr.h>

#include <linux/wait.h>

#include <linux/bitops.h>

#include <linux/delay.h>
@@ -137,9 +136,6 @@ EXPORT_SYMBOL(tty_mutex); 


#ifdef CONFIG_UNIX98_PTYS

extern struct tty_driver *ptm_driver;	/* Unix98 pty masters; for /dev/ptmx */

extern int pty_limit;			/* Config limit on Unix98 ptys */

static DEFINE_IDR(allocated_ptys);

static DEFINE_MUTEX(allocated_ptys_lock);

static int ptmx_open(struct inode *, struct file *);

#endif
@@ -2639,15 +2635,9 @@ static void release_dev(struct file *filp) 
	 */

	release_tty(tty, idx);



#ifdef CONFIG_UNIX98_PTYS

	/* Make this pty number available for reallocation */

	if (devpts) {

		mutex_lock(&allocated_ptys_lock);

		idr_remove(&allocated_ptys, idx);

		mutex_unlock(&allocated_ptys_lock);

	}

#endif



	if (devpts)

		devpts_kill_index(idx);

}



/**
@@ -2803,29 +2793,13 @@ static int ptmx_open(struct inode *inode, struct file *filp) 
	struct tty_struct *tty;

	int retval;

	int index;

	int idr_ret;



	nonseekable_open(inode, filp);



	/* find a device that is not in use. */

	mutex_lock(&allocated_ptys_lock);

	if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {

		mutex_unlock(&allocated_ptys_lock);

		return -ENOMEM;

	}

	idr_ret = idr_get_new(&allocated_ptys, NULL, &index);

	if (idr_ret < 0) {

		mutex_unlock(&allocated_ptys_lock);

		if (idr_ret == -EAGAIN)

			return -ENOMEM;

		return -EIO;

	}

	if (index >= pty_limit) {

		idr_remove(&allocated_ptys, index);

		mutex_unlock(&allocated_ptys_lock);

		return -EIO;

	}

	mutex_unlock(&allocated_ptys_lock);

	index = devpts_new_index();

	if (index < 0)

		return index;



	mutex_lock(&tty_mutex);

	retval = init_dev(ptm_driver, index, &tty);
@@ -2850,9 +2824,7 @@ static int ptmx_open(struct inode *inode, struct file *filp) 
	release_dev(filp);

	return retval;

out:

	mutex_lock(&allocated_ptys_lock);

	idr_remove(&allocated_ptys, index);

	mutex_unlock(&allocated_ptys_lock);

	devpts_kill_index(index);

	return retval;

}

#endif

fs/devpts/inode.c

+42 −1
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#include <linux/namei.h>

#include <linux/mount.h>

#include <linux/tty.h>

#include <linux/mutex.h>

#include <linux/idr.h>

#include <linux/devpts_fs.h>

#include <linux/parser.h>

#include <linux/fsnotify.h>
@@ -26,6 +28,10 @@ 


#define DEVPTS_DEFAULT_MODE 0600



extern int pty_limit;			/* Config limit on Unix98 ptys */

static DEFINE_IDR(allocated_ptys);

static DEFINE_MUTEX(allocated_ptys_lock);



static struct vfsmount *devpts_mnt;

static struct dentry *devpts_root;
@@ -171,9 +177,44 @@ static struct dentry *get_node(int num) 
	return lookup_one_len(s, root, sprintf(s, "%d", num));

}



int devpts_new_index(void)

{

	int index;

	int idr_ret;



retry:

	if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {

		return -ENOMEM;

	}



	mutex_lock(&allocated_ptys_lock);

	idr_ret = idr_get_new(&allocated_ptys, NULL, &index);

	if (idr_ret < 0) {

		mutex_unlock(&allocated_ptys_lock);

		if (idr_ret == -EAGAIN)

			goto retry;

		return -EIO;

	}



	if (index >= pty_limit) {

		idr_remove(&allocated_ptys, index);

		mutex_unlock(&allocated_ptys_lock);

		return -EIO;

	}

	mutex_unlock(&allocated_ptys_lock);

	return index;

}



void devpts_kill_index(int idx)

{

	mutex_lock(&allocated_ptys_lock);

	idr_remove(&allocated_ptys, idx);

	mutex_unlock(&allocated_ptys_lock);

}



int devpts_pty_new(struct tty_struct *tty)

{

	int number = tty->index;

	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */

	struct tty_driver *driver = tty->driver;

	dev_t device = MKDEV(driver->major, driver->minor_start+number);

	struct dentry *dentry;

include/linux/devpts_fs.h

+4 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 


#ifdef CONFIG_UNIX98_PTYS



int devpts_new_index(void);

void devpts_kill_index(int idx);

int devpts_pty_new(struct tty_struct *tty);      /* mknod in devpts */

struct tty_struct *devpts_get_tty(int number);	 /* get tty structure */

void devpts_pty_kill(int number);		 /* unlink */
@@ -24,6 +26,8 @@ void devpts_pty_kill(int number); /* unlink */ 
#else



/* Dummy stubs in the no-pty case */

static inline int devpts_new_index(void) { return -EINVAL; }

static inline void devpts_kill_index(int idx) { }

static inline int devpts_pty_new(struct tty_struct *tty) { return -EINVAL; }

static inline struct tty_struct *devpts_get_tty(int number) { return NULL; }

static inline void devpts_pty_kill(int number) { }