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devpts: factor out PTY index allocation

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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: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sukadev Bhattiprolu 2008-04-30 00:54:21 -07:00 committed by Linus Torvalds
parent 4f8f9d66cd
commit 718a916338
3 changed files with 52 additions and 35 deletions
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40
drivers/char/tty_io.c
View file

@ -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 @@ out1:
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

43
fs/devpts/inode.c
View file

@ -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;

4
include/linux/devpts_fs.h
View file

@ -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) { }