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authorSukadev Bhattiprolu <sukadev@us.ibm.com>2008-04-30 03:54:21 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 11:29:48 -0400
commit718a916338e821a10961e6a7a17430c18e5e58d9 (patch)
treeb261fd36e7a4f642223668596c85da62b60729a4 /fs/devpts/inode.c
parent4f8f9d66cdac4845409f7520e4f287a1907a6bf9 (diff)
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: 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>
Diffstat (limited to 'fs/devpts/inode.c')
-rw-r--r--fs/devpts/inode.c43
1 files changed, 42 insertions, 1 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index f120e1207874..285b64a8b06e 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -17,6 +17,8 @@
17#include <linux/namei.h> 17#include <linux/namei.h>
18#include <linux/mount.h> 18#include <linux/mount.h>
19#include <linux/tty.h> 19#include <linux/tty.h>
20#include <linux/mutex.h>
21#include <linux/idr.h>
20#include <linux/devpts_fs.h> 22#include <linux/devpts_fs.h>
21#include <linux/parser.h> 23#include <linux/parser.h>
22#include <linux/fsnotify.h> 24#include <linux/fsnotify.h>
@@ -26,6 +28,10 @@
26 28
27#define DEVPTS_DEFAULT_MODE 0600 29#define DEVPTS_DEFAULT_MODE 0600
28 30
31extern int pty_limit; /* Config limit on Unix98 ptys */
32static DEFINE_IDR(allocated_ptys);
33static DEFINE_MUTEX(allocated_ptys_lock);
34
29static struct vfsmount *devpts_mnt; 35static struct vfsmount *devpts_mnt;
30static struct dentry *devpts_root; 36static struct dentry *devpts_root;
31 37
@@ -171,9 +177,44 @@ static struct dentry *get_node(int num)
171 return lookup_one_len(s, root, sprintf(s, "%d", num)); 177 return lookup_one_len(s, root, sprintf(s, "%d", num));
172} 178}
173 179
180int devpts_new_index(void)
181{
182 int index;
183 int idr_ret;
184
185retry:
186 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
187 return -ENOMEM;
188 }
189
190 mutex_lock(&allocated_ptys_lock);
191 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
192 if (idr_ret < 0) {
193 mutex_unlock(&allocated_ptys_lock);
194 if (idr_ret == -EAGAIN)
195 goto retry;
196 return -EIO;
197 }
198
199 if (index >= pty_limit) {
200 idr_remove(&allocated_ptys, index);
201 mutex_unlock(&allocated_ptys_lock);
202 return -EIO;
203 }
204 mutex_unlock(&allocated_ptys_lock);
205 return index;
206}
207
208void devpts_kill_index(int idx)
209{
210 mutex_lock(&allocated_ptys_lock);
211 idr_remove(&allocated_ptys, idx);
212 mutex_unlock(&allocated_ptys_lock);
213}
214
174int devpts_pty_new(struct tty_struct *tty) 215int devpts_pty_new(struct tty_struct *tty)
175{ 216{
176 int number = tty->index; 217 int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
177 struct tty_driver *driver = tty->driver; 218 struct tty_driver *driver = tty->driver;
178 dev_t device = MKDEV(driver->major, driver->minor_start+number); 219 dev_t device = MKDEV(driver->major, driver->minor_start+number);
179 struct dentry *dentry; 220 struct dentry *dentry;