Messages in this thread Patches in this message | | | Subject | [PATCH] revert behaviour of pty allocation in 2.6 | From | Andrew Clayton <> | Date | Mon, 17 May 2004 17:14:51 +0100 |
| |
Hello,
Here is a patch which is mainly
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.5/2.6.5-mm5/broken-out/pty-allocation-first-fit.patch
with a couple of changes.
That patch didn't quite work....
It changes back to the old behaviour of re-allocating used pty's rather then just allocating them sequentially.
This is my first kernel patch, but it seems to work and do the right thing ;)
It is against 2.6.6-bk3
(I've also attached it, if this gets mangled inline)
Please CC me in any replies.
Cheers,
Andrew Clayton
tty_io.c | 51 +++++++++++++++++++++++++++++++++++++++++---------- 1 files changed, 41 insertions(+), 10 deletions(-)
diff -up a/drivers/char/tty_io.c b/drivers/char/tty_io.c --- a/drivers/char/tty_io.c 2004-05-17 15:24:07.829691814 +0100 +++ b/drivers/char/tty_io.c 2004-05-17 15:25:25.659976275 +0100 @@ -91,6 +91,7 @@ #include <linux/module.h> #include <linux/smp_lock.h> #include <linux/device.h> +#include <linux/idr.h> #include <asm/uaccess.h> #include <asm/system.h> @@ -128,6 +129,8 @@ DECLARE_MUTEX(tty_sem); #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 DECLARE_MUTEX(allocated_ptys_lock); #endif extern void disable_early_printk(void); @@ -1295,6 +1298,14 @@ static void release_dev(struct file * fi o_tty->ldisc = ldiscs[N_TTY]; } +#ifdef CONFIG_UNIX98_PTYS + if (filp->f_dentry->d_inode->i_rdev == MKDEV(TTYAUX_MAJOR,2)) { + down(&allocated_ptys_lock); + idr_remove(&allocated_ptys, idx); + up(&allocated_ptys_lock); + } +#endif + /* * The release_mem function takes care of the details of clearing * the slots and preserving the termios structure. @@ -1319,7 +1330,7 @@ static int tty_open(struct inode * inode struct tty_struct *tty; int noctty, retval; struct tty_driver *driver; - int index; + int res, index = -1; dev_t device = inode->i_rdev; unsigned short saved_flags = filp->f_flags; retry_open: @@ -1362,22 +1373,33 @@ retry_open: #ifdef CONFIG_UNIX98_PTYS if (device == MKDEV(TTYAUX_MAJOR,2)) { /* find a device that is not in use. */ - static int next_ptmx_dev = 0; - retval = -1; + down(&allocated_ptys_lock); + if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { + up(&allocated_ptys_lock); + return -ENOMEM; + } + res = idr_get_new(&allocated_ptys, NULL); + index = res & MAX_ID_MASK; + if (index >= pty_limit) { + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + return -EIO; + } driver = ptm_driver; - while (driver->refcount < pty_limit) { - index = next_ptmx_dev; - next_ptmx_dev = (next_ptmx_dev+1) % driver->num; - if (!init_dev(driver, index, &tty)) - goto ptmx_found; /* ok! */ + retval = init_dev(driver, index, &tty); + if (retval) { + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + return retval; } - return -EIO; /* no free ptys */ - ptmx_found: set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ if (devpts_pty_new(tty->link)) { /* BADNESS - need to destroy both ptm and pts! */ + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); return -ENOMEM; } + up(&allocated_ptys_lock); noctty = 1; } else #endif @@ -1415,6 +1437,14 @@ got_driver: tty->name); #endif +#ifdef CONFIG_UNIX98_PTYS + if (index != -1) { + down(&allocated_ptys_lock); + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + } +#endif + release_dev(filp); if (retval != -ERESTARTSYS) return retval; @@ -2400,6 +2430,7 @@ static struct cdev vc0_cdev; */ static int __init tty_init(void) { + idr_init(&allocated_ptys); cdev_init(&tty_cdev, &tty_fops); if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0) --- a/drivers/char/tty_io.c 2004-05-17 15:24:07.829691814 +0100 +++ b/drivers/char/tty_io.c 2004-05-17 15:25:25.659976275 +0100 @@ -91,6 +91,7 @@ #include <linux/module.h> #include <linux/smp_lock.h> #include <linux/device.h> +#include <linux/idr.h> #include <asm/uaccess.h> #include <asm/system.h> @@ -128,6 +129,8 @@ DECLARE_MUTEX(tty_sem); #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 DECLARE_MUTEX(allocated_ptys_lock); #endif extern void disable_early_printk(void); @@ -1295,6 +1298,14 @@ static void release_dev(struct file * fi o_tty->ldisc = ldiscs[N_TTY]; } +#ifdef CONFIG_UNIX98_PTYS + if (filp->f_dentry->d_inode->i_rdev == MKDEV(TTYAUX_MAJOR,2)) { + down(&allocated_ptys_lock); + idr_remove(&allocated_ptys, idx); + up(&allocated_ptys_lock); + } +#endif + /* * The release_mem function takes care of the details of clearing * the slots and preserving the termios structure. @@ -1319,7 +1330,7 @@ static int tty_open(struct inode * inode struct tty_struct *tty; int noctty, retval; struct tty_driver *driver; - int index; + int res, index = -1; dev_t device = inode->i_rdev; unsigned short saved_flags = filp->f_flags; retry_open: @@ -1362,22 +1373,33 @@ retry_open: #ifdef CONFIG_UNIX98_PTYS if (device == MKDEV(TTYAUX_MAJOR,2)) { /* find a device that is not in use. */ - static int next_ptmx_dev = 0; - retval = -1; + down(&allocated_ptys_lock); + if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { + up(&allocated_ptys_lock); + return -ENOMEM; + } + res = idr_get_new(&allocated_ptys, NULL); + index = res & MAX_ID_MASK; + if (index >= pty_limit) { + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + return -EIO; + } driver = ptm_driver; - while (driver->refcount < pty_limit) { - index = next_ptmx_dev; - next_ptmx_dev = (next_ptmx_dev+1) % driver->num; - if (!init_dev(driver, index, &tty)) - goto ptmx_found; /* ok! */ + retval = init_dev(driver, index, &tty); + if (retval) { + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + return retval; } - return -EIO; /* no free ptys */ - ptmx_found: set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ if (devpts_pty_new(tty->link)) { /* BADNESS - need to destroy both ptm and pts! */ + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); return -ENOMEM; } + up(&allocated_ptys_lock); noctty = 1; } else #endif @@ -1415,6 +1437,14 @@ got_driver: tty->name); #endif +#ifdef CONFIG_UNIX98_PTYS + if (index != -1) { + down(&allocated_ptys_lock); + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + } +#endif + release_dev(filp); if (retval != -ERESTARTSYS) return retval; @@ -2400,6 +2430,7 @@ static struct cdev vc0_cdev; */ static int __init tty_init(void) { + idr_init(&allocated_ptys); cdev_init(&tty_cdev, &tty_fops); if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0) | |