From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> Subject: [RFC][PATCH 1/4]: 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. Changelog: - Version 0: Based on earlier versions from Serge Hallyn and Matt Helsley. Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> --- drivers/char/tty_io.c | 40 ++++++---------------------------------- fs/devpts/inode.c | 42 +++++++++++++++++++++++++++++++++++++++++- include/linux/devpts_fs.h | 4 ++++ 3 files changed, 51 insertions(+), 35 deletions(-) Index: linux-2.6.24/drivers/char/tty_io.c =================================================================== --- linux-2.6.24.orig/drivers/char/tty_io.c 2008-01-24 14:58:37.000000000 -0800 +++ linux-2.6.24/drivers/char/tty_io.c 2008-02-05 17:17:11.000000000 -0800 @@ -90,7 +90,6 @@ #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> @@ -136,9 +135,6 @@ 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 DECLARE_MUTEX(allocated_ptys_lock); static int ptmx_open(struct inode *, struct file *); #endif @@ -2568,15 +2564,9 @@ static void release_dev(struct file * fi */ release_tty(tty, idx); -#ifdef CONFIG_UNIX98_PTYS /* Make this pty number available for reallocation */ - if (devpts) { - down(&allocated_ptys_lock); - idr_remove(&allocated_ptys, idx); - up(&allocated_ptys_lock); - } -#endif - + if (devpts) + devpts_kill_index(idx); } /** @@ -2732,29 +2722,13 @@ static int ptmx_open(struct inode * inod struct tty_struct *tty; int retval; int index; - int idr_ret; nonseekable_open(inode, filp); /* find a device that is not in use. */ - down(&allocated_ptys_lock); - if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { - up(&allocated_ptys_lock); - return -ENOMEM; - } - idr_ret = idr_get_new(&allocated_ptys, NULL, &index); - if (idr_ret < 0) { - up(&allocated_ptys_lock); - if (idr_ret == -EAGAIN) - return -ENOMEM; - return -EIO; - } - if (index >= pty_limit) { - idr_remove(&allocated_ptys, index); - up(&allocated_ptys_lock); - return -EIO; - } - up(&allocated_ptys_lock); + index = devpts_new_index(); + if (index < 0) + return index; mutex_lock(&tty_mutex); retval = init_dev(ptm_driver, index, &tty); @@ -2781,9 +2755,7 @@ out1: release_dev(filp); return retval; out: - down(&allocated_ptys_lock); - idr_remove(&allocated_ptys, index); - up(&allocated_ptys_lock); + devpts_kill_index(index); return retval; } #endif Index: linux-2.6.24/fs/devpts/inode.c =================================================================== --- linux-2.6.24.orig/fs/devpts/inode.c 2008-01-24 14:58:37.000000000 -0800 +++ linux-2.6.24/fs/devpts/inode.c 2008-02-05 17:17:11.000000000 -0800 @@ -17,12 +17,17 @@ #include <linux/namei.h> #include <linux/mount.h> #include <linux/tty.h> +#include <linux/idr.h> #include <linux/devpts_fs.h> #include <linux/parser.h> #include <linux/fsnotify.h> #define DEVPTS_SUPER_MAGIC 0x1cd1 +extern int pty_limit; /* Config limit on Unix98 ptys */ +static DEFINE_IDR(allocated_ptys); +static DECLARE_MUTEX(allocated_ptys_lock); + static struct vfsmount *devpts_mnt; static struct dentry *devpts_root; @@ -156,9 +161,44 @@ 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; + } + + down(&allocated_ptys_lock); + idr_ret = idr_get_new(&allocated_ptys, NULL, &index); + if (idr_ret < 0) { + up(&allocated_ptys_lock); + if (idr_ret == -EAGAIN) + goto retry; + return -EIO; + } + + if (index >= pty_limit) { + idr_remove(&allocated_ptys, index); + up(&allocated_ptys_lock); + return -EIO; + } + up(&allocated_ptys_lock); + return index; +} + +void devpts_kill_index(int idx) +{ + down(&allocated_ptys_lock); + idr_remove(&allocated_ptys, idx); + up(&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; Index: linux-2.6.24/include/linux/devpts_fs.h =================================================================== --- linux-2.6.24.orig/include/linux/devpts_fs.h 2008-01-24 14:58:37.000000000 -0800 +++ linux-2.6.24/include/linux/devpts_fs.h 2008-02-05 17:17:11.000000000 -0800 @@ -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); /* u #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) { } _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers