Messages in this thread | | | Date | Thu, 17 Apr 2008 10:42:41 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH]: Factor out PTY index allocation |
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Quoting sukadev@us.ibm.com (sukadev@us.ibm.com): > We noticed this while working on pts namespaces and believe this might > be an useful change even as we rework our pts/device namespace approach. > > --- > > From: Sukadev Bhattiprolu <sukadev@us.ibm.com> > Subject: [PATCH]: 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. > > 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>
No traces of devpts namespaces here, so I assume this should be non-offensive and fine for inclusion.
thanks, -serge
> --- > 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: 2.6.25-rc8-mm2/include/linux/devpts_fs.h > =================================================================== > --- 2.6.25-rc8-mm2.orig/include/linux/devpts_fs.h 2008-01-26 09:49:16.000000000 -0800 > +++ 2.6.25-rc8-mm2/include/linux/devpts_fs.h 2008-04-16 09:51:15.000000000 -0700 > @@ -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) { } > Index: 2.6.25-rc8-mm2/drivers/char/tty_io.c > =================================================================== > --- 2.6.25-rc8-mm2.orig/drivers/char/tty_io.c 2008-04-16 09:51:11.000000000 -0700 > +++ 2.6.25-rc8-mm2/drivers/char/tty_io.c 2008-04-16 09:51:15.000000000 -0700 > @@ -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 > > @@ -2636,15 +2632,9 @@ static void release_dev(struct file *fil > */ > 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); > } > > /** > @@ -2800,29 +2790,13 @@ static int ptmx_open(struct inode *inode > 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); > @@ -2847,9 +2821,7 @@ 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 > Index: 2.6.25-rc8-mm2/fs/devpts/inode.c > =================================================================== > --- 2.6.25-rc8-mm2.orig/fs/devpts/inode.c 2008-02-27 15:17:59.000000000 -0800 > +++ 2.6.25-rc8-mm2/fs/devpts/inode.c 2008-04-16 09:51:15.000000000 -0700 > @@ -17,6 +17,7 @@ > #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> > @@ -26,6 +27,10 @@ > > #define DEVPTS_DEFAULT_MODE 0600 > > +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; > > @@ -171,9 +176,44 @@ 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;
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