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[PATCH 9/12] tty: Update the tty layer to work with struct pid. [message #17010 is a reply to message #17001]

Wed, 13 December 2006 11:07

ebiederm
Messages: 1354
Registered: February 2006

Senior Member

Of kernel subsystems that work with pids the tty layer
is probably the largest consumer.  But it has the nice
virtue that the assiation with a session only lasts until
the session leader exits.  Which means that no reference
counting is required.  So using struct pid winds up
being a simple optimization to avoid hash table lookups.

In the long term the use of pid_nr also ensures that
when we have multiple pid spaces mixed everything will
work correctly.

Signed-off-by: Eric W. Biederman <eric@maxwell.lnxi.com>
---
 arch/um/drivers/line.c     |    2 +-
 drivers/char/ip2/ip2main.c |    4 +-
 drivers/char/n_tty.c       |   12 ++--
 drivers/char/tty_io.c      |  129 ++++++++++++++++++++++++++-----------------
 drivers/char/vt.c          |    4 +-
 fs/proc/array.c            |    2 +-
 include/linux/init_task.h  |    2 +-
 include/linux/sched.h      |    2 +-
 include/linux/tty.h        |    4 +-
 kernel/fork.c              |    2 +-
 kernel/sys.c               |    1 -
 11 files changed, 95 insertions(+), 69 deletions(-)

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 83301e1..3c1a1d4 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -737,7 +737,7 @@ static irqreturn_t winch_interrupt(int irq, void *data)
 		line = tty->driver_data;
 		chan_window_size(&line->chan_list, &tty->winsize.ws_row,
 				 &tty->winsize.ws_col);
-		kill_pg(tty->pgrp, SIGWINCH, 1);
+		kill_pgrp(tty->pgrp, SIGWINCH, 1);
 	}
  out:
 	if(winch->fd != -1)
diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 7c70310..83c7258 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -1271,8 +1271,8 @@ static void do_input(struct work_struct *work)
 // code duplicated from n_tty (ldisc)
 static inline void  isig(int sig, struct tty_struct *tty, int flush)
 {
-	if (tty->pgrp > 0)
-		kill_pg(tty->pgrp, sig, 1);
+	if (tty->pgrp)
+		kill_pgrp(tty->pgrp, sig, 1);
 	if (flush || !L_NOFLSH(tty)) {
 		if ( tty->ldisc.flush_buffer )  
 			tty->ldisc.flush_buffer(tty);
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 7f1ded8..2b50a50 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -579,8 +579,8 @@ static void eraser(unsigned char c, struct tty_struct *tty)
  
 static inline void isig(int sig, struct tty_struct *tty, int flush)
 {
-	if (tty->pgrp > 0)
-		kill_pg(tty->pgrp, sig, 1);
+	if (tty->pgrp)
+		kill_pgrp(tty->pgrp, sig, 1);
 	if (flush || !L_NOFLSH(tty)) {
 		n_tty_flush_buffer(tty);
 		if (tty->driver->flush_buffer)
@@ -1185,13 +1185,13 @@ static int job_control(struct tty_struct *tty, struct file *file)
 	/* don't stop on /dev/console */
 	if (file->f_op->write != redirected_tty_write &&
 	    current->signal->tty == tty) {
-		if (tty->pgrp <= 0)
-			printk("read_chan: tty->pgrp <= 0!\n");
-		else if (process_group(current) != tty->pgrp) {
+		if (!tty->pgrp)
+			printk("read_chan: no tty->pgrp!\n");
+		else if (task_pgrp(current) != tty->pgrp) {
 			if (is_ignored(SIGTTIN) ||
 			    is_current_pgrp_orphaned())
 				return -EIO;
-			kill_pg(process_group(current), SIGTTIN, 1);
+			kill_pgrp(task_pgrp(current), SIGTTIN, 1);
 			return -ERESTARTSYS;
 		}
 	}
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d8fdf45..fe98f8c 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -155,7 +155,7 @@ int tty_ioctl(struct inode * inode, struct file * file,
 	      unsigned int cmd, unsigned long arg);
 static int tty_fasync(int fd, struct file * filp, int on);
 static void release_mem(struct tty_struct *tty, int idx);
-static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
 
 /**
  *	alloc_tty_struct	-	allocate a tty object
@@ -1110,17 +1110,17 @@ int tty_check_change(struct tty_struct * tty)
 {
 	if (current->signal->tty != tty)
 		return 0;
-	if (tty->pgrp <= 0) {
-		printk(KERN_WARNING "tty_check_change: tty->pgrp <= 0!\n");
+	if (!tty->pgrp) {
+		printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
 		return 0;
 	}
-	if (process_group(current) == tty->pgrp)
+	if (task_pgrp(current) == tty->pgrp)
 		return 0;
 	if (is_ignored(SIGTTOU))
 		return 0;
 	if (is_current_pgrp_orphaned())
 		return -EIO;
-	(void) kill_pg(process_group(current), SIGTTOU, 1);
+	(void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
 	return -ERESTARTSYS;
 }
 
@@ -1355,8 +1355,8 @@ static void do_tty_hangup(struct work_struct *work)
 	  tty_release is called */
 	
 	read_lock(&tasklist_lock);
-	if (tty->session > 0) {
-		do_each_task_pid(tty->session, PIDTYPE_SID, p) {
+	if (tty->session) {
+		do_each_pid_task(tty->session, PIDTYPE_SID, p) {
 			spin_lock_irq(&p->sighand->siglock);
 			if (p->signal->tty == tty)
 				p->signal->tty = NULL;
@@ -1366,16 +1366,17 @@ static void do_tty_hangup(struct work_struct *work)
 			}
 			__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
 			__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
-			if (tty->pgrp > 0)
-				p->signal->tty_old_pgrp = tty->pgrp;
+			put_pid(p->signal->tty_old_pgrp);  /* A noop */
+			if (tty->pgrp)
+				p->signal->tty_old_pgrp = get_pid(tty->pgrp);
 			spin_unlock_irq(&p->sighand->siglock);
-		} while_each_task_pid(tty->session, PIDTYPE_SID, p);
+		} while_each_pid_task(tty->session, PIDTYPE_SID, p);
 	}
 	read_unlock(&tasklist_lock);
 
 	tty->flags = 0;
-	tty->session = 0;
-	tty->pgrp = -1;
+	tty->session = NULL;
+	tty->pgrp = NULL;
 	tty->ctrl_status = 0;
 	/*
 	 *	If one of the devices matches a console pointer, we
@@ -1460,12 +1461,12 @@ int tty_hung_up_p(struct file * filp)
 
 EXPORT_SYMBOL(tty_hung_up_p);
 
-static void session_clear_tty(pid_t session)
+static void session_clear_tty(struct pid *session)
 {
 	struct task_struct *p;
-	do_each_task_pid(session, PIDTYPE_SID, p) {
+	do_each_pid_task(session, PIDTYPE_SID, p) {
 		proc_clear_tty(p);
-	} while_each_task_pid(session, PIDTYPE_SID, p);
+	} while_each_pid_task(session, PIDTYPE_SID, p);
 }
 
 /**
@@ -1495,48 +1496,54 @@ static void session_clear_tty(pid_t session)
 void disassociate_ctty(int on_exit)
 {
 	struct tty_struct *tty;
-	int tty_pgrp = -1;
+	struct pid *tty_pgrp = NULL;
 
 	lock_kernel();
 
 	mutex_lock(&tty_mutex);
 	tty = get_current_tty();
 	if (tty) {
-		tty_pgrp = tty->pgrp;
+		tty_pgrp = get_pid(tty->pgrp);
 		mutex_unlock(&tty_mutex);
 		/* XXX: here we race, there is nothing protecting tty */
 		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
 			tty_vhangup(tty);
 	} else if (on_exit) {
-		pid_t old_pgrp;
+		struct pid *old_pgrp;
 		spin_lock_irq(&current->sighand->siglock);
 		old_pgrp = current->signal->tty_old_pgrp;
-		current->signal->tty_old_pgrp = 0;
+		current->signal->tty_old_pgrp = NULL;
 		spin_unlock_irq(&current->sighand->siglock);
 		if (old_pgrp) {
-			kill_pg(old_pgrp, SIGHUP, on_exit);
-			kill_pg(old_pgrp, SIGCONT, on_exit);
+			kill_pgrp(old_pgrp, SIGHUP, on_exit);
+			kill_pgrp(old_pgrp, SIGCONT, on_exit);
+			put_pid(old_pgrp);
 		}
 		mutex_unlock(&tty_mutex);
 		unlock_kernel();	
 		return;
 	}
-	if (tty_pgrp > 0) {
-		kill_pg(tty_pgrp, SIGHUP, on_exit);
+	if (tty_pgrp) {
+		kill_pgrp(tty_pgrp, SIGHUP, on_exit);
 		if (!on_exit)
-			kill_pg(tty_pgrp, SIGCONT, on_exit);
+			kill_pgrp(tty_pgrp, SIGCONT, on_exit);
+		put_pid(tty_pgrp);
 	}
 
 	spin_lock_irq(&current->sighand->siglock);
+	tty_pgrp = current->signal->tty_old_pgrp;
 	current->signal->tty_old_pgrp = 0;
 	spin_unlock_irq(&current->sighand->siglock);
+	put_pid(tty_pgrp);
 
 	mutex_lock(&tty_mutex);
 	/* It is possible that do_tty_hangup has free'd this tty */
 	tty = get_current_tty();
 	if (tty) {
-		tty->session = 0;
-		tty->pgrp = 0;
+		put_pid(tty->session);
+		put_pid(tty->pgrp);
+		tty->session = NULL;
+		tty->pgrp = NULL;
 	} else {
 #ifdef TTY_DEBUG_HANGUP
 		printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
@@ -1547,7 +1554,7 @@ void disassociate_ctty(int on_exit)
 
 	/* Now clear signal->tty under the lock */
 	read_lock(&tasklist_lock);
-	session_clear_tty(process_session(current));
+	session_clear_tty(task_session(current));
 	read_unlock(&tasklist_lock);
 	unlock_kernel();
 }
@@ -2484,6 +2491,7 @@ static int tty_open(struct inode * inode, struct file * filp)
 	int index;
 	dev_t device = inode->i_rdev;
 	unsigned short saved_flags = filp->f_flags;
+	struct pid *old_pgrp;
 
 	nonseekable_open(inode, filp);
 	
@@ -2577,15 +2585,17 @@ got_driver:
 		goto retry_open;
 	}
 
+	old_pgrp = NULL;
 	mutex_lock(&tty_mutex);
 	spin_lock_irq(&current->sighand->siglock);
 	if (!noctty &&
 	    current->signal->leader &&
 	    !current->signal->tty &&
-	    tty->session == 0)
-		__proc_set_tty(current, tty);
+	    tty->session == NULL)
+		old_pgrp = __proc_set_tty(current, tty);
 	spin_unlock_irq(&current->sighand->siglock);
 	mutex_unlock(&tty_mutex);
+	put_pid(old_pgrp);
 	return 0;
 }
 
@@ -2724,9 +2734,18 @@ static int tty_fasync(int fd, struct file * filp, int on)
 		return retval;
 
 	if (on) {
+		enum pid_type type;
+		struct pid *pid;
 		if (!waitqueue_active(&tty->read_wait))
 			tty->minimum_to_wake = 1;
-		retval = f_setown(filp, (-tty->pgrp) ? : current->pid, 0);
+		if (tty->pgrp) {
+			pid = tty->pgrp;
+			type = PIDTYPE_PGID;
+		} else {
+			pid = task_pid(current);
+			type = PIDTYPE_PID;
+		}
+		retval = __f_setown(filp, pid, type, 0);
 		if (retval)
 			return retval;
 	} else {
@@ -2828,10 +2847,10 @@ static int tiocswinsz(struct tty_struct *tty

...

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[Message index]

		[PATCH 0/12] tty layer and misc struct pid conversions By: ebiederm on Wed, 13 December 2006 11:03
		[PATCH 1/12] tty: Make __proc_set_tty static. By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 2/12] tty: Clarify disassociate_ctty By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 3/12] tty: Fix the locking for signal->session in disassociate_ctty By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 4/12] signal: Use kill_pgrp not kill_pg in the sunos compatibility code. By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 5/12] signal: Rewrite kill_something_info so it uses newer helpers. By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 6/12] pid: Make session_of_pgrp use struct pid instead of pid_t. By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 7/12] pid: Use struct pid for talking about process groups in exit.c By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 8/12] pid: Replace is_orphaned_pgrp with is_current_pgrp_orphaned By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 9/12] tty: Update the tty layer to work with struct pid. By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 10/12] pid: Replace do/while_each_task_pid with do/while_each_pid_task By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 11/12] pid: Remove now unused do_each_task_pid and while_each_task_pid By: ebiederm on Wed, 13 December 2006 11:07
		[PATCH 12/12] pid: Remove the now unused kill_pg kill_pg_info and __kill_pg_info By: ebiederm on Wed, 13 December 2006 11:07
		Re: [PATCH 0/12] tty layer and misc struct pid conversions By: Andrew Morton on Wed, 13 December 2006 22:10
		Re: [PATCH 0/12] tty layer and misc struct pid conversions By: ebiederm on Thu, 14 December 2006 00:54

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