tty patches merged with linus and 2.6.31-rc5-git3 resync

author: Greg Kroah-Hartman <gregkh@suse.de> 2009-08-05 09:54:26 -0700
committer: Greg Kroah-Hartman <gregkh@suse.de> 2009-08-05 09:54:26 -0700
commit: 4e35c788e2b0f00702521c5b19f125df5be9454e (patch)
tree: fc855b29875ed9696fa364de5c95a028331fdd97
parent: 0f231910e326b1bc7c33e371eb0b2e16e149ffd8 (diff)
download: patches-4e35c788e2b0f00702521c5b19f125df5be9454e.tar.gz
5 files changed, 1 insertions, 489 deletions
diff --git a/series b/series
index 37c28797cc4a81..823dff8ba431c2 100644
--- a/series
+++ b/series
@@ -51,9 +51,6 @@ driver-core/driver-core-devtmpfs-driver-core-maintained-dev-tmpfs.patch
 #################################
 # TTY patches for after 2.6.31 is out
 #################################
-tty/tty-ldisc-make-refcount-be-atomic_t-users-count.patch
-tty/tty-ldisc-turn-ldisc-user-count-into-a-proper-refcount.patch
-tty/tty-ldisc-be-more-careful-in-put_ldisc-locking.patch
 tty/tty-ldisc-make-proc-tty-ldiscs-use-ldisc_ops-instead-of-ldiscs.patch
 tty/tty-ldisc-get-rid-of-tty_ldisc_try_get-helper-function.patch
 
diff --git a/tty/tty-ldisc-be-more-careful-in-put_ldisc-locking.patch b/tty/tty-ldisc-be-more-careful-in-put_ldisc-locking.patch
deleted file mode 100644
index a34cefd7d7767e..00000000000000
--- a/tty/tty-ldisc-be-more-careful-in-put_ldisc-locking.patch
+++ /dev/null
@@ -1,60 +0,0 @@
-From torvalds@linux-foundation.org  Mon Aug  3 15:07:29 2009
-From: Linus Torvalds <torvalds@linux-foundation.org>
-Date: Mon, 3 Aug 2009 14:54:56 -0700 (PDT)
-Subject: tty-ldisc: be more careful in 'put_ldisc' locking
-To: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>, Greg KH <greg@kroah.com>
-Message-ID: <alpine.LFD.2.01.0908031448540.3208@localhost.localdomain>
-
-
-Use 'atomic_dec_and_lock()' to make sure that we always hold the
-tty_ldisc_lock when the ldisc count goes to zero. That way we can never
-race against 'tty_ldisc_try()' increasing the count again.
-
-Reported-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-Tested-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
-Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
----
- drivers/char/tty_ldisc.c |   17 ++++++++++++-----
- 1 file changed, 12 insertions(+), 5 deletions(-)
-
---- a/drivers/char/tty_ldisc.c
-+++ b/drivers/char/tty_ldisc.c
-@@ -55,25 +55,32 @@ static inline struct tty_ldisc *get_ldis
- 	return ld;
- }
- 
--static inline void put_ldisc(struct tty_ldisc *ld)
-+static void put_ldisc(struct tty_ldisc *ld)
- {
-+	unsigned long flags;
-+
- 	if (WARN_ON_ONCE(!ld))
- 		return;
- 
- 	/*
- 	 * If this is the last user, free the ldisc, and
- 	 * release the ldisc ops.
-+	 *
-+	 * We really want an "atomic_dec_and_lock_irqsave()",
-+	 * but we don't have it, so this does it by hand.
- 	 */
--	if (atomic_dec_and_test(&ld->users)) {
--		unsigned long flags;
-+	local_irq_save(flags);
-+	if (atomic_dec_and_lock(&ld->users, &tty_ldisc_lock)) {
- 		struct tty_ldisc_ops *ldo = ld->ops;
- 
--		kfree(ld);
--		spin_lock_irqsave(&tty_ldisc_lock, flags);
- 		ldo->refcount--;
- 		module_put(ldo->owner);
- 		spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-+
-+		kfree(ld);
-+		return;
- 	}
-+	local_irq_restore(flags);
- }
- 
- /**
diff --git a/tty/tty-ldisc-make-refcount-be-atomic_t-users-count.patch b/tty/tty-ldisc-make-refcount-be-atomic_t-users-count.patch
deleted file mode 100644
index c46da268f0d22a..00000000000000
--- a/tty/tty-ldisc-make-refcount-be-atomic_t-users-count.patch
+++ /dev/null
@@ -1,111 +0,0 @@
-From torvalds@linux-foundation.org  Mon Aug  3 14:34:51 2009
-From: Linus Torvalds <torvalds@linux-foundation.org>
-Date: Mon, 3 Aug 2009 10:58:29 -0700 (PDT)
-Subject: tty-ldisc: make refcount be atomic_t 'users' count
-To: Alan Cox <alan@lxorguk.ukuu.org.uk>
-Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>, Sergey Senozhatsky <sergey.senozhatsky@mail.by>, Greg KH <greg@kroah.com>
-Message-ID: <alpine.LFD.2.01.0908031055400.3208@localhost.localdomain>
-
-From: Linus Torvalds <torvalds@linux-foundation.org>
-
-This is pure preparation of changing the ldisc reference counting to be
-a true refcount that defines the lifetime of the ldisc.  But this is a
-purely syntactic change for now to make the next steps easier.
-
-This patch should make no semantic changes at all. But I wanted to make
-the ldisc refcount be an atomic (I will be touching it without locks
-soon enough), and I wanted to rename it so that there isn't quite as
-much confusion between 'ldo->refcount' (ldisk operations refcount) and
-'ld->refcount' (ldisc refcount itself) in the same file.
-
-So it's now an atomic 'ld->users' count. It still starts at zero,
-despite having a reference from 'tty->ldisc', but that will change once
-we turn it into a _real_ refcount.
-
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-Tested-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
-Tested-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
-Acked-by: Alan Cox <alan@linux.intel.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-
----
- drivers/char/tty_ldisc.c  |   18 ++++++++----------
- include/linux/tty_ldisc.h |    2 +-
- 2 files changed, 9 insertions(+), 11 deletions(-)
-
---- a/drivers/char/tty_ldisc.c
-+++ b/drivers/char/tty_ldisc.c
-@@ -142,7 +142,7 @@ static struct tty_ldisc *tty_ldisc_try_g
- 			/* lock it */
- 			ldops->refcount++;
- 			ld->ops = ldops;
--			ld->refcount = 0;
-+			atomic_set(&ld->users, 0);
- 			err = 0;
- 		}
- 	}
-@@ -206,7 +206,7 @@ static void tty_ldisc_put(struct tty_ldi
- 	ldo->refcount--;
- 	module_put(ldo->owner);
- 	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
--	WARN_ON(ld->refcount);
-+	WARN_ON(atomic_read(&ld->users));
- 	kfree(ld);
- }
- 
-@@ -297,7 +297,7 @@ static int tty_ldisc_try(struct tty_stru
- 	spin_lock_irqsave(&tty_ldisc_lock, flags);
- 	ld = tty->ldisc;
- 	if (test_bit(TTY_LDISC, &tty->flags)) {
--		ld->refcount++;
-+		atomic_inc(&ld->users);
- 		ret = 1;
- 	}
- 	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-@@ -324,7 +324,7 @@ struct tty_ldisc *tty_ldisc_ref_wait(str
- {
- 	/* wait_event is a macro */
- 	wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
--	WARN_ON(tty->ldisc->refcount == 0);
-+	WARN_ON(atomic_read(&tty->ldisc->users) == 0);
- 	return tty->ldisc;
- }
- EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
-@@ -365,11 +365,9 @@ void tty_ldisc_deref(struct tty_ldisc *l
- 	BUG_ON(ld == NULL);
- 
- 	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	if (ld->refcount == 0)
-+	if (atomic_read(&ld->users) == 0)
- 		printk(KERN_ERR "tty_ldisc_deref: no references.\n");
--	else
--		ld->refcount--;
--	if (ld->refcount == 0)
-+	else if (atomic_dec_and_test(&ld->users))
- 		wake_up(&tty_ldisc_wait);
- 	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
- }
-@@ -536,10 +534,10 @@ static int tty_ldisc_wait_idle(struct tt
- {
- 	unsigned long flags;
- 	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	while (tty->ldisc->refcount) {
-+	while (atomic_read(&tty->ldisc->users)) {
- 		spin_unlock_irqrestore(&tty_ldisc_lock, flags);
- 		if (wait_event_timeout(tty_ldisc_wait,
--				tty->ldisc->refcount == 0, 5 * HZ) == 0)
-+				atomic_read(&tty->ldisc->users) == 0, 5 * HZ) == 0)
- 			return -EBUSY;
- 		spin_lock_irqsave(&tty_ldisc_lock, flags);
- 	}
---- a/include/linux/tty_ldisc.h
-+++ b/include/linux/tty_ldisc.h
-@@ -144,7 +144,7 @@ struct tty_ldisc_ops {
- 
- struct tty_ldisc {
- 	struct tty_ldisc_ops *ops;
--	int refcount;
-+	atomic_t users;
- };
- 
- #define TTY_LDISC_MAGIC	0x5403
diff --git a/tty/tty-ldisc-turn-ldisc-user-count-into-a-proper-refcount.patch b/tty/tty-ldisc-turn-ldisc-user-count-into-a-proper-refcount.patch
deleted file mode 100644
index fb1247b678d498..00000000000000
--- a/tty/tty-ldisc-turn-ldisc-user-count-into-a-proper-refcount.patch
+++ /dev/null
@@ -1,314 +0,0 @@
-From torvalds@linux-foundation.org  Mon Aug  3 14:36:18 2009
-From: Linus Torvalds <torvalds@linux-foundation.org>
-Date: Mon, 3 Aug 2009 11:11:19 -0700 (PDT)
-Subject: tty-ldisc: turn ldisc user count into a proper refcount
-To: Alan Cox <alan@lxorguk.ukuu.org.uk>
-Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>, Sergey Senozhatsky <sergey.senozhatsky@mail.by>, Greg KH <greg@kroah.com>
-Message-ID: <alpine.LFD.2.01.0908031058330.3208@localhost.localdomain>
-
-
-From: Linus Torvalds <torvalds@linux-foundation.org>
-
-By using the user count for the actual lifetime rules, we can get rid of
-the silly "wait_for_idle" logic, because any busy ldisc will
-automatically stay around until the last user releases it.  This avoids
-a host of odd issues, and simplifies the code.
-
-So now, when the last ldisc reference is dropped, we just release the
-ldisc operations struct reference, and free the ldisc.
-
-It looks obvious enough, and it does work for me, but the counting
-_could_ be off. It probably isn't (bad counting in the new version would
-generally imply that the old code did something really bad, like free an
-ldisc with a non-zero count), but it does need some testing, and
-preferably somebody looking at it.
-
-With this change, both 'tty_ldisc_put()' and 'tty_ldisc_deref()' are
-just aliases for the new ref-counting 'put_ldisc()'. Both of them
-decrement the ldisc user count and free it if it goes down to zero.
-They're identical functions, in other words.
-
-But the reason they still exist as sepate functions is that one of them
-was exported (tty_ldisc_deref) and had a stupid name (so I don't want to
-use it as the main name), and the other one was used in multiple places
-(and I didn't want to make the patch larger just to rename the users).
-
-In addition to the refcounting, I did do some minimal cleanup. For
-example, now "tty_ldisc_try()" actually returns the ldisc it got under
-the lock, rather than returning true/false and then the caller would
-look up the ldisc again (now without the protection of the lock).
-
-That said, there's tons of dubious use of 'tty->ldisc' without obviously
-proper locking or refcounting left. I expressly did _not_ want to try to
-fix it all, keeping the patch minimal. There may or may not be bugs in
-that kind of code, but they wouldn't be _new_ bugs.
-
-That said, even if the bugs aren't new, the timing and lifetime will
-change. For example, some silly code may depend on the 'tty->ldisc'
-pointer not changing because they hold a refcount on the 'ldisc'. And
-that's no longer true - if you hold a ref on the ldisc, the 'ldisc'
-itself is safe, but tty->ldisc may change.
-
-So the proper locking (remains) to hold tty->ldisc_mutex if you expect
-tty->ldisc to be stable. That's not really a _new_ rule, but it's an
-example of something that the old code might have unintentionally
-depended on and hidden bugs.
-
-Whatever. The patch _looks_ sensible to me. The only users of
-ldisc->users are:
- - get_ldisc() - atomically increment the count
-
- - put_ldisc() - atomically decrements the count and releases if zero
-
- - tty_ldisc_try_get() - creates the ldisc, and sets the count to 1.
-   The ldisc should then either be released, or be attached to a tty.
-
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-Tested-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
-Tested-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
-Acked-by: Alan Cox <alan@linux.intel.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-
----
- drivers/char/tty_ldisc.c |  143 +++++++++++++++--------------------------------
- 1 file changed, 46 insertions(+), 97 deletions(-)
-
---- a/drivers/char/tty_ldisc.c
-+++ b/drivers/char/tty_ldisc.c
-@@ -48,6 +48,34 @@ static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc
- /* Line disc dispatch table */
- static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
- 
-+static inline struct tty_ldisc *get_ldisc(struct tty_ldisc *ld)
-+{
-+	if (ld)
-+		atomic_inc(&ld->users);
-+	return ld;
-+}
-+
-+static inline void put_ldisc(struct tty_ldisc *ld)
-+{
-+	if (WARN_ON_ONCE(!ld))
-+		return;
-+
-+	/*
-+	 * If this is the last user, free the ldisc, and
-+	 * release the ldisc ops.
-+	 */
-+	if (atomic_dec_and_test(&ld->users)) {
-+		unsigned long flags;
-+		struct tty_ldisc_ops *ldo = ld->ops;
-+
-+		kfree(ld);
-+		spin_lock_irqsave(&tty_ldisc_lock, flags);
-+		ldo->refcount--;
-+		module_put(ldo->owner);
-+		spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-+	}
-+}
-+
- /**
-  *	tty_register_ldisc	-	install a line discipline
-  *	@disc: ldisc number
-@@ -142,7 +170,7 @@ static struct tty_ldisc *tty_ldisc_try_g
- 			/* lock it */
- 			ldops->refcount++;
- 			ld->ops = ldops;
--			atomic_set(&ld->users, 0);
-+			atomic_set(&ld->users, 1);
- 			err = 0;
- 		}
- 	}
-@@ -181,35 +209,6 @@ static struct tty_ldisc *tty_ldisc_get(i
- 	return ld;
- }
- 
--/**
-- *	tty_ldisc_put		-	drop ldisc reference
-- *	@ld: ldisc
-- *
-- *	Drop a reference to a line discipline. Manage refcounts and
-- *	module usage counts. Free the ldisc once the recount hits zero.
-- *
-- *	Locking:
-- *		takes tty_ldisc_lock to guard against ldisc races
-- */
--
--static void tty_ldisc_put(struct tty_ldisc *ld)
--{
--	unsigned long flags;
--	int disc = ld->ops->num;
--	struct tty_ldisc_ops *ldo;
--
--	BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
--
--	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	ldo = tty_ldiscs[disc];
--	BUG_ON(ldo->refcount == 0);
--	ldo->refcount--;
--	module_put(ldo->owner);
--	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
--	WARN_ON(atomic_read(&ld->users));
--	kfree(ld);
--}
--
- static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos)
- {
- 	return (*pos < NR_LDISCS) ? pos : NULL;
-@@ -234,7 +233,7 @@ static int tty_ldiscs_seq_show(struct se
- 	if (IS_ERR(ld))
- 		return 0;
- 	seq_printf(m, "%-10s %2d\n", ld->ops->name ? ld->ops->name : "???", i);
--	tty_ldisc_put(ld);
-+	put_ldisc(ld);
- 	return 0;
- }
- 
-@@ -288,20 +287,17 @@ static void tty_ldisc_assign(struct tty_
-  *	Locking: takes tty_ldisc_lock
-  */
- 
--static int tty_ldisc_try(struct tty_struct *tty)
-+static struct tty_ldisc *tty_ldisc_try(struct tty_struct *tty)
- {
- 	unsigned long flags;
- 	struct tty_ldisc *ld;
--	int ret = 0;
- 
- 	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	ld = tty->ldisc;
--	if (test_bit(TTY_LDISC, &tty->flags)) {
--		atomic_inc(&ld->users);
--		ret = 1;
--	}
-+	ld = NULL;
-+	if (test_bit(TTY_LDISC, &tty->flags))
-+		ld = get_ldisc(tty->ldisc);
- 	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
--	return ret;
-+	return ld;
- }
- 
- /**
-@@ -322,10 +318,11 @@ static int tty_ldisc_try(struct tty_stru
- 
- struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
- {
-+	struct tty_ldisc *ld;
-+
- 	/* wait_event is a macro */
--	wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
--	WARN_ON(atomic_read(&tty->ldisc->users) == 0);
--	return tty->ldisc;
-+	wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL);
-+	return ld;
- }
- EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
- 
-@@ -342,9 +339,7 @@ EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
- 
- struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
- {
--	if (tty_ldisc_try(tty))
--		return tty->ldisc;
--	return NULL;
-+	return tty_ldisc_try(tty);
- }
- EXPORT_SYMBOL_GPL(tty_ldisc_ref);
- 
-@@ -360,19 +355,15 @@ EXPORT_SYMBOL_GPL(tty_ldisc_ref);
- 
- void tty_ldisc_deref(struct tty_ldisc *ld)
- {
--	unsigned long flags;
--
--	BUG_ON(ld == NULL);
--
--	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	if (atomic_read(&ld->users) == 0)
--		printk(KERN_ERR "tty_ldisc_deref: no references.\n");
--	else if (atomic_dec_and_test(&ld->users))
--		wake_up(&tty_ldisc_wait);
--	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-+	put_ldisc(ld);
- }
- EXPORT_SYMBOL_GPL(tty_ldisc_deref);
- 
-+static inline void tty_ldisc_put(struct tty_ldisc *ld)
-+{
-+	put_ldisc(ld);
-+}
-+
- /**
-  *	tty_ldisc_enable	-	allow ldisc use
-  *	@tty: terminal to activate ldisc on
-@@ -521,31 +512,6 @@ static int tty_ldisc_halt(struct tty_str
- }
- 
- /**
-- *	tty_ldisc_wait_idle	-	wait for the ldisc to become idle
-- *	@tty: tty to wait for
-- *
-- *	Wait for the line discipline to become idle. The discipline must
-- *	have been halted for this to guarantee it remains idle.
-- *
-- *	tty_ldisc_lock protects the ref counts currently.
-- */
--
--static int tty_ldisc_wait_idle(struct tty_struct *tty)
--{
--	unsigned long flags;
--	spin_lock_irqsave(&tty_ldisc_lock, flags);
--	while (atomic_read(&tty->ldisc->users)) {
--		spin_unlock_irqrestore(&tty_ldisc_lock, flags);
--		if (wait_event_timeout(tty_ldisc_wait,
--				atomic_read(&tty->ldisc->users) == 0, 5 * HZ) == 0)
--			return -EBUSY;
--		spin_lock_irqsave(&tty_ldisc_lock, flags);
--	}
--	spin_unlock_irqrestore(&tty_ldisc_lock, flags);
--	return 0;
--}
--
--/**
-  *	tty_set_ldisc		-	set line discipline
-  *	@tty: the terminal to set
-  *	@ldisc: the line discipline
-@@ -640,14 +606,6 @@ int tty_set_ldisc(struct tty_struct *tty
- 
- 	flush_scheduled_work();
- 
--	/* Let any existing reference holders finish */
--	retval = tty_ldisc_wait_idle(tty);
--	if (retval < 0) {
--		clear_bit(TTY_LDISC_CHANGING, &tty->flags);
--		tty_ldisc_put(new_ldisc);
--		return retval;
--	}
--
- 	mutex_lock(&tty->ldisc_mutex);
- 	if (test_bit(TTY_HUPPED, &tty->flags)) {
- 		/* We were raced by the hangup method. It will have stomped
-@@ -793,7 +751,6 @@ void tty_ldisc_hangup(struct tty_struct 
- 		if (tty->ldisc) {	/* Not yet closed */
- 			/* Switch back to N_TTY */
- 			tty_ldisc_halt(tty);
--			tty_ldisc_wait_idle(tty);
- 			tty_ldisc_reinit(tty);
- 			/* At this point we have a closed ldisc and we want to
- 			   reopen it. We could defer this to the next open but
-@@ -858,14 +815,6 @@ void tty_ldisc_release(struct tty_struct
- 	tty_ldisc_halt(tty);
- 	flush_scheduled_work();
- 
--	/*
--	 * Wait for any short term users (we know they are just driver
--	 * side waiters as the file is closing so user count on the file
--	 * side is zero.
--	 */
--
--	tty_ldisc_wait_idle(tty);
--
- 	mutex_lock(&tty->ldisc_mutex);
- 	/*
- 	 * Now kill off the ldisc
diff --git a/version b/version
index 9918e272f430ce..66ae3554c60c6d 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-2.6.31-rc5
+2.6.31-rc5-git3
author	Greg Kroah-Hartman <gregkh@suse.de>	2009-08-05 09:54:26 -0700
committer	Greg Kroah-Hartman <gregkh@suse.de>	2009-08-05 09:54:26 -0700
commit	4e35c788e2b0f00702521c5b19f125df5be9454e (patch)
tree	fc855b29875ed9696fa364de5c95a028331fdd97
parent	0f231910e326b1bc7c33e371eb0b2e16e149ffd8 (diff)
download	patches-4e35c788e2b0f00702521c5b19f125df5be9454e.tar.gz