77 lines
2.3 KiB
Diff
77 lines
2.3 KiB
Diff
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From 9e88e8b9915b5e067507a087437d80e6a133d612 Mon Sep 17 00:00:00 2001
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From: Jiri Slaby <jslaby@suse.cz>
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Date: Sat, 27 Nov 2010 16:06:46 +0100
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Subject: [PATCH 1/1] TTY: open/hangup race fixup
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Signed-off-by: Jiri Slaby <jslaby@suse.cz>
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---
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drivers/tty/tty_io.c | 10 +++++++++-
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include/linux/tty.h | 1 +
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2 files changed, 10 insertions(+), 1 deletions(-)
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diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
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index 878f6d6..35480dd 100644
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--- a/drivers/tty/tty_io.c
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+++ b/drivers/tty/tty_io.c
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@@ -559,6 +559,9 @@ void __tty_hangup(struct tty_struct *tty)
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tty_lock();
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+ /* some functions below drop BTM, so we need this bit */
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+ set_bit(TTY_HUPPING, &tty->flags);
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+
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/* inuse_filps is protected by the single tty lock,
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this really needs to change if we want to flush the
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workqueue with the lock held */
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@@ -578,6 +581,10 @@ void __tty_hangup(struct tty_struct *tty)
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}
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spin_unlock(&tty_files_lock);
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+ /*
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+ * it drops BTM and thus races with reopen
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+ * we protect the race by TTY_HUPPING
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+ */
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tty_ldisc_hangup(tty);
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read_lock(&tasklist_lock);
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@@ -615,7 +622,6 @@ void __tty_hangup(struct tty_struct *tty)
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tty->session = NULL;
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tty->pgrp = NULL;
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tty->ctrl_status = 0;
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- set_bit(TTY_HUPPED, &tty->flags);
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spin_unlock_irqrestore(&tty->ctrl_lock, flags);
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/* Account for the p->signal references we killed */
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@@ -641,6 +647,7 @@ void __tty_hangup(struct tty_struct *tty)
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* can't yet guarantee all that.
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*/
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set_bit(TTY_HUPPED, &tty->flags);
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+ clear_bit(TTY_HUPPING, &tty->flags);
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tty_ldisc_enable(tty);
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tty_unlock();
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@@ -1311,6 +1318,7 @@ static int tty_reopen(struct tty_struct *tty)
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struct tty_driver *driver = tty->driver;
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if (test_bit(TTY_CLOSING, &tty->flags) ||
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+ test_bit(TTY_HUPPING, &tty->flags) ||
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test_bit(TTY_LDISC_CHANGING, &tty->flags))
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return -EIO;
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diff --git a/include/linux/tty.h b/include/linux/tty.h
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index 032d79f..54e4eaa 100644
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--- a/include/linux/tty.h
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+++ b/include/linux/tty.h
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@@ -366,6 +366,7 @@ struct tty_file_private {
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#define TTY_HUPPED 18 /* Post driver->hangup() */
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#define TTY_FLUSHING 19 /* Flushing to ldisc in progress */
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#define TTY_FLUSHPENDING 20 /* Queued buffer flush pending */
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+#define TTY_HUPPING 21 /* ->hangup() in progress */
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#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
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--
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1.7.3.1
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