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authorPeter Hurley <peter@hurleysoftware.com>2014-10-16 13:51:30 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-14 09:00:10 -0800
commit2ceee507fac81179f206691fec3163839c5dd5d8 (patch)
treed14bb14c2ef0f06248c73c3a7128707f971df174
parent905290c5f3143eb78683bb24ec3f434fc0abb48b (diff)
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tty: Fix high cpu load if tty is unreleaseable
commit 37b164578826406a173ca7c20d9ba7430134d23e upstream. Kernel oops can cause the tty to be unreleaseable (for example, if n_tty_read() crashes while on the read_wait queue). This will cause tty_release() to endlessly loop without sleeping. Use a killable sleep timeout which grows by 2n+1 jiffies over the interval [0, 120 secs.) and then jumps to forever (but still killable). NB: killable just allows for the task to be rewoken manually, not to be terminated. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/tty_io.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index d3448a90f0f9..25d07412e08e 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1701,6 +1701,7 @@ int tty_release(struct inode *inode, struct file *filp)
int pty_master, tty_closing, o_tty_closing, do_sleep;
int idx;
char buf[64];
+ long timeout = 0;
if (tty_paranoia_check(tty, inode, __func__))
return 0;
@@ -1785,7 +1786,11 @@ int tty_release(struct inode *inode, struct file *filp)
__func__, tty_name(tty, buf));
tty_unlock_pair(tty, o_tty);
mutex_unlock(&tty_mutex);
- schedule();
+ schedule_timeout_killable(timeout);
+ if (timeout < 120 * HZ)
+ timeout = 2 * timeout + 1;
+ else
+ timeout = MAX_SCHEDULE_TIMEOUT;
}
/*