From: Peter Hurley <peter@hurleysoftware.com>
Date: Thu, 16 Oct 2014 17:51:30 +0000 (-0400)
Subject: tty: Fix high cpu load if tty is unreleaseable
X-Git-Tag: v3.2.65~49
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=069347b245ac0afe052f68e7f5ea734207f826f4;p=pandora-kernel.git

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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