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| author | Peter Hurley <peter@hurleysoftware.com> | 2014-10-16 13:51:30 -0400 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-11-13 19:03:00 +0100 |
| commit | 866f9fec24ee1dfa4a40e1d166b6ce3f4c3736de (patch) | |
| tree | ba9b4f966ebb6d530039ad342bf6dd341d4d4b3b /drivers/tty | |
| parent | 0277558a6cc692295cb568b22970c12db2587f9a (diff) | |
| download | lwn-866f9fec24ee1dfa4a40e1d166b6ce3f4c3736de.tar.gz lwn-866f9fec24ee1dfa4a40e1d166b6ce3f4c3736de.zip | |
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: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/tty_io.c | 7 |
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; } /* |