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From: Arnd Bergmann <arnd@arndb.de>
To: Alan Cox <alan@linux.intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
	"Greg Kroah-Hartman" <gregkh@suse.de>
Subject: possible locking bug in tty_open
Date: Sun, 2 May 2010 22:47:33 +0200	[thread overview]
Message-ID: <201005022247.33857.arnd@arndb.de> (raw)

While playing some more with my TTY BKL patches, I stumbled over
what looks like a bug in tty_open, introduced in e8c6210 
"tty: push the BKL down into the handlers a bit":

After the "retry_open:" label, we first get the tty_mutex
and then the BKL. However a the end of tty_open, we jump
back to retry_open with the BKL still held. If we run into
this case, the tty_open function will be left with the BKL
still held.

It may be impossible to actually trigger this bug, because
the path is only taken if a tty driver open function returns
-ERESTARTSYS without setting signal_pending().

	Arnd

             reply	other threads:[~2010-05-02 20:47 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-02 20:47 Arnd Bergmann [this message]
2010-05-04  9:43 ` possible locking bug in tty_open Alan Cox
2010-05-04 19:42 ` Alan Cox
2010-05-04 20:26   ` Arnd Bergmann

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