From: Philipp Reisner <philipp.reisner@linbit.com>
Date: Wed, 23 Jun 2010 09:20:05 +0000 (+0200)
Subject: drbd: Fixed a deadlock, probably only affected UP machines
X-Git-Tag: v2.6.37-rc1~167^2~59
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84dfb9f564208a0331131d1ab922382c7d61a553;p=pandora-kernel.git

drbd: Fixed a deadlock, probably only affected UP machines

After disconnect (most likely mdev->net_cnt == 0) and we are
still in an unstable state (!drbd_state_is_stable()). When we
get an IO request in drbd_get_max_buffers() (called from
__inc_ap_bio_cond(), called from inc_ap_bio()) we wake up
misc_wait. Misc_wait is also used in inc_ap_bio() to sleep
until the outcome of __inc_ap_bio_cond() changes. => Busy loop!

Solution: Have a dedicated wait queue for get_net_conf() and
put_net_conf().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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