From: Peter Hurley <peter@hurleysoftware.com>
Date: Fri, 23 Jan 2015 17:16:53 +0000 (-0500)
Subject: Bluetooth: Fix nested sleeps
X-Git-Tag: omap-for-v4.1/prcm-dts-mfd-syscon-fix~134^2~73^2~43
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dfb2fae7cd0a1aa13610b11d54203bcd3893da07;p=pandora-kernel.git

Bluetooth: Fix nested sleeps

l2cap/rfcomm/sco_sock_accept() are wait loops which may acquire
sleeping locks. Since both wait loops and sleeping locks use
task_struct.state to sleep and wake, the nested sleeping locks
destroy the wait loop state.

Use the newly-minted wait_woken() and DEFINE_WAIT_FUNC() for the
wait loop. DEFINE_WAIT_FUNC() allows an alternate wake function
to be specified; in this case, the predefined scheduler function,
woken_wake_function(). This wait construct ensures wakeups will
not be missed without requiring the wait loop to set the
task state before condition evaluation. How this works:

 CPU 0                            |  CPU 1
                                  |
                                  | is <condition> set?
                                  | no
set <condition>                   |
                                  |
wake_up_interruptible             |
  woken_wake_function             |
    set WQ_FLAG_WOKEN             |
    try_to_wake_up                |
                                  | wait_woken
                                  |   set TASK_INTERRUPTIBLE
                                  |   WQ_FLAG_WOKEN? yes
                                  |   set TASK_RUNNING
                                  |
                                  | - loop -
				  |
				  | is <condition> set?
                                  | yes - exit wait loop

Fixes "do not call blocking ops when !TASK_RUNNING" warnings
in l2cap_sock_accept(), rfcomm_sock_accept() and sco_sock_accept().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
---

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