Bluetooth: Fix sleeping function in RFCOMM within invalid context

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From: Linux Kernel Mailing List
Date: Wednesday, February 10, 2010 - 8:59 am

Gitweb:     http://git.kernel.org/linus/485f1eff73a7b932fd3abb0dfcf804e1a1f59025
Commit:     485f1eff73a7b932fd3abb0dfcf804e1a1f59025
Parent:     1038a00b458997661bcd0e780a24dc280a8841fc
Author:     Marcel Holtmann <marcel@holtmann.org>
AuthorDate: Wed Feb 3 15:52:18 2010 -0800
Committer:  Marcel Holtmann <marcel@holtmann.org>
CommitDate: Wed Feb 3 15:52:18 2010 -0800

    Bluetooth: Fix sleeping function in RFCOMM within invalid context
    
    With the commit 9e726b17422bade75fba94e625cd35fd1353e682 the
    rfcomm_session_put() gets accidentially called from a timeout
    callback and results in this:
    
    BUG: sleeping function called from invalid context at net/core/sock.c:1897
    in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper
    Pid: 0, comm: swapper Tainted: P           2.6.32 #31
    Call Trace:
     <IRQ>  [<ffffffff81036455>] __might_sleep+0xf8/0xfa
     [<ffffffff8138ef1d>] lock_sock_nested+0x29/0xc4
     [<ffffffffa03921b3>] lock_sock+0xb/0xd [l2cap]
     [<ffffffffa03948e6>] l2cap_sock_shutdown+0x1c/0x76 [l2cap]
     [<ffffffff8106adea>] ? clockevents_program_event+0x75/0x7e
     [<ffffffff8106bea2>] ? tick_dev_program_event+0x37/0xa5
     [<ffffffffa0394967>] l2cap_sock_release+0x27/0x67 [l2cap]
     [<ffffffff8138c971>] sock_release+0x1a/0x67
     [<ffffffffa03d2492>] rfcomm_session_del+0x34/0x53 [rfcomm]
     [<ffffffffa03d24c5>] rfcomm_session_put+0x14/0x16 [rfcomm]
     [<ffffffffa03d28b4>] rfcomm_session_timeout+0xe/0x1a [rfcomm]
     [<ffffffff810554a8>] run_timer_softirq+0x1e2/0x29a
     [<ffffffffa03d28a6>] ? rfcomm_session_timeout+0x0/0x1a [rfcomm]
     [<ffffffff8104e0f6>] __do_softirq+0xfe/0x1c5
     [<ffffffff8100e8ce>] ? timer_interrupt+0x1a/0x21
     [<ffffffff8100cc4c>] call_softirq+0x1c/0x28
     [<ffffffff8100e05b>] do_softirq+0x33/0x6b
     [<ffffffff8104daf6>] irq_exit+0x36/0x85
     [<ffffffff8100d7a9>] do_IRQ+0xa6/0xbd
     [<ffffffff8100c493>] ret_from_intr+0x0/0xa
     <EOI>  [<ffffffff812585b3>] ? acpi_idle_enter_bm+0x269/0x294
     [<ffffffff812585a9>] ? acpi_idle_enter_bm+0x25f/0x294
     [<ffffffff81373ddc>] ? cpuidle_idle_call+0x97/0x107
     [<ffffffff8100aca0>] ? cpu_idle+0x53/0xaa
     [<ffffffff81429006>] ? rest_init+0x7a/0x7c
     [<ffffffff8177bc8c>] ? start_kernel+0x389/0x394
     [<ffffffff8177b29c>] ? x86_64_start_reservations+0xac/0xb0
     [<ffffffff8177b384>] ? x86_64_start_kernel+0xe4/0xeb
    
    To fix this, the rfcomm_session_put() needs to be moved out of
    rfcomm_session_timeout() into rfcomm_process_sessions(). In that
    context it is perfectly fine to sleep and disconnect the socket.
    
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Tested-by: David John <davidjon@xenontk.org>
---
 net/bluetooth/rfcomm/core.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index fc5ee32..2b50637 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -252,7 +252,6 @@ static void rfcomm_session_timeout(unsigned long arg)
 	BT_DBG("session %p state %ld", s, s->state);
 
 	set_bit(RFCOMM_TIMED_OUT, &s->flags);
-	rfcomm_session_put(s);
 	rfcomm_schedule(RFCOMM_SCHED_TIMEO);
 }
 
@@ -1920,6 +1919,7 @@ static inline void rfcomm_process_sessions(void)
 		if (test_and_clear_bit(RFCOMM_TIMED_OUT, &s->flags)) {
 			s->state = BT_DISCONN;
 			rfcomm_send_disc(s, 0);
+			rfcomm_session_put(s);
 			continue;
 		}
 
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Bluetooth: Fix sleeping function in RFCOMM within invalid ..., Linux Kernel Mailing ..., (Wed Feb 10, 8:59 am)