linux-kernel - [PATCH -rt] powerpc/qeic: fix sleeping in atomic context

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Date:	Tue, 26 Aug 2008 21:58:55 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>
Cc:	Daniel Walker <dwalker@...sta.com>,
	Timur Tabi <timur@...escale.com>, linux-kernel@...r.kernel.org,
	linuxppc-dev@...abs.org
Subject: [PATCH -rt] powerpc/qeic: fix sleeping in atomic context

Cascade interrupts do not use threads, thus handlers are called
with interrupts disabled. This means that we must not grab regular
spinlocks, since they might sleep:

BUG: sleeping function called from invalid context swapper(0) at kernel/rtmutex.c:743
in_atomic():1 [00010002], irqs_disabled():1
Call Trace:
[c0353e00] [c0008a04] show_stack+0x4c/0x1ac (unreliable)
[c0353e40] [c001ca18] __might_sleep+0xc0/0x108
[c0353e50] [c0254218] __rt_spin_lock+0x30/0xa0
[c0353e60] [c0018238] qe_ic_mask_irq+0x58/0xc4
[c0353e80] [c0057bc8] handle_level_irq+0x40/0x178
[c0353ea0] [c001a5c0] qe_ic_cascade_low_ipic+0x50/0x68
[c0353eb0] [c00066d0] do_IRQ+0x9c/0xc0
[c0353ec0] [c001167c] ret_from_except+0x0/0x14
--- Exception: 501 at cpu_idle+0xa0/0x104
    LR = cpu_idle+0xa0/0x104
[c0353f80] [c0009b5c] cpu_idle+0x50/0x104 (unreliable)
[c0353fa0] [c0256088] _etext+0x88/0x9c
[c0353fc0] [c0304af8] start_kernel+0x1c4/0x244
[c0353ff0] [00003438] 0x3438

To fix the issue we should use raw spin lock.

Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
---

Note, the patch is for -rt tree only.

 arch/powerpc/sysdev/qe_lib/qe_ic.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/sysdev/qe_lib/qe_ic.c b/arch/powerpc/sysdev/qe_lib/qe_ic.c
index f59444d..a30169c 100644
--- a/arch/powerpc/sysdev/qe_lib/qe_ic.c
+++ b/arch/powerpc/sysdev/qe_lib/qe_ic.c
@@ -33,7 +33,7 @@
 
 #include "qe_ic.h"
 
-static DEFINE_SPINLOCK(qe_ic_lock);
+static DEFINE_RAW_SPINLOCK(qe_ic_lock);
 
 static struct qe_ic_info qe_ic_info[] = {
 	[1] = {
-- 
1.5.6.3
--
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