From: Steven Rostedt <rostedt@goodmis.org>
To: Pratyush Anand <panand@redhat.com>
Cc: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
stable-rt@vger.kernel.org, Yang Shi <yang.shi@linaro.org>
Subject: Re: [PATCH RT 07/17] arm64: replace read_lock to rcu lock in call_step_hook
Date: Thu, 3 Mar 2016 09:21:24 -0500 [thread overview]
Message-ID: <20160303092124.7721ea80@gandalf.local.home> (raw)
In-Reply-To: <20160303091250.09034e47@gandalf.local.home>
On Thu, 3 Mar 2016 09:12:50 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:
> > I think, this got wrong during backporting, no?
> > Should have been
> > -DEFINE_RWLOCK(step_hook_lock);
> >
>
Below is the new patch.
Total -rc2 patch:
https://www.kernel.org/pub/linux/kernel/projects/rt/3.14/patch-3.14.61-rt64-rc2.patch.xz
Incremental patch:
https://www.kernel.org/pub/linux/kernel/projects/rt/3.14/incr/patch-3.14.61-rt63-rt64-rc2.patch.xz
-- Steve
>From e6b4b1b36de0e1dd5c47b9856938f7247208ff0f Mon Sep 17 00:00:00 2001
Date: Mon, 8 Feb 2016 14:49:24 -0800
Subject: arm64: replace read_lock to rcu lock in call_step_hook
3.14.61-rt64-rc2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Yang Shi <yang.shi@linaro.org>
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
in_atomic(): 1, irqs_disabled(): 128, pid: 383, name: sh
Preemption disabled at:[<ffff800000124c18>] kgdb_cpu_enter+0x158/0x6b8
CPU: 3 PID: 383 Comm: sh Tainted: G W 4.1.13-rt13 #2
Hardware name: Freescale Layerscape 2085a RDB Board (DT)
Call trace:
[<ffff8000000885e8>] dump_backtrace+0x0/0x128
[<ffff800000088734>] show_stack+0x24/0x30
[<ffff80000079a7c4>] dump_stack+0x80/0xa0
[<ffff8000000bd324>] ___might_sleep+0x18c/0x1a0
[<ffff8000007a20ac>] __rt_spin_lock+0x2c/0x40
[<ffff8000007a2268>] rt_read_lock+0x40/0x58
[<ffff800000085328>] single_step_handler+0x38/0xd8
[<ffff800000082368>] do_debug_exception+0x58/0xb8
Exception stack(0xffff80834a1e7c80 to 0xffff80834a1e7da0)
7c80: ffffff9c ffffffff 92c23ba0 0000ffff 4a1e7e40 ffff8083 001bfcc4 ffff8000
7ca0: f2000400 00000000 00000000 00000000 4a1e7d80 ffff8083 0049501c ffff8000
7cc0: 00005402 00000000 00aaa210 ffff8000 4a1e7ea0 ffff8083 000833f4 ffff8000
7ce0: ffffff9c ffffffff 92c23ba0 0000ffff 4a1e7ea0 ffff8083 001bfcc0 ffff8000
7d00: 4a0fc400 ffff8083 00005402 00000000 4a1e7d40 ffff8083 00490324 ffff8000
7d20: ffffff9c 00000000 92c23ba0 0000ffff 000a0000 00000000 00000000 00000000
7d40: 00000008 00000000 00080000 00000000 92c23b8b 0000ffff 92c23b8e 0000ffff
7d60: 00000038 00000000 00001cb2 00000000 00000005 00000000 92d7b498 0000ffff
7d80: 01010101 01010101 92be9000 0000ffff 00000000 00000000 00000030 00000000
[<ffff8000000833f4>] el1_dbg+0x18/0x6c
This issue is similar with 62c6c61("arm64: replace read_lock to rcu lock in
call_break_hook"), but comes to single_step_handler.
This also solves kgdbts boot test silent hang issue on 4.4 -rt kernel.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/arm64/kernel/debug-monitors.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 636ba8b6240b..89e72b3696fa 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -189,20 +189,21 @@ static void clear_regs_spsr_ss(struct pt_regs *regs)
/* EL1 Single Step Handler hooks */
static LIST_HEAD(step_hook);
-DEFINE_RWLOCK(step_hook_lock);
+static DEFINE_SPINLOCK(step_hook_lock);
void register_step_hook(struct step_hook *hook)
{
- write_lock(&step_hook_lock);
- list_add(&hook->node, &step_hook);
- write_unlock(&step_hook_lock);
+ spin_lock(&step_hook_lock);
+ list_add_rcu(&hook->node, &step_hook);
+ spin_unlock(&step_hook_lock);
}
void unregister_step_hook(struct step_hook *hook)
{
- write_lock(&step_hook_lock);
- list_del(&hook->node);
- write_unlock(&step_hook_lock);
+ spin_lock(&step_hook_lock);
+ list_del_rcu(&hook->node);
+ spin_unlock(&step_hook_lock);
+ synchronize_rcu();
}
/*
@@ -216,15 +217,15 @@ static int call_step_hook(struct pt_regs *regs, unsigned int esr)
struct step_hook *hook;
int retval = DBG_HOOK_ERROR;
- read_lock(&step_hook_lock);
+ rcu_read_lock();
- list_for_each_entry(hook, &step_hook, node) {
+ list_for_each_entry_rcu(hook, &step_hook, node) {
retval = hook->fn(regs, esr);
if (retval == DBG_HOOK_HANDLED)
break;
}
- read_unlock(&step_hook_lock);
+ rcu_read_unlock();
return retval;
}
--
2.7.0
next prev parent reply other threads:[~2016-03-03 14:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 15:44 [PATCH RT 00/17] Linux 3.14.61-rt64-rc1 Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 01/17] ptrace: dont open IRQs in ptrace_freeze_traced() too early Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 02/17] net: move xmit_recursion to per-task variable on -RT Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 03/17] preempt-lazy: Add the lazy-preemption check to preempt_schedule() Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 04/17] softirq: split timer softirqs out of ksoftirqd Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 05/17] net: provide a way to delegate processing a softirq to ksoftirqd Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 06/17] latencyhist: disable jump-labels Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 07/17] arm64: replace read_lock to rcu lock in call_step_hook Steven Rostedt
2016-03-03 4:23 ` Pratyush Anand
2016-03-03 14:12 ` Steven Rostedt
2016-03-03 14:21 ` Steven Rostedt [this message]
2016-03-02 15:44 ` [PATCH RT 08/17] kernel: migrate_disable() do fastpath in atomic & irqs-off Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 09/17] kernel: softirq: unlock with irqs on Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 10/17] kernel/stop_machine: partly revert "stop_machine: Use raw spinlocks" Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 11/17] sched,rt: __always_inline preemptible_lazy() Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 12/17] drm,radeon,i915: Use preempt_disable/enable_rt() where recommended Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 13/17] trace: Use rcuidle version for preemptoff_hist trace point Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 14/17] f2fs: Mutex cant be used by down_write_nest_lock() Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 15/17] rcu/torture: Comment out rcu_bh ops on PREEMPT_RT_FULL Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 16/17] kernel: sched: Fix preempt_disable_ip recodring for preempt_disable() Steven Rostedt
2016-03-02 15:44 ` [PATCH RT 17/17] Linux 3.14.61-rt64-rc1 Steven Rostedt
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