linux-kernel - [PATCH] ARM: SAMSUNG: use spin_lock_irqsave() in clk_set

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Message-Id: <1345058187-18843-1-git-send-email-msb@chromium.org>
Date:	Wed, 15 Aug 2012 12:16:27 -0700
From:	Mandeep Singh Baines <msb@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Mandeep Singh Baines <msb@...omium.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, Ben Dooks <ben-linux@...ff.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	Minho Ban <mhban@...sung.com>,
	Jaecheol Lee <jc.lee@...sung.com>,
	Sunyoung Kang <sy0816.kang@...sung.com>,
	Olof Johansson <olofj@...omium.org>
Subject: [PATCH] ARM: SAMSUNG: use spin_lock_irqsave() in clk_set_parent

>From 0cdf3aff, "ARM: SAMSUNG: use spin_lock_irqsave() in
clk_{enable,disable}":

  The clk_enable()and clk_disable() can be used process and ISR either.
  And actually it is used for real product and other platforms use it
  now. So spin_lock_irqsave() should be used instead.

We need to make a similar change in clk_set_parent(). Otherwise,
you can potentially get spinlock recursion:

BUG: spinlock recursion on CPU#0, kinteractive/68
 lock: 807832a8, .magic: dead4ead, .owner: kinteractive/68, .owner_cpu: 0
[<80015f54>] (unwind_backtrace+0x0/0x128) from [<804f2914>] (dump_stack+0x20/0x24)
[<804f2914>] (dump_stack+0x20/0x24) from [<804f57b8>] (spin_dump+0x80/0x94)
[<804f57b8>] (spin_dump+0x80/0x94) from [<804f57f8>] (spin_bug+0x2c/0x30)
[<804f57f8>] (spin_bug+0x2c/0x30) from [<80222730>] (do_raw_spin_lock+0x54/0x150)
[<80222730>] (do_raw_spin_lock+0x54/0x150) from [<804f96ec>] (_raw_spin_lock_irqsave+0x20/0x28)
[<804f96ec>] (_raw_spin_lock_irqsave+0x20/0x28) from [<80022ea4>] (clk_enable+0x3c/0x84)
[<80022ea4>] (clk_enable+0x3c/0x84) from [<8038336c>] (s5p_mfc_clock_on+0x60/0x74)
[<8038336c>] (s5p_mfc_clock_on+0x60/0x74) from [<8038645c>] (s5p_mfc_read_info+0x20/0x38)
[<8038645c>] (s5p_mfc_read_info+0x20/0x38) from [<8037ca3c>] (s5p_mfc_handle_frame+0x2e4/0x4bc)
[<8037ca3c>] (s5p_mfc_handle_frame+0x2e4/0x4bc) from [<8037d420>] (s5p_mfc_irq+0x1ec/0x6cc)
[<8037d420>] (s5p_mfc_irq+0x1ec/0x6cc) from [<8007fc74>] (handle_irq_event_percpu+0x8c/0x244)
[<8007fc74>] (handle_irq_event_percpu+0x8c/0x244) from [<8007fe78>] (handle_irq_event+0x4c/0x6c)
[<8007fe78>] (handle_irq_event+0x4c/0x6c) from [<80082dd8>] (handle_fasteoi_irq+0xe4/0x150)
[<80082dd8>] (handle_fasteoi_irq+0xe4/0x150) from [<8007f424>] (generic_handle_irq+0x3c/0x50)
[<8007f424>] (generic_handle_irq+0x3c/0x50) from [<8000f7c4>] (handle_IRQ+0x88/0xc8)
[<8000f7c4>] (handle_IRQ+0x88/0xc8) from [<80008564>] (gic_handle_irq+0x44/0x68)
[<80008564>] (gic_handle_irq+0x44/0x68) from [<8000e400>] (__irq_svc+0x40/0x60)
Exception stack(0xef3cbe68 to 0xef3cbeb0)
[<8000e400>] (__irq_svc+0x40/0x60) from [<80022cfc>] (clk_set_parent+0x30/0x74)
[<80022cfc>] (clk_set_parent+0x30/0x74) from [<803ac7f8>] (set_apll.isra.0+0x28/0xb0)
[<803ac7f8>] (set_apll.isra.0+0x28/0xb0) from [<803ac8e4>] (exynos5250_set_frequency+0x64/0xb8)
[<803ac8e4>] (exynos5250_set_frequency+0x64/0xb8) from [<803ac280>] (exynos_target+0x1b0/0x220)
[<803ac280>] (exynos_target+0x1b0/0x220) from [<803a4a0c>] (__cpufreq_driver_target+0xb0/0xd4)
[<803a4a0c>] (__cpufreq_driver_target+0xb0/0xd4) from [<803aab80>] (cpufreq_interactive_updown_task+0x214/0x264)
[<803aab80>] (cpufreq_interactive_updown_task+0x214/0x264) from [<80047d04>] (kthread+0x9c/0xa8)
[<80047d04>] (kthread+0x9c/0xa8) from [<8000fa48>] (kernel_thread_exit+0x0/0x8)

Signed-off-by: Mandeep Singh Baines <msb@...omium.org>
Suggested-by: Sunil Mazhavanchery <sunilm@...sung.com>
CC: linux-arm-kernel@...ts.infradead.org
CC: linux-samsung-soc@...r.kernel.org
CC: Ben Dooks <ben-linux@...ff.org>
CC: Kukjin Kim <kgene.kim@...sung.com>
CC: Russell King <linux@....linux.org.uk>
CC: Minho Ban <mhban@...sung.com>
CC: Jaecheol Lee <jc.lee@...sung.com>
CC: Sunyoung Kang <sy0816.kang@...sung.com>
CC: Kukjin Kim <kgene.kim@...sung.com>
CC: Olof Johansson <olofj@...omium.org>
---
 arch/arm/plat-samsung/clock.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c
index 65c5eca..80eacca 100644
--- a/arch/arm/plat-samsung/clock.c
+++ b/arch/arm/plat-samsung/clock.c
@@ -173,17 +173,18 @@ struct clk *clk_get_parent(struct clk *clk)
 
 int clk_set_parent(struct clk *clk, struct clk *parent)
 {
+	unsigned long flags;
 	int ret = 0;
 
 	if (IS_ERR(clk))
 		return -EINVAL;
 
-	spin_lock(&clocks_lock);
+	spin_lock_irqsave(&clocks_lock, flags);
 
 	if (clk->ops && clk->ops->set_parent)
 		ret = (clk->ops->set_parent)(clk, parent);
 
-	spin_unlock(&clocks_lock);
+	spin_unlock_irqrestore(&clocks_lock, flags);
 
 	return ret;
 }
-- 
1.7.7.3

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