From dbc5e1e89aafd484ad279ec6b9267dcd2c67df3f Mon Sep 17 00:00:00 2001 From: Mandeep Singh Baines Date: Mon, 27 Aug 2012 09:42:37 -0700 Subject: [PATCH 1/2] 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 Suggested-by: Sunil Mazhavanchery Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: Ben Dooks Cc: Russell King Cc: Minho Ban Cc: Jaecheol Lee Cc: Sunyoung Kang Cc: Olof Johansson Signed-off-by: Kukjin Kim --- arch/arm/plat-samsung/clock.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c index 65c5eca475e7..80eacca4682a 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; } From d6838a62b4d36d3e2791cffe155586973b20a381 Mon Sep 17 00:00:00 2001 From: Tushar Behera Date: Tue, 18 Sep 2012 10:05:34 +0900 Subject: [PATCH 2/2] ARM: SAMSUNG: Use spin_lock_{irqsave,irqrestore} in clk_set_rate The spinlock clocks_lock can be held during ISR, hence it is not safe to hold that lock with disabling interrupts. It fixes following potential deadlock. ========================================================= [ INFO: possible irq lock inversion dependency detected ] 3.6.0-rc4+ #2 Not tainted --------------------------------------------------------- swapper/0/1 just changed the state of lock: (&(&host->lock)->rlock){-.....}, at: [] sdhci_irq+0x15/0x564 but this lock took another, HARDIRQ-unsafe lock in the past: (clocks_lock){+.+...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(clocks_lock); local_irq_disable(); lock(&(&host->lock)->rlock); lock(clocks_lock); lock(&(&host->lock)->rlock); *** DEADLOCK *** Signed-off-by: Tushar Behera Signed-off-by: Kukjin Kim --- arch/arm/plat-samsung/clock.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c index 80eacca4682a..d1116e2dfbea 100644 --- a/arch/arm/plat-samsung/clock.c +++ b/arch/arm/plat-samsung/clock.c @@ -144,6 +144,7 @@ long clk_round_rate(struct clk *clk, unsigned long rate) int clk_set_rate(struct clk *clk, unsigned long rate) { + unsigned long flags; int ret; if (IS_ERR(clk)) @@ -159,9 +160,9 @@ int clk_set_rate(struct clk *clk, unsigned long rate) if (clk->ops == NULL || clk->ops->set_rate == NULL) return -EINVAL; - spin_lock(&clocks_lock); + spin_lock_irqsave(&clocks_lock, flags); ret = (clk->ops->set_rate)(clk, rate); - spin_unlock(&clocks_lock); + spin_unlock_irqrestore(&clocks_lock, flags); return ret; }