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authorMarek Vasut <marex@denx.de>2014-03-24 06:38:10 +0400
committerLinus Walleij <linus.walleij@linaro.org>2014-03-27 13:11:59 +0400
commita585f87c863e4e1d496459d382b802bf5ebe3717 (patch)
tree4e46aadc0a7d2159e010579406b43a9ce71eb8ca /drivers/gpio
parent24016ab6a857fef060b29a9714649dcb80dc77c1 (diff)
downloadlinux-a585f87c863e4e1d496459d382b802bf5ebe3717.tar.xz
gpio: mxs: Allow for recursive enable_irq_wake() call
The scenario here is that someone calls enable_irq_wake() from somewhere in the code. This will result in the lockdep producing a backtrace as can be seen below. In my case, this problem is triggered when using the wl1271 (TI WlCore) driver found in drivers/net/wireless/ti/ . The problem cause is rather obvious from the backtrace, but let's outline the dependency. enable_irq_wake() grabs the IRQ buslock in irq_set_irq_wake(), which in turns calls mxs_gpio_set_wake_irq() . But mxs_gpio_set_wake_irq() calls enable_irq_wake() again on the one-level-higher IRQ , thus it tries to grab the IRQ buslock again in irq_set_irq_wake() . Because the spinlock in irq_set_irq_wake()->irq_get_desc_buslock()->__irq_get_desc_lock() is not marked as recursive, lockdep will spew the stuff below. We know we can safely re-enter the lock, so use IRQ_GC_INIT_NESTED_LOCK to fix the spew. ============================================= [ INFO: possible recursive locking detected ] 3.10.33-00012-gf06b763-dirty #61 Not tainted --------------------------------------------- kworker/0:1/18 is trying to acquire lock: (&irq_desc_lock_class){-.-...}, at: [<c00685f0>] __irq_get_desc_lock+0x48/0x88 but task is already holding lock: (&irq_desc_lock_class){-.-...}, at: [<c00685f0>] __irq_get_desc_lock+0x48/0x88 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&irq_desc_lock_class); lock(&irq_desc_lock_class); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/0:1/18: #0: (events){.+.+.+}, at: [<c0036308>] process_one_work+0x134/0x4a4 #1: ((&fw_work->work)){+.+.+.}, at: [<c0036308>] process_one_work+0x134/0x4a4 #2: (&irq_desc_lock_class){-.-...}, at: [<c00685f0>] __irq_get_desc_lock+0x48/0x88 stack backtrace: CPU: 0 PID: 18 Comm: kworker/0:1 Not tainted 3.10.33-00012-gf06b763-dirty #61 Workqueue: events request_firmware_work_func [<c0013eb4>] (unwind_backtrace+0x0/0xf0) from [<c0011c74>] (show_stack+0x10/0x14) [<c0011c74>] (show_stack+0x10/0x14) from [<c005bb08>] (__lock_acquire+0x140c/0x1a64) [<c005bb08>] (__lock_acquire+0x140c/0x1a64) from [<c005c6a8>] (lock_acquire+0x9c/0x104) [<c005c6a8>] (lock_acquire+0x9c/0x104) from [<c051d5a4>] (_raw_spin_lock_irqsave+0x44/0x58) [<c051d5a4>] (_raw_spin_lock_irqsave+0x44/0x58) from [<c00685f0>] (__irq_get_desc_lock+0x48/0x88) [<c00685f0>] (__irq_get_desc_lock+0x48/0x88) from [<c0068e78>] (irq_set_irq_wake+0x20/0xf4) [<c0068e78>] (irq_set_irq_wake+0x20/0xf4) from [<c027260c>] (mxs_gpio_set_wake_irq+0x1c/0x24) [<c027260c>] (mxs_gpio_set_wake_irq+0x1c/0x24) from [<c0068cf4>] (set_irq_wake_real+0x30/0x44) [<c0068cf4>] (set_irq_wake_real+0x30/0x44) from [<c0068ee4>] (irq_set_irq_wake+0x8c/0xf4) [<c0068ee4>] (irq_set_irq_wake+0x8c/0xf4) from [<c0310748>] (wlcore_nvs_cb+0x10c/0x97c) [<c0310748>] (wlcore_nvs_cb+0x10c/0x97c) from [<c02be5e8>] (request_firmware_work_func+0x38/0x58) [<c02be5e8>] (request_firmware_work_func+0x38/0x58) from [<c0036394>] (process_one_work+0x1c0/0x4a4) [<c0036394>] (process_one_work+0x1c0/0x4a4) from [<c0036a4c>] (worker_thread+0x138/0x394) [<c0036a4c>] (worker_thread+0x138/0x394) from [<c003cb74>] (kthread+0xa4/0xb0) [<c003cb74>] (kthread+0xa4/0xb0) from [<c000ee00>] (ret_from_fork+0x14/0x34) wlcore: loaded Cc: stable@vger.kernel.org Signed-off-by: Marek Vasut <marex@denx.de> Acked-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpio-mxs.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpio/gpio-mxs.c b/drivers/gpio/gpio-mxs.c
index 532bcb336eff..8ffdd7d2bade 100644
--- a/drivers/gpio/gpio-mxs.c
+++ b/drivers/gpio/gpio-mxs.c
@@ -214,7 +214,8 @@ static void __init mxs_gpio_init_gc(struct mxs_gpio_port *port, int irq_base)
ct->regs.ack = PINCTRL_IRQSTAT(port) + MXS_CLR;
ct->regs.mask = PINCTRL_IRQEN(port);
- irq_setup_generic_chip(gc, IRQ_MSK(32), 0, IRQ_NOREQUEST, 0);
+ irq_setup_generic_chip(gc, IRQ_MSK(32), IRQ_GC_INIT_NESTED_LOCK,
+ IRQ_NOREQUEST, 0);
}
static int mxs_gpio_to_irq(struct gpio_chip *gc, unsigned offset)