linux-kernel - Re: [PATCH 1/2] gpio: omap: move pm runtime in irq_chip.irq_bus_lock/sync

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Date:	Fri, 2 Oct 2015 05:22:15 -0700
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Grygorii Strashko <grygorii.strashko@...com>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Tony Lindgren <tony@...mide.com>,
	Linux-OMAP <linux-omap@...r.kernel.org>,
	Austin Schuh <austin@...oton-tech.com>,
	philipp@...oton-tech.com, linux-rt-users@...r.kernel.org,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] gpio: omap: move pm runtime in irq_chip.irq_bus_lock/sync_unlock

On Fri, Sep 25, 2015 at 12:28 PM, Grygorii Strashko
<grygorii.strashko@...com> wrote:

> The PM runtime API can't be used in atomic contex on -RT even if
> it's configured as irqsafe. As result, below error report can
> be seen when PM runtime API called from IRQ chip's callbacks
> irq_startup/irq_shutdown/irq_set_type, because they are
> protected by RAW spinlock:
>
> BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
> in_atomic(): 1, irqs_disabled(): 128, pid: 96, name: insmod
> 3 locks held by insmod/96:
>  #0:  (&dev->mutex){......}, at: [<c04752c8>] __driver_attach+0x54/0xa0
>  #1:  (&dev->mutex){......}, at: [<c04752d4>] __driver_attach+0x60/0xa0
>  #2:  (class){......}, at: [<c00a408c>] __irq_get_desc_lock+0x60/0xa4
> irq event stamp: 1834
> hardirqs last  enabled at (1833): [<c06ab2a4>] _raw_spin_unlock_irqrestore+0x88/0x90
> hardirqs last disabled at (1834): [<c06ab068>] _raw_spin_lock_irqsave+0x2c/0x64
> softirqs last  enabled at (0): [<c003d220>] copy_process.part.52+0x410/0x19d8
> softirqs last disabled at (0): [<  (null)>]   (null)
> Preemption disabled at:[<  (null)>]   (null)
>
> CPU: 1 PID: 96 Comm: insmod Tainted: G        W  O    4.1.3-rt3-00618-g57e2387-dirty #184
> Hardware name: Generic DRA74X (Flattened Device Tree)
> [<c00190f4>] (unwind_backtrace) from [<c0014734>] (show_stack+0x20/0x24)
> [<c0014734>] (show_stack) from [<c06a62ec>] (dump_stack+0x88/0xdc)
> [<c06a62ec>] (dump_stack) from [<c006ca44>] (___might_sleep+0x198/0x2a8)
> [<c006ca44>] (___might_sleep) from [<c06ab6d4>] (rt_spin_lock+0x30/0x70)
> [<c06ab6d4>] (rt_spin_lock) from [<c04815ac>] (__pm_runtime_resume+0x68/0xa4)
> [<c04815ac>] (__pm_runtime_resume) from [<c04123f4>] (omap_gpio_irq_type+0x188/0x1d8)
> [<c04123f4>] (omap_gpio_irq_type) from [<c00a64e4>] (__irq_set_trigger+0x68/0x130)
> [<c00a64e4>] (__irq_set_trigger) from [<c00a7bc4>] (irq_set_irq_type+0x44/0x6c)
> [<c00a7bc4>] (irq_set_irq_type) from [<c00abbf8>] (irq_create_of_mapping+0x120/0x174)
> [<c00abbf8>] (irq_create_of_mapping) from [<c0577b74>] (of_irq_get+0x48/0x58)
> [<c0577b74>] (of_irq_get) from [<c0540a14>] (i2c_device_probe+0x54/0x15c)
> [<c0540a14>] (i2c_device_probe) from [<c04750dc>] (driver_probe_device+0x184/0x2c8)
> [<c04750dc>] (driver_probe_device) from [<c0475310>] (__driver_attach+0x9c/0xa0)
> [<c0475310>] (__driver_attach) from [<c0473238>] (bus_for_each_dev+0x7c/0xb0)
> [<c0473238>] (bus_for_each_dev) from [<c0474af4>] (driver_attach+0x28/0x30)
> [<c0474af4>] (driver_attach) from [<c0474760>] (bus_add_driver+0x154/0x200)
> [<c0474760>] (bus_add_driver) from [<c0476348>] (driver_register+0x88/0x108)
> [<c0476348>] (driver_register) from [<c0541600>] (i2c_register_driver+0x3c/0x90)
> [<c0541600>] (i2c_register_driver) from [<bf003018>] (pcf857x_init+0x18/0x24 [gpio_pcf857x])
> [<bf003018>] (pcf857x_init [gpio_pcf857x]) from [<c000998c>] (do_one_initcall+0x128/0x1e8)
> [<c000998c>] (do_one_initcall) from [<c06a4220>] (do_init_module+0x6c/0x1bc)
> [<c06a4220>] (do_init_module) from [<c00dd0c8>] (load_module+0x18e8/0x21c4)
> [<c00dd0c8>] (load_module) from [<c00ddaa0>] (SyS_init_module+0xfc/0x158)
> [<c00ddaa0>] (SyS_init_module) from [<c000ff40>] (ret_fast_syscall+0x0/0x54)
>
> The IRQ chip interface defines only two callbacks which are executed in
> non-atomic contex - irq_bus_lock/irq_bus_sync_unlock, so lets move
> PM runtime calls there.
>
> Tested-by: Tony Lindgren <tony@...mide.com>
> Tested-by: Austin Schuh <austin@...oton-tech.com>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>

Patch applied with Santosh's ACK.

Yours,
Linus Walleij
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