linux-kernel - Re: [BUG] gpio: gpio-adp5588: A possible sleep-in-atomic-context bug in adp5588_gpio_direction

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Message-ID: <09f55bb2-f178-af95-8843-ff5fd25a4eed@analog.com>
Date:   Mon, 13 Aug 2018 13:08:16 +0200
From:   Michael Hennerich <michael.hennerich@...log.com>
To:     Jia-Ju Bai <baijiaju1990@...il.com>, <linus.walleij@...aro.org>
CC:     <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] gpio: gpio-adp5588: A possible sleep-in-atomic-context bug
 in adp5588_gpio_direction_input()

On 11.08.2018 04:03, Jia-Ju Bai wrote:
> The driver may sleep with holding a spinlock.
> 
> The function call paths (from bottom to top) in Linux-4.16 are:
> 
> [FUNC] mutex_lock_nested
> drivers/gpio/gpio-adp5588.c, 113: mutex_lock_nested in 
> adp5588_gpio_direction_input
> drivers/gpio/gpio-adp5588.c, 224: adp5588_gpio_direction_input in 
> adp5588_irq_set_type
> kernel/irq/manage.c, 686: [FUNC_PTR]adp5588_irq_set_type in 
> __irq_set_trigger
> kernel/irq/manage.c, 1350: __irq_set_trigger in __setup_irq
> kernel/irq/manage.c, 1238: _raw_spin_lock_irqsave in __setup_irq
> 
> Note that [FUNC_PTR] means a function pointer call is used.
> 
> I do not find a good way to fix, so I only report.
> This is found by my static analysis tool (DSAC).
> 

Confirmed - adp5588_irq_set_type calls are atomic context and hence must 
not sleep. I'll move this stuff to irq_bus_sync_unlock.

Patch will be provided.

-- 
Greetings,
Michael

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