linux-kernel - [BUG] drivers/gpio: some possible sleep-in-atomic bugs

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Date:   Tue, 12 Dec 2017 11:59:26 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     linus.walleij@...aro.org, andreas@...sler.com
Cc:     linux-gpio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] drivers/gpio: some possible sleep-in-atomic bugs

According to drivers/gpio/gpio-grgpio.c, the kernel module may sleep 
under a spinlock.
The function call paths are:
grgpio_remove (acquire the spinlock)
   gpiochip_remove
     gpiochip_sysfs_unregister
       device_unregister --> may sleep
       mutex_lock --> may sleep

grgpio_remove (acquire the spinlock)
   gpiochip_remove
     gpiochip_sysfs_unregister
       gpiod_free
         __gpiod_free
           gpiod_unexport
             device_unregister --> may sleep
             mutex_lock --> may sleep

grgpio_remove (acquire the spinlock)
   irq_domain_remove
     mutex_lock --> may sleep

grgpio_irq_map (acquire the spinlock)
   request_irq --> may sleep

grgpio_irq_unmap (acquire the spinlock)
   free_irq --> may sleep


I do not find a good way to fix them, so I only report.
These possible bugs is found by my static analysis tool (DSAC) and 
checked by my code review.


Thanks,
Jia-Ju Bai