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Commit eb831743 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
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char: nwbutton: open-code interruptible_sleep_on 



The nwbutton driver uses interruptible_sleep_on to wait for buttons
getting pressed after we enter the read() function, which is inherently
racy and cannot be fixed by using wait_event without changing the
driver's user space interface.

Instead, this patch just uses an open-coded variant of the same
interruptible_sleep_on() call, so the driver behavior doesn't change
but we remove the sleep_on family from the kernel.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 83ce0741

drivers/char/nwbutton.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -168,7 +168,10 @@ static irqreturn_t button_handler (int irq, void *dev_id) 
static int button_read (struct file *filp, char __user *buffer,

static int button_read (struct file *filp, char __user *buffer,

			size_t count, loff_t *ppos)

			size_t count, loff_t *ppos)

{

{

	interruptible_sleep_on (&button_wait_queue);

	DEFINE_WAIT(wait);

	prepare_to_wait(&button_wait_queue, &wait, TASK_INTERRUPTIBLE);

	schedule();

	finish_wait(&button_wait_queue, &wait);

	return (copy_to_user (buffer, &button_output_buffer, bcount))

	return (copy_to_user (buffer, &button_output_buffer, bcount))

		 ? -EFAULT : bcount;

		 ? -EFAULT : bcount;

}

}