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authorArnd Bergmann <arnd@arndb.de>2014-01-02 13:07:53 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-08 15:29:52 -0800
commiteb831743f2b43253b0aec40f66a95fdcf8f178cc (patch)
treec1b2787fa11d6bfe36a9964d3db7782fbe789b16 /drivers/char
parent83ce07411dc2316aaaf95a0f193fa2fd76e2e739 (diff)
downloadlinux-linaro-stable-eb831743f2b43253b0aec40f66a95fdcf8f178cc.tar.gz
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: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/nwbutton.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/char/nwbutton.c b/drivers/char/nwbutton.c
index 1fd00dc06897..76c490fa0511 100644
--- a/drivers/char/nwbutton.c
+++ b/drivers/char/nwbutton.c
@@ -168,7 +168,10 @@ static irqreturn_t button_handler (int irq, void *dev_id)
static int button_read (struct file *filp, char __user *buffer,
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))
? -EFAULT : bcount;
}