Re: [PATCH] remove BKL from drivers' release functions

Russell King
2001-11-29T00:43:13Z

On Wed, Nov 28, 2001 at 04:26:16PM -0800, David C. Hansen wrote:
> I wrote a quick and dirty char device driver to see if this happened.
> If I run two tasks doing a bunch of opens and closes, the -EBUSY
> condition in the open function does happen. Is my driver doing
> something wrong?

What's happening is:

task 1 task 2
-> sys_open
-> lock_kernel
-> testdev_open
-> test_and_set_bit
return success
unlock kernel
-> sys_open
-> lock_kernel (blocks on it)
-> testdev_open
-> test_and_set_bit
return -EBUSY
unlock kernel
return
return

The BKL is only held for the duration of the open, not until you close the
device.

--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux