Andrew Thompson wrote:
On Fri, May 08, 2009 at 01:41:04PM -0400, John Baldwin wrote:
Andrew Thompson wrote:
Author: thompsa
Date: Fri May 8 13:44:33 2009
New Revision: 191912
URL: http://svn.freebsd.org/changeset/base/191912
Log:
Drain the tasks before the interface stop call in case a restart was queued.
Actually, you have to drain it after if_detach() so you can safely destroy
the lock. The proper order should be something like this:
bpfdetach(ifp);
ieee80211_ifdetach(ic);
ipw_stop(sc);
callout_drain();
ieee80211_draintask();
ipw_release(sc);
This is the order other NIC drivers use where they do something like:
ether_ifdetach(ifp);
FOO_LOCK(sc);
foo_stop(sc); // calls callout_stop()
FOO_UNLOCK(sc);
callout_drain();
taskqueue_drain(); // only if it uses tasks
if_free();
mtx_destroy();
ieee80211_ifdetach() will actually free the taskqueue, it doesnt use one
of the persistent system ones. It wasnt incorrect before as the
interface would still be brought down before net80211 detached, it was
just to reduce the flip flopping. With that noted does it still need
reordering?
Assuming that free'ing a taskqueue drains any tasks, then you don't
actually need to drain the task queue in that case. However, you should
still move the foo_stop() after if_detach() as userland ioctl requests
are still able to call your driver's ioctl() routine until if_detach()
returns. So perhaps something like this:
bpfdetach()
ieee80211_ifdetach()
ipw_stop();
callout_drain();
ipw_release();
In general, it isn't really safe to shutdown the hardware (foo_stop())
until you have detached the driver from external code paths (ifnet, bpf,
etc.).
--
John Baldwin
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