cvs commit: src/sys/dev/ed if_ed.c if_ed_pccard.c if_edvar.h
ru at freebsd.org
Sun Sep 18 22:40:40 PDT 2005
On Sun, Sep 18, 2005 at 08:51:34PM +0000, Warner Losh wrote:
> o Fix one bug that's common to many drivers. call if_free(ifp) after
> we tear down the interrupt. ed_intr() depends on ifp being there and
> freeing it while interrupts can still happen is, ummm, bad.
I think this change is a mismerge from some of your work with my work
already in CVS. if_free(ifp) is already called in ed_release_resources(),
which is used both in the failure case in ed_*_attach() and in ed_detach().
What's now in CVS should cause freeing a NULL pointer on detach.
About the commonality... Usually foo_stop() (which is called first in
foo_detach() if you were talking about the detach) disables interrupts,
so foo_intr() doesn't usually happen. From reading the code, I see the
same holds true for ed(4).
OTOH, it was shown that on some SMP machines it's possible to get a
call to foo_intr() after foo_stop() has been called by foo_shutdown(),
which will lead to a panic in most of the drivers. See kern/85005 and
kern/62889 for some examples.
I think the generic solution to this problem should be to return from
foo_intr() quickly if IFF_DRV_RUNNING is not set.
ru at FreeBSD.org
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