Date: Sat, 18 Mar 2000 21:42:34 -0800 (PST) From: Robert Watson <rwatson@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/net bpf.c bpf.h Message-ID: <200003190542.VAA29960@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
rwatson 2000/03/18 21:42:34 PST
Modified files:
sys/net bpf.c bpf.h
Log:
The advent of if_detach, allowing interface removal at runtime, makes it
possible for a panic to occur if BPF is in use on the interface at the
time of the call to if_detach. This happens because BPF maintains pointers
to the struct ifnet describing the interface, which is freed by if_detach.
To correct this problem, a new call, bpfdetach, is introduced. bpfdetach
locates BPF descriptor references to the interface, and NULLs them. Other
BPF code is modified so that discovery of a NULL interface results in
ENXIO (already implemented for some calls). Processes blocked on a BPF
call will also be woken up so that they can receive ENXIO.
Interface drivers that invoke bpfattach and if_detach must be modified to
also call bpfattach(ifp) before calling if_detach(ifp). This is relevant
for buses that support hot removal, such as pccard and usb. Patches to
all effected devices will not be committed, only to if_wi.c, due to
testing limitations. To reproduce the crash, load up tcpdump on you
favorite pccard ethernet card, and then eject the card. As some pccard
drivers do not invoke if_detach(ifp), this bug will not manifest itself
for those drivers.
Reviewed by: wes
Revision Changes Path
1.61 +64 -1 src/sys/net/bpf.c
1.23 +3 -1 src/sys/net/bpf.h
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200003190542.VAA29960>