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authorbrian <brian@FreeBSD.org>2001-06-20 10:06:28 +0000
committerbrian <brian@FreeBSD.org>2001-06-20 10:06:28 +0000
commitfcb8a3a2e689c0a1aa317b24fc10b7e3b42fa1d4 (patch)
tree7cd7432ed74414cdac2bf0900fdcbba3fccfbfeb /sys/net
parent9f7dbbc5e360447f2f66edcb39f1a20c6314e738 (diff)
downloadFreeBSD-src-fcb8a3a2e689c0a1aa317b24fc10b7e3b42fa1d4.zip
FreeBSD-src-fcb8a3a2e689c0a1aa317b24fc10b7e3b42fa1d4.tar.gz
Close a race where we were releasing the unit resource at the start
of tunclose() rather than the end, and tunopen() grabbed that unit before tunclose() finished (one process is allocating it while another is freeing it!). It may be worth hanging some sort of rw mutex around all specinfo calls where d_close and the detach handler get a write lock and all other functions get a read lock. This would guarantee certain levels of ``atomicity'' (is that a word?) that people may expect (I believe Solaris does something like this).
Diffstat (limited to 'sys/net')
-rw-r--r--sys/net/if_tun.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/sys/net/if_tun.c b/sys/net/if_tun.c
index 0194995..68cef88 100644
--- a/sys/net/if_tun.c
+++ b/sys/net/if_tun.c
@@ -307,8 +307,7 @@ tunclose(dev_t dev, int foo, int bar, struct proc *p)
tp = dev->si_drv1;
ifp = &tp->tun_if;
- err = rman_release_resource(tp->r_unit);
- KASSERT(err == 0, ("Unit %d not marked open", ifp->if_unit));
+ KASSERT(tp->r_unit, ("Unit %d not marked open", ifp->if_unit));
tp->tun_flags &= ~TUN_OPEN;
tp->tun_pid = 0;
@@ -340,6 +339,9 @@ tunclose(dev_t dev, int foo, int bar, struct proc *p)
selwakeup(&tp->tun_rsel);
TUNDEBUG ("%s%d: closed\n", ifp->if_name, ifp->if_unit);
+ err = rman_release_resource(tp->r_unit);
+ KASSERT(err == 0, ("Unit %d failed to release", ifp->if_unit));
+
return (0);
}
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