Fix panic introduced by r235745. Panic occurs after first packet traverse renamed interface.
Add several comments on locking Found by: avg Approved by: ae(mentor) Tested by: avg MFC after: 1 week
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=236559
@ -1704,6 +1704,14 @@ bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
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/*
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* Set d's packet filter program to fp. If this file already has a filter,
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* free it and replace it. Returns EINVAL for bogus requests.
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*
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* Note we need global lock here to serialize bpf_setf() and bpf_setif() calls
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* since reading d->bd_bif can't be protected by d or interface lock due to
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* lock order.
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*
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* Additionally, we have to acquire interface write lock due to bpf_mtap() uses
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* interface read lock to read all filers.
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*
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*/
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static int
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bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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@ -2535,20 +2543,32 @@ bpfdetach(struct ifnet *ifp)
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}
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/*
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* Interface departure handler
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* Interface departure handler.
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* Note departure event does not guagantee interface is going down.
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*/
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static void
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bpf_ifdetach(void *arg __unused, struct ifnet *ifp)
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{
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struct bpf_if *bp;
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if ((bp = ifp->if_bpf) == NULL)
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BPF_LOCK();
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if ((bp = ifp->if_bpf) == NULL) {
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BPF_UNLOCK();
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return;
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}
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/* Check if bpfdetach() was called previously */
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if ((bp->flags & BPFIF_FLAG_DYING) == 0) {
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BPF_UNLOCK();
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return;
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}
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CTR3(KTR_NET, "%s: freing BPF instance %p for interface %p",
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__func__, bp, ifp);
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ifp->if_bpf = NULL;
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BPF_UNLOCK();
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rw_destroy(&bp->bif_lock);
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free(bp, M_BPF);
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}
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