Rework r348303 to reduce the time of holding global BPF lock.
It appeared that using NET_EPOCH_WAIT() while holding global BPF lock can lead to another panic: spin lock 0xfffff800183c9840 (turnstile lock) held by 0xfffff80018e2c5a0 (tid 100325) too long panic: spin lock held too long ... #0 sched_switch (td=0xfffff80018e2c5a0, newtd=0xfffff8000389e000, flags=<optimized out>) at /usr/src/sys/kern/sched_ule.c:2133 #1 0xffffffff80bf9912 in mi_switch (flags=256, newtd=0x0) at /usr/src/sys/kern/kern_synch.c:439 #2 0xffffffff80c21db7 in sched_bind (td=<optimized out>, cpu=<optimized out>) at /usr/src/sys/kern/sched_ule.c:2704 #3 0xffffffff80c34c33 in epoch_block_handler_preempt (global=<optimized out>, cr=0xfffffe00005a1a00, arg=<optimized out>) at /usr/src/sys/kern/subr_epoch.c:394 #4 0xffffffff803c741b in epoch_block (global=<optimized out>, cr=<optimized out>, cb=<optimized out>, ct=<optimized out>) at /usr/src/sys/contrib/ck/src/ck_epoch.c:416 #5 ck_epoch_synchronize_wait (global=0xfffff8000380cd80, cb=<optimized out>, ct=<optimized out>) at /usr/src/sys/contrib/ck/src/ck_epoch.c:465 #6 0xffffffff80c3475e in epoch_wait_preempt (epoch=0xfffff8000380cd80) at /usr/src/sys/kern/subr_epoch.c:513 #7 0xffffffff80ce970b in bpf_detachd_locked (d=0xfffff801d309cc00, detached_ifp=<optimized out>) at /usr/src/sys/net/bpf.c:856 #8 0xffffffff80ced166 in bpf_detachd (d=<optimized out>) at /usr/src/sys/net/bpf.c:836 #9 bpf_dtor (data=0xfffff801d309cc00) at /usr/src/sys/net/bpf.c:914 To fix this add the check to the catchpacket() that BPF descriptor was not detached just before we acquired BPFD_LOCK(). Reported by: slavash Tested by: slavash MFC after: 1 week
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=348324
@ -850,15 +850,10 @@ bpf_detachd_locked(struct bpf_d *d, bool detached_ifp)
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/* Check if descriptor is attached */
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if ((bp = d->bd_bif) == NULL)
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return;
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/*
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* Remove d from the interface's descriptor list.
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* And wait until bpf_[m]tap*() will finish their possible work
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* with descriptor.
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*/
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CK_LIST_REMOVE(d, bd_next);
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NET_EPOCH_WAIT();
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BPFD_LOCK(d);
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/* Remove d from the interface's descriptor list. */
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CK_LIST_REMOVE(d, bd_next);
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/* Save bd_writer value */
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error = d->bd_writer;
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ifp = bp->bif_ifp;
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@ -2494,6 +2489,11 @@ catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
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int tstype;
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BPFD_LOCK_ASSERT(d);
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if (d->bd_bif == NULL) {
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/* Descriptor was detached in concurrent thread */
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counter_u64_add(d->bd_dcount, 1);
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return;
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}
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/*
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* Detect whether user space has released a buffer back to us, and if
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