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write down some observations about the locking wild west around if_mcast_op()

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jdolecek 2020-05-05 09:33:39 +00:00
parent ede9f9f8d5
commit 02cc0c4d4e
1 changed files with 12 additions and 1 deletions
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13
doc/TODO.smpnet
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@ -1,4 +1,4 @@
$NetBSD: TODO.smpnet,v 1.34 2020/01/20 18:40:06 thorpej Exp $
$NetBSD: TODO.smpnet,v 1.35 2020/05/05 09:33:39 jdolecek Exp $
MP-safe components
==================
@ -121,6 +121,17 @@ provide a deferred bpf_mtap mechanism that forcibly runs bpf_mtap in softint
context. It's a workaround and once the functions run in softint, we should use
the original bpf_mtap again.
if_mcast_op() - SIOCADDMULTI/SIOCDELMULTI
-----------------------------------------
Helper function is called to add or remove multicast addresses for
interface. When called via ioctl it takes IFNET_LOCK(), when called
via sosetopt() it doesn't.
Various network drivers can't assert IFNET_LOCKED() in their if_ioctl
because of this. Generally drivers still take care to splnet() even
with NET_MPSAFE before calling ether_ioctl(), but they do not take
KERNEL_LOCK(), so this is actually unsafe.
Lingering obsolete variables
-----------------------------