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Commit 1d7c4903 authored by Wilson Kok's avatar Wilson Kok Committed by David S. Miller
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bridge: use _bh spinlock variant for br_fdb_update to avoid lockup



br_fdb_update() can be called in process context in the following way:
br_fdb_add() -> __br_fdb_add() -> br_fdb_update() (if NTF_USE flag is set)
so we need to use spin_lock_bh because there are softirq users of the
hash_lock. One easy way to reproduce this is to modify the bridge utility
to set NTF_USE, enable stp and then set maxageing to a low value so
br_fdb_cleanup() is called frequently and then just add new entries in
a loop. This happens because br_fdb_cleanup() is called from timer/softirq
context. These locks were _bh before commit f8ae737d
("[BRIDGE]: forwarding remove unneeded preempt and bh diasables")
and at the time that commit was correct because br_fdb_update() couldn't be
called from process context, but that changed after commit:
292d1398 ("bridge: add NTF_USE support")

Signed-off-by: default avatarWilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: default avatarNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Fixes: 292d1398 ("bridge: add NTF_USE support")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 078b29d7
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