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| /openbmc/linux/net/xfrm/ |
| H A D | xfrm_state.c | a47f0ce0 Thu Aug 24 05:54:22 CDT 2006 David S. Miller <davem@sunset.davemloft.net> [XFRM]: Kill excessive refcounting of xfrm_state objects.
The refcounting done for timers and hash table insertions
are just wasted cycles. We can eliminate all of this
refcounting because:
1) The implicit refcount when the xfrm_state object is active
will always be held while the object is in the hash tables.
We never kfree() the xfrm_state until long after we've made
sure that it has been unhashed.
2) Timers are even easier. Once we mark that x->km.state as
anything other than XFRM_STATE_VALID (__xfrm_state_delete
sets it to XFRM_STATE_DEAD), any timer that fires will
do nothing and return without rearming the timer.
Therefore we can defer the del_timer calls until when the
object is about to be freed up during GC. We have to use
del_timer_sync() and defer it to GC because we can't do
a del_timer_sync() while holding x->lock which all callers
of __xfrm_state_delete hold.
This makes SA changes even more light-weight.
Signed-off-by: David S. Miller <davem@davemloft.net>
a47f0ce0 Thu Aug 24 05:54:22 CDT 2006 David S. Miller <davem@sunset.davemloft.net> [XFRM]: Kill excessive refcounting of xfrm_state objects.
The refcounting done for timers and hash table insertions
are just wasted cycles. We can eliminate all of this
refcounting because:
1) The implicit refcount when the xfrm_state object is active
will always be held while the object is in the hash tables.
We never kfree() the xfrm_state until long after we've made
sure that it has been unhashed.
2) Timers are even easier. Once we mark that x->km.state as
anything other than XFRM_STATE_VALID (__xfrm_state_delete
sets it to XFRM_STATE_DEAD), any timer that fires will
do nothing and return without rearming the timer.
Therefore we can defer the del_timer calls until when the
object is about to be freed up during GC. We have to use
del_timer_sync() and defer it to GC because we can't do
a del_timer_sync() while holding x->lock which all callers
of __xfrm_state_delete hold.
This makes SA changes even more light-weight.
Signed-off-by: David S. Miller <davem@davemloft.net>
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