SADB_X_SPDFLUSH message handling for latest version of IPsec

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Hi, all:

Recently I found the behavior for the command "setkey -FP" is quite 
different for the latest version IPsec (known as FAST_IPSEC before). 
Before the command would erase all the existed SP entries; currently the 
command would not. After digging the codes, I found the state of the SP 
entries will be set as IPSEC_SPSTATE_DEAD, but the entries will not be 
unlink from the SPD. Why needs to keep the entry in SPD? Is there any 
special purpose? Without the removal, it's hard to tell whether the SP 
entry still takes effect since "setkey -PD" will not show its status. On 
the other hand, SA is like usual, once the "setkey -F" is typed in, the 
SA entries will be erased right away.

Thanks.

BR,

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