Re: [PATCH v4 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients
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From: Stanislav Kinsbursky <hidden>
Date: 2011-09-20 14:35:51
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20.09.2011 18:14, Myklebust, Trond пишет:
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Doesn't it need to be protected by rpcb_clnt_lock too?Nope from my pow. It's protected by rpcb_create_local_mutex. I.e. no one will change rpcb_users since it's zero. If it's non zero - we willn't get to rpcb_set_local().OK, so you are saying that the rpcb_users++ below could be replaced by rpcb_users=1?
Yes, you right.
In that case, don't you need a smp_wmb() between the setting of rpcb_local_clnt/4 and the setting of rpcb_users? Otherwise, how do you guarantee that rpcb_users != 0 implies rpbc_local_clnt/4 != NULL?
We check rpcb_users under spinlock. Gain spinlock forces memory barrier, doesn't it? -- Best regards, Stanislav Kinsbursky