On Mon, Jan 12, 2015 at 11:27 AM, Andres Freund <and...@2ndquadrant.com> wrote: > On 2015-01-12 11:03:42 -0500, Tom Lane wrote: >> Andres Freund <and...@2ndquadrant.com> writes: >> > While it might not be required for existing latch uses (I'm *not* sure >> > that's true) > > I think at least syncrep.c might not be correct. In SyncRepWakeQueue() > it sets PGPROC->syncRepState without the necessary barriers (via locks), > although it does use them in SyncRepWaitForLSN(). > > It is, perhaps surprisingly to many, not sufficient to take a spinlock, > change the flag, release it and then set the latch - the release alone > doesn't guarantee a sufficient barrier unless looking at the flag is > also protected by the spinlock.
I thought we decided that a spinlock acquire or release should be a full barrier. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
