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Subject: RE: [RFC][PATCH 2/7] kref: Add kref_read()
Thread-Topic: [RFC][PATCH 2/7] kref: Add kref_read()
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> By the way, there are several sites where the use of
> atomic_t/atomic_wrap_t as a counter ventures beyond the standard (inc,
> dec, add, sub, read, set) operations we're planning on implementing
> for both refcount_t and stats_t. 

Speaking of non-fitting patterns. This one is quite common in networking code for refcounters:

if (atomic_cmpxchg(&cur->refcnt, 1, 0) == 1) {}
This is from  net/netfilter/nfnetlink_acct.c, but there are similar ones in other places. 

Also, simple atomic_dec() is used pretty much everywhere for counters, which we don’t have a straight match in refcount_t API.