Messages in this thread | | | Date | Wed, 11 Nov 2015 19:44:27 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] arm64: bpf: add BPF XADD instruction |
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On Wed, Nov 11, 2015 at 07:31:28PM +0100, Peter Zijlstra wrote: > > Add new one that does 'fetch_and_add' ? What is the real use case it > > will be used for? > > Look at all the atomic_{add,dec}_return*() users in the kernel. A typical > example would be a reader-writer lock implementations. See > include/asm-generic/rwsem.h for examples.
Maybe a better example would be refcounting, where you free on 0.
if (!fetch_add(&obj->ref, -1)) free(obj);
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