Messages in this thread | | | Subject | Re: rpc_xprt_debugfs_register() - atomic_inc_return() usage | From | Shuah Khan <> | Date | Thu, 21 Jan 2021 11:01:09 -0700 |
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On 1/21/21 10:56 AM, Trond Myklebust wrote: > On Wed, 2021-01-20 at 16:52 -0700, Shuah Khan wrote: >> Hi Anna and Trond, >> >> I came across the following while reviewing atomic_inc_return() >> usages >> that cast return value to unsigned >> >> rpc_xprt_debugfs_register()'s atomic_inc_return() usage looks a bit >> odd. >> >> - cur_id isn't initialized >> - id = (unsigned int)atomic_inc_return(&cur_id); >> >> Please note that id is int. Is it expected that cur_id could >> overflow? >> Is there a maximum limit for this value? >> > > Yes, we do expect cur_id to eventually overflow (once you have created > 2 billion RPC client instances), however the atomic increment > operations are expected to handle this correctly according to the > maintainers (I already asked them in a different context). Furthermore, > the code itself doesn't care about strict sequentiality. All it wants > from the counter is uniqueness, with that uniqueness condition actually > being enforced by the subsequent debugfs_create_file() call. > > IOW: I don't think this is a real problem. >
Great. Thank you for a detailed explanation.
-- Shuah
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