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
