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a=x4eqshVgHu-cdnggieHk:22 a=yPCof4ZbAAAA:8 a=hf0mEoRwjFS_tdgVxocA:9 a=QEXdDO2ut3YA:10 On 04/03/2026 09:43, Chaohai Chen wrote: > On Wed, Mar 04, 2026 at 09:20:25AM +0000, John Garry wrote: >> On 04/03/2026 07:57, Chaohai Chen wrote: >>> Previously, host_lock was used to prevent bit-set conflicts in async_scan, >>> but this approach introduced naked reads in some code paths. >>> >>> Convert async_scan from a bitfield to a bool type to eliminate bit-level >>> conflicts entirely. Use READ_ONCE() and WRITE_ONCE() to ensure proper >>> memory ordering on Alpha and satisfy KCSAN requirements. >> >> Is the shost->scan_mutex always held when shost->async_scan is read/written? >> > Yes. In theory, there is no need for READ-ONCE/WRITE-ONCE. Then I understand that in practice that there is no need (for READ/WRITE_ONCE), but having it will do no harm, as you mention below. > Plus, this belongs > to defensive programming. You could mention what this in the commit log. > And it indicates that this is a shared variable, > which means that this variable will be accessed by multiple threads and > concurrency issues need to be handled carefully. Reviewed-by: John Garry