Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 4.19 56/81] kernel/sysctl.c: do not override max_threads provided by userspace | Date | Thu, 17 Oct 2019 11:25:47 +0000 |
| |
From: Michal Hocko > Sent: 17 October 2019 12:05 ... > > Plus, I don't see any locking here, should this be WRITE_ONCE() at > > minimum? > > Why would that matter? Do you expect several root processes race to set > the value?
One of them wins. No one is going to notice is the value is set an extra time.
WRITE_ONCE() is rarely required. Probably only if other code is going to update the value after seeing the first write. (eg if you are unlocking a mutex - although they have to be more complex)
READ_ONCE() is a different matter. IMHO the compiler shouldn't be allowed to do more reads than the source requests.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
| |