Messages in this thread | | | Subject | Re: [PATCH 1/3] sched, timer: Remove usages of ACCESS_ONCE in the scheduler | From | Jason Low <> | Date | Tue, 14 Apr 2015 19:12:33 -0700 |
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Hi Steven,
On Tue, 2015-04-14 at 19:59 -0400, Steven Rostedt wrote: > On Tue, 14 Apr 2015 16:09:44 -0700 > Jason Low <jason.low2@hp.com> wrote: > > > > @@ -2088,7 +2088,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) > > > > static void reset_ptenuma_scan(struct task_struct *p) > > { > > - ACCESS_ONCE(p->mm->numa_scan_seq)++; > > + WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1); > > Is the READ_ONCE() inside the WRITE_ONCE() really necessary?
Yeah, I think so to be safe, otherwise, the access of p->mm->numa_scan_seq in the 2nd parameter doesn't have the volatile cast.
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