Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: 2.4.18 Preempt Freezeups | Date | Sun, 17 Mar 2002 02:14:14 +0100 |
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On March 17, 2002 02:13 am, yodaiken@fsmlabs.com wrote: > On Sun, Mar 17, 2002 at 01:33:04AM +0100, Daniel Phillips wrote: > > On March 16, 2002 01:40 am, yodaiken@fsmlabs.com wrote: > > > > > > Without preempt: > > > x = movefrom processor register; > // if preemption is on, we can be preempted and restart > // on another processor so x will be wrong > > > do_something with x > > > > > > is safe in SMP > > > With [preempt] it requires a lock. > > > > It must be a trick question. Why would it? > > See comment.
Which processor register were you thinking of? Surely not anything in the general register set, and otherwise, it's just another example of per-cpu data. It needs to be protected, and the protection is lightweight.
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