Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it

Matthew Wilcox <[email protected]> wrote:

> > Ok. For SMP-safety, it's important that any architecture that can't do 
> > this needs to _share_ the same spinlock (on SMP only, of course) that it 
> > uses for the bitops. 
> 
> That doesn't help, since assignment can't be guarded by any lock.

It's not a problem for workqueues, since the only direct assignment to the
management member variable is during initialisation.

But in general cmpxchg() might be a problem with respect to assignment.

atomic_cmpxchg() should be safe wrt atomic_set().

David
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• References:
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Matthew Wilcox <[email protected]>
  • [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: David Howells <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Christoph Lameter <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Linus Torvalds <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Al Viro <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Linus Torvalds <[email protected]>

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