Messages in this thread | | | Date | Thu, 23 May 2013 16:36:53 +0200 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH 2/2] regmap: Make regmap-mmio usable from different contexts |
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On 05/23/2013 04:31 PM, Mark Brown wrote: > On Thu, May 23, 2013 at 04:20:27PM +0200, Lars-Peter Clausen wrote: >> On 05/23/2013 04:05 PM, Mark Brown wrote: > >>> This seems really invasive, why not just have the lock that gets passed >>> in point to a struct which has both the lock and the flags? As far as >>> the core is concerned the lock is just whatever data is required to do >>> the locking, the fact that it's actually two values is an implementation >>> detail of this locking implementation. > >> I think that won't work. spin_lock_irqsave() will write to the flags >> parameter before it has successfully taken the look. So if a process running >> on another CPU tries to acquire the the lock while it is already held we'll >> end up overwriting the flags. E.g: > > So you'd have to allocate a struct on the stack with a pointer and the > flags in it and initialise the pointer. Not awesome but not the end of > the world.
I'm not sure I understand what you mean. This needs to be done for each caller of a lock()/unlock() pair. We can't allocate the flags on the stack inside the lock() function since the stack will be gone once the function exits.
- Lars
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