Re: [RFC 1/2] refcount: add __cond_lock() for conditional lock refcount API

[Peter Zijlstra]

On Thu, Jun 30, 2022 at 09:59:33AM -0400, Alexander Aring wrote:
> This patch adds the __cond_lock() macro to refcounts conditional lock
> API. Currently sparse cannot detect the conditional lock handling of
> refcount_dec_and_lock() functionality and prints a context imbalance
> warning like:
> 
> warning: context imbalance in 'put_rsb' - unexpected unlock
> 
> with this patch and having the refcount_dec_and_lock() functionality
> inside the if condition to decide whenever doing unlock or not the
> warning disappears.
> 
> The patch follows a similar naming scheme like raw_spin_trylock() by
> adding a "raw_" prefix to refcount_dec_and_lock() functionality and
> introduce a macro for the replaced functions that uses __cond_lock()
> to signal that an acquire depends on the return value of the passed
> function.
> 
> A cast to bool seems to be necessary because __cond_lock() does return a
> non-boolean scalar type.

I hate the __cond_lock() think with a passions. Please just fix sparse
to not suck.