Re: [PATCH] hwrng: ks-sa - fix runtime pm imbalance on error

[Herbert Xu]

On Wed, May 20, 2020 at 12:45:56PM -0400, stern@xxxxxxxxxxxxxxxxxxx wrote:
> On Wed, May 20, 2020 at 03:42:17PM +0000, Sverdlin, Alexander (Nokia - DE/Ulm) wrote:
> > Hello Dinghao,
> > 
> > On Wed, 2020-05-20 at 21:29 +0800, Dinghao Liu wrote:
> > > pm_runtime_get_sync() increments the runtime PM usage counter even
> > > the call returns an error code. Thus a pairing decrement is needed
> > > on the error handling path to keep the counter balanced.
> > 
> > I believe, this is the wrong place for such kind of fix.
> > pm_runtime_get_sync() has obviously a broken semantics with regards to
> > your observation but no other driver does what you propose.
> 
> Look again.  For example, see what usb_autoresume_device() in 
> drivers/usb/core/driver.c does.

However, there seems to be some disagreement as to what to do
when pm_runtime_get_sync fails.  Your driver chooses to call
put_sync while others prefer pm_runtime_put_noidle (e.g., see
drivers/base/power/runtime.c).

This API does seem to be in a bit of a mess.

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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