Hi Maxime, On Tue, 19 Aug 2025 18:01:37 +0200 Luca Ceresoli <luca.ceres...@bootlin.com> wrote:
> Hi Maxime, > > On Tue, 19 Aug 2025 15:47:06 +0200 > Maxime Ripard <mrip...@kernel.org> wrote: > > > > +/** > > > + * drm_for_each_bridge_in_chain_scoped - iterate over all bridges > > > attached > > > + * to an encoder > > > + * @encoder: the encoder to iterate bridges on > > > + * @bridge: a bridge pointer updated to point to the current bridge at > > > each > > > + * iteration > > > + * > > > + * Iterate over all bridges present in the bridge chain attached to > > > @encoder. > > > + * > > > + * Automatically gets/puts the bridge reference while iterating, and puts > > > + * the reference even if returning or breaking in the middle of the loop. > > > + */ > > > +#define drm_for_each_bridge_in_chain_scoped(encoder, bridge) > > > \ > > > + for (struct drm_bridge *bridge __free(drm_bridge_put) = \ > > > + drm_bridge_chain_get_first_bridge(encoder); \ > > > > So my understanding is that the initial value of bridge would be cleaned > > up with drm_bridge_put... > > > > > + bridge; \ > > > + bridge = drm_bridge_get_next_bridge_and_put(bridge)) > > > > ... but also when iterating? > > > > So if we have more than 0 values, we put two references? > > No, this is not the case. The __free action is executed only when > exiting the entire for loop, not a single iteration. > > This is consistent with the fact that the loop variable is persistent > across iterations. PS: here's the C language spec reference: > 6.8.5.3 The for statement > The statement > for ( clause-1 ; expression-2 ; expression-3 ) statement > behaves as follows: > [...] > If clause-1 is a declaration, the scope of any identifiers it declares > is the remainder of the declaration and the entire loop https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf https://rgambord.github.io/c99-doc/sections/6/8/5/3/index.html Best regards, Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
