[PATCH v9 1/9] drm/panic: Add drm panic locking

[John Ogness]

On 2024-03-07, Jocelyn Falempe <jfalempe at redhat.com> wrote:
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 39ef0a6addeb..c0bb91312fb2 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -38,6 +38,7 @@
>  #include <drm/drm_drv.h>
>  #include <drm/drm_framebuffer.h>
>  #include <drm/drm_gem_atomic_helper.h>
> +#include <drm/drm_panic.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_self_refresh_helper.h>
>  #include <drm/drm_vblank.h>
> @@ -3099,6 +3100,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
>  		}
>  	}
>  
> +	drm_panic_lock(state->dev);
>  	for_each_oldnew_plane_in_state(state, plane, old_plane_state, new_plane_state, i) {
>  		WARN_ON(plane->state != old_plane_state);
>  
> @@ -3108,6 +3110,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
>  		state->planes[i].state = old_plane_state;
>  		plane->state = new_plane_state;
>  	}
> +	drm_panic_unlock(state->dev);

Is there a reason irqsave/irqrestore variants are not used? Maybe this
code path is too hot?

By leaving interrupts enabled, there is the risk that a panic from
within any interrupt handler may block the drm panic handler.

John Ogness