On Mon, 16 Aug 2021 at 09:49, Thomas Hellström
<thomas.hellstrom@xxxxxxxxxxxxxxx> wrote:
>
> It's only used by the for_i915_gem_ww() macro and we can use
> the (typically) on-stack _err variable in its place.
>
> While initially setting the _err variable to -EDEADLK to enter the
> loop, we clear it before actually entering using fetch_and_zero() to
> avoid empty loops or code not setting the _err variable running forever.
>
> Suggested-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_ww.h | 23 ++++++++---------------
> 1 file changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_ww.h b/drivers/gpu/drm/i915/i915_gem_ww.h
> index f6b1a796667b..98348b1e6182 100644
> --- a/drivers/gpu/drm/i915/i915_gem_ww.h
> +++ b/drivers/gpu/drm/i915/i915_gem_ww.h
> @@ -7,12 +7,13 @@
>
> #include <drm/drm_drv.h>
>
> +#include "i915_utils.h"
> +
> struct i915_gem_ww_ctx {
> struct ww_acquire_ctx ctx;
> struct list_head obj_list;
> struct drm_i915_gem_object *contended;
> - unsigned short intr;
> - unsigned short loop;
> + bool intr;
> };
>
> void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ctx, bool intr);
> @@ -23,28 +24,20 @@ void i915_gem_ww_unlock_single(struct drm_i915_gem_object *obj);
> /* Internal functions used by the inlines! Don't use. */
> static inline int __i915_gem_ww_fini(struct i915_gem_ww_ctx *ww, int err)
> {
> - ww->loop = 0;
> if (err == -EDEADLK) {
> err = i915_gem_ww_ctx_backoff(ww);
> if (!err)
> - ww->loop = 1;
> + err = -EDEADLK;
> }
>
> - if (!ww->loop)
> + if (err != -EDEADLK)
> i915_gem_ww_ctx_fini(ww);
>
> return err;
> }
>
> -static inline void
> -__i915_gem_ww_init(struct i915_gem_ww_ctx *ww, bool intr)
> -{
> - i915_gem_ww_ctx_init(ww, intr);
> - ww->loop = 1;
> -}
> -
> -#define for_i915_gem_ww(_ww, _err, _intr) \
> - for (__i915_gem_ww_init(_ww, _intr); (_ww)->loop; \
> +#define for_i915_gem_ww(_ww, _err, _intr) \
> + for (i915_gem_ww_ctx_init(_ww, _intr), (_err) = -EDEADLK; \
> + fetch_and_zero(&_err) == -EDEADLK; \
Doesn't this now hide "normal" errors, like say get_pages() returning
-ENOSPC or so?
> _err = __i915_gem_ww_fini(_ww, _err))
> -
> #endif
> --
> 2.31.1
>
