On 8/16/21 3:34 PM, Maarten Lankhorst wrote:
Op 16-08-2021 om 15:30 schreef Thomas Hellström:
On 8/16/21 3:25 PM, Matthew Auld wrote:
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?
Yes, good catch. We should either just clear the -EDEADLK case, or not clear the error at all..
/Thomas
I believe not setting _err is a bug anyway. Why would you do such a loop without at least one err = ww_mutex_lock(&ww); ?
Infinite loop would catch that at first test.
OK, I'll skip the clearing then.
/Thomas
~Maarten
