From patchwork Fri Mar 4 08:26:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Thomas Hellstrom X-Patchwork-Id: 12768712 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82B73C433EF for ; Fri, 4 Mar 2022 08:27:14 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 050D310F880; Fri, 4 Mar 2022 08:27:06 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id AEE1110F87F; Fri, 4 Mar 2022 08:27:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646382424; x=1677918424; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0mI/+vaMOn6CKtYsGoLCEsNDrzBaXYH7Gw8jnO8Xox4=; b=e6NxHGnHykFV7hCIkg4Y2g+Kwo6Fhxy+lDD82of4jP+AL1yCmhDaR/fP Cmi7lpuC0g7d1zn7X+gkSvH2GC50QLjiwN6YvYjJUIoBSxM33vcabQFZu wLo3IJddJQfXiWaguYCrPV8tHJwp52Df6yin4jPepwZIk8Cjh/Xc6F0OH m+Vy2GM/lzInacSBvV53wvnaT3XZrlG/EFR/zGS+ZDIn8GsnaUkUQbMjQ SS9jGO173PNHv4KlQkrP0Zs4OY3CvfKoeS3UqM9rA3zEp4lpABA3Yykbb 9BneFDjC1Z6Laoamt1QP9s6+Tf3mXH7xo1a6sRp6+79llXANvcbJvtncV g==; X-IronPort-AV: E=McAfee;i="6200,9189,10275"; a="233887215" X-IronPort-AV: E=Sophos;i="5.90,154,1643702400"; d="scan'208";a="233887215" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2022 00:26:56 -0800 X-IronPort-AV: E=Sophos;i="5.90,154,1643702400"; d="scan'208";a="810380387" Received: from mmazarel-mobl.ger.corp.intel.com (HELO thellstr-mobl1.intel.com) ([10.249.254.59]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2022 00:26:54 -0800 From: =?utf-8?q?Thomas_Hellstr=C3=B6m?= To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Date: Fri, 4 Mar 2022 09:26:40 +0100 Message-Id: <20220304082641.308069-3-thomas.hellstrom@linux.intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220304082641.308069-1-thomas.hellstrom@linux.intel.com> References: <20220304082641.308069-1-thomas.hellstrom@linux.intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v3 2/3] drm/i915: Remove the vma refcount X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?q?Thomas_Hellstr=C3=B6m?= , matthew.auld@intel.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Now that i915_vma_parked() is taking the object lock on vma destruction, and the only user of the vma refcount, i915_gem_object_unbind() also takes the object lock, remove the vma refcount. v3: Documentation update. Signed-off-by: Thomas Hellström Reviewed-by: Niranjana Vishwanathapura --- drivers/gpu/drm/i915/i915_gem.c | 17 +++++++++++++---- drivers/gpu/drm/i915/i915_vma.c | 17 +++-------------- drivers/gpu/drm/i915/i915_vma.h | 14 -------------- drivers/gpu/drm/i915/i915_vma_types.h | 1 - 4 files changed, 16 insertions(+), 33 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index dd84ebabb50f..c26110abcc0b 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -151,14 +151,25 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj, break; } + /* + * Requiring the vm destructor to take the object lock + * before destroying a vma would help us eliminate the + * i915_vm_tryget() here, AND thus also the barrier stuff + * at the end. That's an easy fix, but sleeping locks in + * a kthread should generally be avoided. + */ ret = -EAGAIN; if (!i915_vm_tryget(vma->vm)) break; - /* Prevent vma being freed by i915_vma_parked as we unbind */ - vma = __i915_vma_get(vma); spin_unlock(&obj->vma.lock); + /* + * Since i915_vma_parked() takes the object lock + * before vma destruction, it won't race us here, + * and destroy the vma from under us. + */ + if (vma) { bool vm_trylock = !!(flags & I915_GEM_OBJECT_UNBIND_VM_TRYLOCK); ret = -EBUSY; @@ -180,8 +191,6 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj, ret = i915_vma_unbind(vma); } } - - __i915_vma_put(vma); } i915_vm_put(vma->vm); diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index cfa8a212b4dd..249a38585289 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -122,7 +122,6 @@ vma_create(struct drm_i915_gem_object *obj, if (vma == NULL) return ERR_PTR(-ENOMEM); - kref_init(&vma->ref); vma->ops = &vm->vma_ops; vma->obj = obj; vma->size = obj->base.size; @@ -1628,15 +1627,6 @@ void i915_vma_reopen(struct i915_vma *vma) __i915_vma_remove_closed(vma); } -void i915_vma_release(struct kref *ref) -{ - struct i915_vma *vma = container_of(ref, typeof(*vma), ref); - - i915_active_fini(&vma->active); - GEM_WARN_ON(vma->resource); - i915_vma_free(vma); -} - static void force_unbind(struct i915_vma *vma) { if (!drm_mm_node_allocated(&vma->node)) @@ -1665,7 +1655,9 @@ static void release_references(struct i915_vma *vma, bool vm_ddestroy) if (vm_ddestroy) i915_vm_resv_put(vma->vm); - __i915_vma_put(vma); + i915_active_fini(&vma->active); + GEM_WARN_ON(vma->resource); + i915_vma_free(vma); } /** @@ -1693,9 +1685,6 @@ static void release_references(struct i915_vma *vma, bool vm_ddestroy) * - vm->mutex * - obj->vma.lock * - gt->closed_lock - * - * A vma user can also temporarily keep the vma alive while holding a vma - * reference. */ void i915_vma_destroy_locked(struct i915_vma *vma) { diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h index 67ae7341c7e0..6034991d89fe 100644 --- a/drivers/gpu/drm/i915/i915_vma.h +++ b/drivers/gpu/drm/i915/i915_vma.h @@ -222,20 +222,6 @@ void i915_vma_unlink_ctx(struct i915_vma *vma); void i915_vma_close(struct i915_vma *vma); void i915_vma_reopen(struct i915_vma *vma); -static inline struct i915_vma *__i915_vma_get(struct i915_vma *vma) -{ - if (kref_get_unless_zero(&vma->ref)) - return vma; - - return NULL; -} - -void i915_vma_release(struct kref *ref); -static inline void __i915_vma_put(struct i915_vma *vma) -{ - kref_put(&vma->ref, i915_vma_release); -} - void i915_vma_destroy_locked(struct i915_vma *vma); void i915_vma_destroy(struct i915_vma *vma); diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h index eac36be184e5..be6e028c3b57 100644 --- a/drivers/gpu/drm/i915/i915_vma_types.h +++ b/drivers/gpu/drm/i915/i915_vma_types.h @@ -211,7 +211,6 @@ struct i915_vma { * handles (but same file) for execbuf, i.e. the number of aliases * that exist in the ctx->handle_vmas LUT for this vma. */ - struct kref ref; atomic_t open_count; atomic_t flags; /**