From mboxrd@z Thu Jan 1 00:00:00 1970 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 D2F64C61DBE for ; Wed, 26 Aug 2026 21:37:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0CF0310E1B8; Wed, 26 Aug 2026 21:37:12 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="ZAqhs0zh"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7697710E1B8 for ; Wed, 26 Aug 2026 21:37:10 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3A9E7438E3; Wed, 26 Aug 2026 21:37:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E62C91F00A3A; Wed, 26 Aug 2026 21:37:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787780230; bh=3EsLarGxS5eVmzhTN5pjdgYo6blgDtTIo7xvvVLPAVQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=ZAqhs0zhV5mY5IqTnVZUgFVBvnc8Am+aIRzl60f8nGWtkz2bDfVCedIPp70ucG0qq k13iE1Z3TpIjRNMGEP+X1fqC70oa4gom/xA7jJMBVkqhxdAzaeNwP/17+18JOgk8Xd P81DZyEcOJtjJZcdI9FVbvou4yXLQjlMmOBKZ99ilb2qs874QLZlWWYylaYSUVih7t sQBnDwpQ7zzvBecIztQGWT1pqCjZ7e9TmJ/ORg7WZ8bnWPHsnfZ8XtIlQFX49yIz2H urqQAulnZcVvdwNS9++6AfligoOYppxav18uPESLTf8asSomZ7eu2Upo99NGfvOyfD /jIiVaCmOIhUA== From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 16/16] drm/panfrost: Bump driver minor to reflect new DUMP IOCTL req field To: =?utf-8?b?QWRyacOhbiBMYXJ1bWJl?= Cc: dri-devel@lists.freedesktop.org In-Reply-To: <20260826-claude-fixes-v6-16-78119af409e7@collabora.com> References: <20260826-claude-fixes-v6-0-78119af409e7@collabora.com> <20260826-claude-fixes-v6-16-78119af409e7@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 26 Aug 2026 21:37:09 +0000 Message-Id: <20260826213709.E62C91F00A3A@smtp.kernel.org> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] Hardware performance counter initialization is skipped on new sess= ions due to an incorrect condition, leading to an MMU address space referen= ce count underflow and resource leak. -- commit 036d049b8b6f60dc9ba18742b07e01b404ef96c3 Author: Adri=C3=A1n Larumbe drm/panfrost: Fix races between perfcnt and reset sequence Formerly, the reset sequence would race with panfrost_mmu_as_put() when tearing down a perfcnt session. This commit introduces a read/write semaphore to govern access to the hardware at reset time, and expands the DRM uAPI for the perfcnt DUMP operation. > diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/dr= m/panfrost/panfrost_perfcnt.c > index b3f71d7fd82a9..7dcf27add7ae7 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c > +++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c [ ... ] > @@ -132,44 +206,20 @@ static int panfrost_perfcnt_enable_locked(struct pa= nfrost_device *pfdev, > gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_PERFCNT_SAMPLE_COMPLETED); > gpu_write(pfdev, GPU_CMD, GPU_CMD_PERFCNT_CLEAR); > =20 > - ret =3D panfrost_mmu_as_get(pfdev, perfcnt->mapping->mmu); > - if (ret < 0) > - goto err_vunmap; > - [ ... ] > - gpu_write(pfdev, GPU_PERFCNT_CFG, cfg); > - > - if (panfrost_has_hw_issue(pfdev, HW_ISSUE_8186)) > - gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0xffffffff); > + scoped_guard(rwsem_read, &pfdev->reset.lock) { > + if (perfcnt->reset_failed) { > + ret =3D panfrost_perfcnt_hw_enable(pfdev); > + if (ret) > + goto err_vunmap; > + } [Severity: High] Does this skip the initial hardware enablement on new sessions? Since perfcnt->reset_failed would be false initially, it seems panfrost_perfcnt_hw_enable() is bypassed entirely, which also means we miss taking the MMU AS reference via panfrost_mmu_as_get(). > + perfcnt->reset_happened =3D false; > + perfcnt->reset_failed =3D false; > + perfcnt->user =3D user; > + } > =20 > /* The BO ref is retained by the mapping. */ > drm_gem_object_put(&bo->base); [ ... ] > @@ -195,13 +245,15 @@ static int panfrost_perfcnt_disable_locked(struct p= anfrost_device *pfdev, > if (user !=3D perfcnt->user) > return -EINVAL; > =20 > - panfrost_perfcnt_hw_disable(pfdev); > + scoped_guard(rwsem_read, &pfdev->reset.lock) { > + panfrost_perfcnt_hw_disable(pfdev); > + panfrost_mmu_as_put(pfdev, perfcnt->mapping->mmu); [Severity: High] If panfrost_perfcnt_hw_enable() was skipped in panfrost_perfcnt_enable_locked(), will this unconditionally drop a reference that was never acquired? It looks like this could underflow the AS reference count, which would prevent subsequent allocations since a negative reference count isn't considered free. > + perfcnt->user =3D NULL; > + } > =20 > - perfcnt->user =3D NULL; > drm_gem_vunmap(&perfcnt->mapping->obj->base.base, &map); [ ... ] --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260826-claude-fix= es-v6-0-78119af409e7@collabora.com?part=3D16