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 58BF2C7115B for ; Mon, 23 Jun 2025 06:21:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AC83610E186; Mon, 23 Jun 2025 06:21:31 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="Oi1fKtdQ"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 535C610E186 for ; Mon, 23 Jun 2025 06:21:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1750659689; bh=S+lNeumD5H26uvwBaO1T9jxSaUHSIdHOJ7k2YDYX5ko=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Oi1fKtdQPGMEkUueIz6ysRvX8eHqYDjvTnWVx7KWdb0ZvZZFn8J20VTXlIwQD7HzW aMo0dCM1vDxoijZBKkLgJh/Qg6IyhZN15f7BfVsTO+PuRSGQ0jurF9PPWL8eU/Boom mWXGEAB8bjagDEbd5mTPCHFxrAj6gRRCDISSFQtUVaNNeiGRgIWCbHvj+XbVmuLAp2 9qOAHRptO6K3RRKTYHbvH5ba+H925sWAuLzg7r8VhVKZQAy6MHpk4xA+9Z9xlRbF9c 1lxVoINs9CgNkBbjX3QGAHH+wgSg6o6cuSF9o27e1t5axiPqxOUwGr8eTa4SIp15V6 ZMlnoY6tuCe/A== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:16f1:973:959b:9b0c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 96F0417E0EC0; Mon, 23 Jun 2025 08:21:28 +0200 (CEST) Date: Mon, 23 Jun 2025 08:21:22 +0200 From: Boris Brezillon To: Chia-I Wu Cc: Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] panthor: save panthor_file in panthor_group Message-ID: <20250623082122.62f69579@fedora> In-Reply-To: <20250620235053.164614-3-olvaffe@gmail.com> References: <20250620235053.164614-1-olvaffe@gmail.com> <20250620235053.164614-3-olvaffe@gmail.com> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 20 Jun 2025 16:50:51 -0700 Chia-I Wu wrote: > We would like to access panthor_file from panthor_group on gpu errors. > Because panthour_group can outlive drm_file, add refcount to > panthor_file to ensure its lifetime. I'm not a huge fan of refcounting panthor_file because people tend to put resource they expect to be released when the last handle goes away, and if we don't refcount these sub-resources they might live longer than they are meant to. Also not a huge fan of the circular referencing that exists between file and groups after this change. How about we move the process info to a sub-object that's refcounted and let both panthor_file and panthor_group take a ref on this object instead? > > Signed-off-by: Chia-I Wu > --- > drivers/gpu/drm/panthor/panthor_device.h | 16 ++++++++++++++++ > drivers/gpu/drm/panthor/panthor_drv.c | 15 ++++++++++++++- > drivers/gpu/drm/panthor/panthor_mmu.c | 1 + > drivers/gpu/drm/panthor/panthor_sched.c | 6 ++++++ > 4 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h > index 4fc7cf2aeed57..75ae6fd3a5128 100644 > --- a/drivers/gpu/drm/panthor/panthor_device.h > +++ b/drivers/gpu/drm/panthor/panthor_device.h > @@ -256,8 +256,24 @@ struct panthor_file { > > /** @stats: cycle and timestamp measures for job execution. */ > struct panthor_gpu_usage stats; > + > + /** @refcount: ref count of this file */ > + struct kref refcount; > }; > > +static inline struct panthor_file *panthor_file_get(struct panthor_file *pfile) > +{ > + kref_get(&pfile->refcount); > + return pfile; > +} > + > +void panthor_file_release(struct kref *kref); > + > +static inline void panthor_file_put(struct panthor_file *pfile) > +{ > + kref_put(&pfile->refcount, panthor_file_release); > +} > + > int panthor_device_init(struct panthor_device *ptdev); > void panthor_device_unplug(struct panthor_device *ptdev); > > diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c > index 775a66c394544..aea9609684b77 100644 > --- a/drivers/gpu/drm/panthor/panthor_drv.c > +++ b/drivers/gpu/drm/panthor/panthor_drv.c > @@ -1393,6 +1393,16 @@ static int panthor_ioctl_set_user_mmio_offset(struct drm_device *ddev, > return 0; > } > > +void panthor_file_release(struct kref *kref) > +{ > + struct panthor_file *pfile = > + container_of(kref, struct panthor_file, refcount); > + > + WARN_ON(pfile->vms || pfile->groups); > + > + kfree(pfile); > +} > + > static int > panthor_open(struct drm_device *ddev, struct drm_file *file) > { > @@ -1426,6 +1436,8 @@ panthor_open(struct drm_device *ddev, struct drm_file *file) > if (ret) > goto err_destroy_vm_pool; > > + kref_init(&pfile->refcount); > + > file->driver_priv = pfile; > return 0; > > @@ -1442,10 +1454,11 @@ panthor_postclose(struct drm_device *ddev, struct drm_file *file) > { > struct panthor_file *pfile = file->driver_priv; > > + /* destroy vm and group handles now to avoid circular references */ > panthor_group_pool_destroy(pfile); > panthor_vm_pool_destroy(pfile); > > - kfree(pfile); > + panthor_file_put(pfile); > } > > static const struct drm_ioctl_desc panthor_drm_driver_ioctls[] = { > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c > index b39ea6acc6a96..ccbcfe11420ac 100644 > --- a/drivers/gpu/drm/panthor/panthor_mmu.c > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c > @@ -1604,6 +1604,7 @@ void panthor_vm_pool_destroy(struct panthor_file *pfile) > > xa_destroy(&pfile->vms->xa); > kfree(pfile->vms); > + pfile->vms = NULL; > } > > /** > diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c > index a2248f692a030..485072904cd7d 100644 > --- a/drivers/gpu/drm/panthor/panthor_sched.c > +++ b/drivers/gpu/drm/panthor/panthor_sched.c > @@ -535,6 +535,9 @@ struct panthor_group { > /** @ptdev: Device. */ > struct panthor_device *ptdev; > > + /** @pfile: File this group is created from. */ > + struct panthor_file *pfile; > + > /** @vm: VM bound to the group. */ > struct panthor_vm *vm; > > @@ -919,6 +922,7 @@ static void group_release_work(struct work_struct *work) > panthor_kernel_bo_destroy(group->syncobjs); > > panthor_vm_put(group->vm); > + panthor_file_put(group->pfile); > kfree(group); > } > > @@ -3467,6 +3471,8 @@ int panthor_group_create(struct panthor_file *pfile, > INIT_WORK(&group->tiler_oom_work, group_tiler_oom_work); > INIT_WORK(&group->release_work, group_release_work); > > + group->pfile = panthor_file_get(pfile); > + > group->vm = panthor_vm_pool_get_vm(pfile->vms, group_args->vm_id); > if (!group->vm) { > ret = -EINVAL;