linux-kernel - Re: [RFC 01/10] drm: Track clients by tgid and not tid

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Date:   Tue, 14 Mar 2023 16:33:03 +0100
From:   Christian König <christian.koenig@....com>
To:     Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Dave Airlie <airlied@...hat.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Rob Clark <robdclark@...omium.org>,
        Stéphane Marchesin <marcheu@...omium.org>,
        "T . J . Mercier" <tjmercier@...gle.com>, Kenny.Ho@....com,
        Brian Welty <brian.welty@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Zack Rusin <zackr@...are.com>,
        linux-graphics-maintainer@...are.com,
        Alex Deucher <alexander.deucher@....com>
Subject: Re: [RFC 01/10] drm: Track clients by tgid and not tid

Am 14.03.23 um 15:18 schrieb Tvrtko Ursulin:
> From: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
>
> Thread group id (aka pid from userspace point of view) is a more
> interesting thing to show as an owner of a DRM fd, so track and show that
> instead of the thread id.
>
> In the next patch we will make the owner updated post file descriptor
> handover, which will also be tgid based to avoid ping-pong when multiple
> threads access the fd.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
> Cc: Zack Rusin <zackr@...are.com>
> Cc: linux-graphics-maintainer@...are.com
> Cc: Alex Deucher <alexander.deucher@....com>
> Cc: "Christian König" <christian.koenig@....com>
> Reviewed-by: Zack Rusin <zackr@...are.com>

Reviewed-by: Christian König <christian.koenig@....com>

Should we push the already reviewed cleanups like this one to 
drm-misc-next? That makes sense even without the rest of the 
functionality and reduce the amount of patches re-send.

Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 2 +-
>   drivers/gpu/drm/drm_debugfs.c           | 4 ++--
>   drivers/gpu/drm/drm_file.c              | 2 +-
>   drivers/gpu/drm/vmwgfx/vmwgfx_gem.c     | 2 +-
>   4 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index d8e683688daa..863cb668e000 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -969,7 +969,7 @@ static int amdgpu_debugfs_gem_info_show(struct seq_file *m, void *unused)
>   		 * Therefore, we need to protect this ->comm access using RCU.
>   		 */
>   		rcu_read_lock();
> -		task = pid_task(file->pid, PIDTYPE_PID);
> +		task = pid_task(file->pid, PIDTYPE_TGID);
>   		seq_printf(m, "pid %8d command %s:\n", pid_nr(file->pid),
>   			   task ? task->comm : "<unknown>");
>   		rcu_read_unlock();
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index 4f643a490dc3..4855230ba2c6 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -80,7 +80,7 @@ static int drm_clients_info(struct seq_file *m, void *data)
>   	seq_printf(m,
>   		   "%20s %5s %3s master a %5s %10s\n",
>   		   "command",
> -		   "pid",
> +		   "tgid",
>   		   "dev",
>   		   "uid",
>   		   "magic");
> @@ -94,7 +94,7 @@ static int drm_clients_info(struct seq_file *m, void *data)
>   		bool is_current_master = drm_is_current_master(priv);
>   
>   		rcu_read_lock(); /* locks pid_task()->comm */
> -		task = pid_task(priv->pid, PIDTYPE_PID);
> +		task = pid_task(priv->pid, PIDTYPE_TGID);
>   		uid = task ? __task_cred(task)->euid : GLOBAL_ROOT_UID;
>   		seq_printf(m, "%20s %5d %3d   %c    %c %5d %10u\n",
>   			   task ? task->comm : "<unknown>",
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index a51ff8cee049..c1018c470047 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -156,7 +156,7 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
>   	if (!file)
>   		return ERR_PTR(-ENOMEM);
>   
> -	file->pid = get_pid(task_pid(current));
> +	file->pid = get_pid(task_tgid(current));
>   	file->minor = minor;
>   
>   	/* for compatibility root is always authenticated */
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
> index d6baf73a6458..c0da89e16e6f 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
> @@ -241,7 +241,7 @@ static int vmw_debugfs_gem_info_show(struct seq_file *m, void *unused)
>   		 * Therefore, we need to protect this ->comm access using RCU.
>   		 */
>   		rcu_read_lock();
> -		task = pid_task(file->pid, PIDTYPE_PID);
> +		task = pid_task(file->pid, PIDTYPE_TGID);
>   		seq_printf(m, "pid %8d command %s:\n", pid_nr(file->pid),
>   			   task ? task->comm : "<unknown>");
>   		rcu_read_unlock();