[PATCH v2 1/3] drm: add DRM_SET_NAME ioctl
Tvrtko Ursulin
tvrtko.ursulin at igalia.com
Mon Sep 16 14:35:27 UTC 2024
On 16/09/2024 14:32, Pierre-Eric Pelloux-Prayer wrote:
> Giving the opportunity to userspace to associate a free-form
> name with a drm_file struct is helpful for tracking and debugging.
>
> This is similar to the existing DMA_BUF_SET_NAME ioctl.
>
> Access to name is protected by a mutex, and the 'clients' debugfs
> file has been updated to print it.
>
> Userspace MR to use this ioctl:
> https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/1428
>
> The string passed by userspace is filtered a bit, to avoid messing
> output when it's going to be printed (in dmesg, fdinfo, etc):
> * all chars failing isgraph() are replaced by '-'
> * if a 0-length string is passed the name is cleared
>
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
> ---
> drivers/gpu/drm/drm_debugfs.c | 12 ++++++----
> drivers/gpu/drm/drm_file.c | 5 +++++
> drivers/gpu/drm/drm_ioctl.c | 42 +++++++++++++++++++++++++++++++++++
> include/drm/drm_file.h | 9 ++++++++
> include/uapi/drm/drm.h | 14 ++++++++++++
> 5 files changed, 78 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index 6b239a24f1df..b7492225ae88 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -78,12 +78,13 @@ static int drm_clients_info(struct seq_file *m, void *data)
> kuid_t uid;
>
> seq_printf(m,
> - "%20s %5s %3s master a %5s %10s\n",
> + "%20s %5s %3s master a %5s %10s %20s\n",
> "command",
> "tgid",
> "dev",
> "uid",
> - "magic");
> + "magic",
> + "name");
>
> /* dev->filelist is sorted youngest first, but we want to present
> * oldest first (i.e. kernel, servers, clients), so walk backwardss.
> @@ -94,19 +95,22 @@ static int drm_clients_info(struct seq_file *m, void *data)
> struct task_struct *task;
> struct pid *pid;
>
> + mutex_lock(&priv->name_lock);
> rcu_read_lock(); /* Locks priv->pid and pid_task()->comm! */
> pid = rcu_dereference(priv->pid);
> task = pid_task(pid, PIDTYPE_TGID);
> uid = task ? __task_cred(task)->euid : GLOBAL_ROOT_UID;
> - seq_printf(m, "%20s %5d %3d %c %c %5d %10u\n",
> + seq_printf(m, "%20s %5d %3d %c %c %5d %10u %20s\n",
> task ? task->comm : "<unknown>",
> pid_vnr(pid),
> priv->minor->index,
> is_current_master ? 'y' : 'n',
> priv->authenticated ? 'y' : 'n',
> from_kuid_munged(seq_user_ns(m), uid),
> - priv->magic);
> + priv->magic,
> + priv->name ? priv->name : "");
> rcu_read_unlock();
> + mutex_unlock(&priv->name_lock);
> }
> mutex_unlock(&dev->filelist_mutex);
> return 0;
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 01fde94fe2a9..e9dd0e90a1f9 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -158,6 +158,7 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
>
> spin_lock_init(&file->master_lookup_lock);
> mutex_init(&file->event_read_lock);
> + mutex_init(&file->name_lock);
>
> if (drm_core_check_feature(dev, DRIVER_GEM))
> drm_gem_open(dev, file);
> @@ -259,6 +260,10 @@ void drm_file_free(struct drm_file *file)
> WARN_ON(!list_empty(&file->event_list));
>
> put_pid(rcu_access_pointer(file->pid));
> +
> + mutex_destroy(&file->name_lock);
> + kfree(file->name);
> +
> kfree(file);
> }
>
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 51f39912866f..b7d7bede0ab3 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -540,6 +540,46 @@ int drm_version(struct drm_device *dev, void *data,
> return err;
> }
>
> +static int drm_set_name(struct drm_device *dev, void *data,
> + struct drm_file *file_priv)
> +{
> + struct drm_set_name *name = data;
> + void *user_ptr;
__user as kernel test robot reminds us.
> + char *new_name;
> + size_t i, len;
> +
> + if (name->name_len >= NAME_MAX)
> + return -EINVAL;
Maybe it is a bit unsubstantiated, but I am leaning towards a feeling of
lets define own smaller limit, like dma-buf does. If 32 is deemed too
restrictive make it larger but 255 feels unnecessary. But I don't feel
to strongly about this so if people insist we need the names this long
then so be it.
> +
> + user_ptr = u64_to_user_ptr(name->name);
> +
> + new_name = memdup_user_nul(user_ptr, name->name_len);
> +
Nit: I'd zap this blank line since it is breaking a logical group.
> + if (IS_ERR(new_name))
> + return PTR_ERR(new_name);
> +
> + /* Filter out control char / spaces / new lines etc in the name
> + * since it's going to be used in dmesg or fdinfo's output.
> + */
Nit: Preferred kernel style for multi-line comments is:
/*
* Comment
*/
Unless amdgpu preferes to stick with the above. I think I've seen both
used so don't know.
> + len = strlen(new_name);
Made me think if it is worth cross-checking against name->name_len and
reject on mismatch? Probably yes.
> + for (i = 0; i < len; i++) {
> + if (!isgraph(new_name[i]))
> + new_name[i] = '-';
> + }
For completeness, alternative is to -EINVAL it. I have no strong
opinions either way.
> +
> + mutex_lock(&file_priv->name_lock);
> + kfree(file_priv->name);
> + if (len > 0) {
> + file_priv->name = new_name;
> + } else {
> + kfree(new_name);
> + file_priv->name = NULL;
FWIW you could not bother allocating new_file in this case.
Regards,
Tvrtko
> + }
> + mutex_unlock(&file_priv->name_lock);
> +
> + return 0;
> +}
> +
> static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
> {
> /* ROOT_ONLY is only for CAP_SYS_ADMIN */
> @@ -610,6 +650,8 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_HANDLE_TO_FD, drm_prime_handle_to_fd_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_FD_TO_HANDLE, drm_prime_fd_to_handle_ioctl, DRM_RENDER_ALLOW),
>
> + DRM_IOCTL_DEF(DRM_IOCTL_SET_NAME, drm_set_name, DRM_RENDER_ALLOW),
> +
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPLANERESOURCES, drm_mode_getplane_res, 0),
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETCRTC, drm_mode_getcrtc, 0),
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETCRTC, drm_mode_setcrtc, DRM_MASTER),
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 8c0030c77308..df26eee8f79c 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -388,6 +388,15 @@ struct drm_file {
> * Per-file buffer caches used by the PRIME buffer sharing code.
> */
> struct drm_prime_file_private prime;
> +
> + /**
> + * @name:
> + *
> + * Userspace-provided name; useful for accounting and debugging.
> + */
> + const char *name;
> + /** @name_lock: Protects @name. */
> + struct mutex name_lock;
> };
>
> /**
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 16122819edfe..fc62bb21f79e 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -1024,6 +1024,12 @@ struct drm_crtc_queue_sequence {
> __u64 user_data; /* user data passed to event */
> };
>
> +struct drm_set_name {
> + __u64 name_len;
> + __u64 name;
> +};
> +
> +
> #if defined(__cplusplus)
> }
> #endif
> @@ -1288,6 +1294,14 @@ extern "C" {
> */
> #define DRM_IOCTL_MODE_CLOSEFB DRM_IOWR(0xD0, struct drm_mode_closefb)
>
> +/**
> + * DRM_IOCTL_SET_NAME - Attach a name to a drm_file
> + *
> + * This ioctl is similar to DMA_BUF_SET_NAME - it allows for easier tracking
> + * and debugging.
> + */
> +#define DRM_IOCTL_SET_NAME DRM_IOWR(0xD1, struct drm_set_name)
> +
> /*
> * Device specific ioctls should only be in their respective headers
> * The device specific ioctl range is from 0x40 to 0x9f.
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