On 9/20/24 12:06, 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@xxxxxxx> > --- > drivers/gpu/drm/drm_debugfs.c | 12 ++++++--- > drivers/gpu/drm/drm_file.c | 5 ++++ > drivers/gpu/drm/drm_ioctl.c | 48 +++++++++++++++++++++++++++++++++++ > include/drm/drm_file.h | 9 +++++++ > include/uapi/drm/drm.h | 17 +++++++++++++ > 5 files changed, 87 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c > index 6b239a24f1df..482e71160544 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 ?: ""); There should be a default name similar to task->comm, like "<undefined>" when not set. Perhaps also set name to task->comm by default. > 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..46dadbd1bb35 100644 > --- a/drivers/gpu/drm/drm_ioctl.c > +++ b/drivers/gpu/drm/drm_ioctl.c > @@ -540,6 +540,52 @@ 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 *user_ptr; > + char *new_name; > + size_t i, len; > + > + if (name->name_len > DRM_NAME_MAX_LEN) > + return -EINVAL; > + > + user_ptr = u64_to_user_ptr(name->name); > + > + new_name = memdup_user_nul(user_ptr, name->name_len); > + if (IS_ERR(new_name)) > + return PTR_ERR(new_name); > + > + len = strlen(new_name); strnlen > + if (len != name->name_len) { > + kfree(new_name); > + return -EINVAL; > + } > + > + /* > + * Filter out control char / spaces / new lines etc in the name > + * since it's going to be used in dmesg or fdinfo's output. > + */ > + for (i = 0; i < len; i++) { > + if (!isgraph(new_name[i])) > + new_name[i] = '-'; > + } > + > + 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; > + } > + 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 +656,8 @@ 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; I'd make the "name" string static, i.e. char name[DRM_NAME_MAX_LEN + 1]. That will prevent pointer deref troubles and no additional MM code bloating will be needed. > + /** @name_lock: Protects @name. */ > + struct mutex name_lock; And then this lock isn't strictly needed anymore and can be removed if "name" string is static. > }; > > /** > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h > index 16122819edfe..f5e92e4f909b 100644 > --- a/include/uapi/drm/drm.h > +++ b/include/uapi/drm/drm.h > @@ -1024,6 +1024,13 @@ struct drm_crtc_queue_sequence { > __u64 user_data; /* user data passed to event */ > }; > > +#define DRM_NAME_MAX_LEN 64 What about 63, to align data size to 64 bytes including the NULL byte. > +struct drm_set_name { drm_set_name sounds very generic, IMO. Maybe drm_context_set_name? > + __u64 name_len; > + __u64 name; > +}; > + > + > #if defined(__cplusplus) > } > #endif > @@ -1288,6 +1295,16 @@ 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. Don't refer to DMA_BUF_SET_NAME, explain what DRM_IOCTL_SET_NAME actually do. Tell that it sets the DRM context name and that chars are filtered. -- Best regards, Dmitry
