Hi Dmitry,
Le 23/09/2024 à 12:28, Dmitry Osipenko a écrit :
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.
Honestly I don't see much value in printing "<undefined>" or any other default value (+ task->comm
is already printed above).
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
memdup_user_nul returns a NUL-terminated string so I don't see much need for using 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.
Sure, I can do that if others prefer this way too.
+ /** @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.
The locking also prevents concurrent modification.
};
/**
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.
Same as "const char *name;" vs "char name[...]": I don't mind updating the code as long as there's a
consensus.
+struct drm_set_name {
drm_set_name sounds very generic, IMO. Maybe drm_context_set_name?
drm_client_set_name?
(since other places use client, like drm_clients_info())
+ __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.
OK, I'll update based on your suggestion.
Thanks,
Pierre-Eric
