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Message-Id: <20221019173254.3361334-9-tvrtko.ursulin@linux.intel.com>
Date: Wed, 19 Oct 2022 18:32:45 +0100
From: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To: Intel-gfx@...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,
Christian König <christian.koenig@....com>,
Brian Welty <brian.welty@...el.com>,
Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Subject: [RFC 08/17] drm: Allow for migration of clients
From: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Add a helper which allows migrating the tracked client from one process to
another.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
---
drivers/gpu/drm/drm_cgroup.c | 111 ++++++++++++++++++++++++++++++-----
include/drm/drm_clients.h | 7 +++
include/drm/drm_file.h | 1 +
3 files changed, 103 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/drm_cgroup.c b/drivers/gpu/drm/drm_cgroup.c
index 7ed9c7150cae..59b730ed1334 100644
--- a/drivers/gpu/drm/drm_cgroup.c
+++ b/drivers/gpu/drm/drm_cgroup.c
@@ -8,9 +8,21 @@
static DEFINE_XARRAY(drm_pid_clients);
+static void
+__del_clients(struct drm_pid_clients *clients, struct drm_file *file_priv)
+{
+ list_del_rcu(&file_priv->clink);
+ if (atomic_dec_and_test(&clients->num)) {
+ xa_erase(&drm_pid_clients, (unsigned long)file_priv->cpid);
+ kfree_rcu(clients, rcu);
+ }
+
+ put_pid(file_priv->cpid);
+ file_priv->cpid = NULL;
+}
+
void drm_clients_close(struct drm_file *file_priv)
{
- unsigned long pid = (unsigned long)file_priv->pid;
struct drm_device *dev = file_priv->minor->dev;
struct drm_pid_clients *clients;
@@ -19,19 +31,32 @@ void drm_clients_close(struct drm_file *file_priv)
if (!dev->driver->cg_ops)
return;
- clients = xa_load(&drm_pid_clients, pid);
- list_del_rcu(&file_priv->clink);
- if (atomic_dec_and_test(&clients->num)) {
- xa_erase(&drm_pid_clients, pid);
- kfree_rcu(clients, rcu);
+ clients = xa_load(&drm_pid_clients, (unsigned long)file_priv->cpid);
+ if (WARN_ON_ONCE(!clients))
+ return;
- /*
- * FIXME: file_priv is not RCU protected so we add this hack
- * to avoid any races with code which walks clients->file_list
- * and accesses file_priv.
- */
- synchronize_rcu();
+ __del_clients(clients, file_priv);
+
+ /*
+ * FIXME: file_priv is not RCU protected so we add this hack
+ * to avoid any races with code which walks clients->file_list
+ * and accesses file_priv.
+ */
+ synchronize_rcu();
+}
+
+static struct drm_pid_clients *__alloc_clients(void)
+{
+ struct drm_pid_clients *clients;
+
+ clients = kmalloc(sizeof(*clients), GFP_KERNEL);
+ if (clients) {
+ atomic_set(&clients->num, 0);
+ INIT_LIST_HEAD(&clients->file_list);
+ init_rcu_head(&clients->rcu);
}
+
+ return clients;
}
int drm_clients_open(struct drm_file *file_priv)
@@ -48,12 +73,9 @@ int drm_clients_open(struct drm_file *file_priv)
clients = xa_load(&drm_pid_clients, pid);
if (!clients) {
- clients = kmalloc(sizeof(*clients), GFP_KERNEL);
+ clients = __alloc_clients();
if (!clients)
return -ENOMEM;
- atomic_set(&clients->num, 0);
- INIT_LIST_HEAD(&clients->file_list);
- init_rcu_head(&clients->rcu);
new_client = true;
}
atomic_inc(&clients->num);
@@ -69,9 +91,66 @@ int drm_clients_open(struct drm_file *file_priv)
}
}
+ file_priv->cpid = get_pid(file_priv->pid);
+
return 0;
}
+void drm_clients_migrate(struct drm_file *file_priv)
+{
+ struct drm_device *dev = file_priv->minor->dev;
+ struct drm_pid_clients *existing_clients;
+ struct drm_pid_clients *clients, *spare;
+ struct pid *pid = task_pid(current);
+
+ if (!dev->driver->cg_ops)
+ return;
+
+ // TODO: only do this if drmcs level property allows it?
+
+ spare = __alloc_clients();
+ if (WARN_ON(!spare))
+ return;
+
+ mutex_lock(&dev->filelist_mutex);
+ rcu_read_lock();
+
+ existing_clients = xa_load(&drm_pid_clients, (unsigned long)pid);
+ clients = xa_load(&drm_pid_clients, (unsigned long)file_priv->cpid);
+
+ if (WARN_ON_ONCE(!clients))
+ goto out_unlock;
+ else if (clients == existing_clients)
+ goto out_unlock;
+
+ __del_clients(clients, file_priv);
+ smp_mb(); /* hmmm? del_rcu followed by add_rcu? */
+
+ if (!existing_clients) {
+ void *xret;
+
+ xret = xa_store(&drm_pid_clients, (unsigned long)pid, spare,
+ GFP_KERNEL);
+ if (WARN_ON(xa_err(xret)))
+ goto out_unlock;
+ clients = spare;
+ spare = NULL;
+ } else {
+ clients = existing_clients;
+ }
+
+ atomic_inc(&clients->num);
+ list_add_tail_rcu(&file_priv->clink, &clients->file_list);
+ file_priv->cpid = get_pid(pid);
+
+out_unlock:
+ rcu_read_unlock();
+ mutex_unlock(&dev->filelist_mutex);
+
+ kfree(spare);
+}
+EXPORT_SYMBOL_GPL(drm_clients_migrate);
+
unsigned int drm_pid_priority_levels(struct pid *pid, bool *non_uniform)
{
unsigned int min_levels = UINT_MAX;
diff --git a/include/drm/drm_clients.h b/include/drm/drm_clients.h
index 10d21138f7af..3a0b1cdb338f 100644
--- a/include/drm/drm_clients.h
+++ b/include/drm/drm_clients.h
@@ -17,6 +17,8 @@ struct drm_pid_clients {
#if IS_ENABLED(CONFIG_CGROUP_DRM)
void drm_clients_close(struct drm_file *file_priv);
int drm_clients_open(struct drm_file *file_priv);
+
+void drm_clients_migrate(struct drm_file *file_priv);
#else
static inline void drm_clients_close(struct drm_file *file_priv)
{
@@ -26,6 +28,11 @@ static inline int drm_clients_open(struct drm_file *file_priv)
{
return 0;
}
+
+static inline void drm_clients_migrate(struct drm_file *file_priv)
+{
+
+}
#endif
unsigned int drm_pid_priority_levels(struct pid *pid, bool *non_uniform);
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index a4360e28e2db..2c1e356d3b73 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -280,6 +280,7 @@ struct drm_file {
#if IS_ENABLED(CONFIG_CGROUP_DRM)
struct list_head clink;
+ struct pid *cpid;
#endif
/**
--
2.34.1
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