[Intel-gfx] [RFC 2/8] drm/i915: Update client name on context create

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-01-10 13:30:43)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Some clients have the DRM fd passed to them over a socket by the X server.
> 
> Grab the real client and pid when they create their first context and
> update the exposed data for more useful enumeration.
> 
> v2:
>  * Do not leak the pid reference and borrow context idr_lock. (Chris)
> 
> v3:
>  * More avoiding leaks. (Chris)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_context.c | 36 ++++++++++++++++++---
>  drivers/gpu/drm/i915/i915_drm_client.c      |  4 +--
>  drivers/gpu/drm/i915/i915_drm_client.h      |  4 +++
>  3 files changed, 37 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index a2e57e62af30..ba3c29a01535 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -77,6 +77,7 @@
>  #include "gt/intel_lrc_reg.h"
>  #include "gt/intel_ring.h"
>  
> +#include "i915_drm_client.h"
>  #include "i915_gem_context.h"
>  #include "i915_globals.h"
>  #include "i915_trace.h"
> @@ -2181,7 +2182,10 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
>  {
>         struct drm_i915_private *i915 = to_i915(dev);
>         struct drm_i915_gem_context_create_ext *args = data;
> +       struct drm_i915_file_private *file_priv = file->driver_priv;
> +       struct i915_drm_client *client = file_priv->client;
>         struct create_ext ext_data;
> +       struct pid *pid;
>         int ret;
>         u32 id;
>  
> @@ -2195,16 +2199,35 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
>         if (ret)
>                 return ret;
>  
> -       ext_data.fpriv = file->driver_priv;
> +       pid = get_task_pid(current, PIDTYPE_PID);
> +
> +       ext_data.fpriv = file_priv;

Might as well do this in the declaration ?

struct create_ext ext_data {
	.fpriv = file->driver_priv,
};
struct i915_drm_client *client = ext_data.fpriv->client;

?

>         if (client_is_banned(ext_data.fpriv)) {
>                 DRM_DEBUG("client %s[%d] banned from creating ctx\n",
> -                         current->comm, task_pid_nr(current));
> -               return -EIO;
> +                         current->comm, pid_nr(pid));
> +               ret = -EIO;
> +               goto err_pid;
> +       }
> +
> +       /*
> +        * Borrow struct_mutex to protect the client remove-add cycle.
> +        */
> +       ret = mutex_lock_interruptible(&dev->struct_mutex);
> +       if (ret)
> +               goto err_pid;
> +       if (client->pid != pid) {
> +               __i915_drm_client_unregister(client);
> +               ret = __i915_drm_client_register(client, current);
>         }
> +       mutex_unlock(&dev->struct_mutex);
> +       if (ret)
> +               goto err_pid;

-> i915_drm_client_update();

And let it manage the pid locally?

>  
>         ext_data.ctx = i915_gem_create_context(i915, args->flags);
> -       if (IS_ERR(ext_data.ctx))
> -               return PTR_ERR(ext_data.ctx);
> +       if (IS_ERR(ext_data.ctx)) {
> +               ret = PTR_ERR(ext_data.ctx);
> +               goto err_pid;
> +       }
>  
>         if (args->flags & I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS) {
>                 ret = i915_user_extensions(u64_to_user_ptr(args->extensions),
> @@ -2226,6 +2249,9 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
>  
>  err_ctx:
>         context_close(ext_data.ctx);
> +err_pid:
> +       put_pid(pid);
> +
>         return ret;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/i915_drm_client.c b/drivers/gpu/drm/i915/i915_drm_client.c
> index 02356f48d85b..666ec67c77e9 100644
> --- a/drivers/gpu/drm/i915/i915_drm_client.c
> +++ b/drivers/gpu/drm/i915/i915_drm_client.c
> @@ -36,7 +36,7 @@ show_client_pid(struct device *kdev, struct device_attribute *attr, char *buf)
>                         client->closed ? ">" : "");
>  }
>  
> -static int
> +int
>  __i915_drm_client_register(struct i915_drm_client *client,
>                            struct task_struct *task)
>  {
> @@ -89,7 +89,7 @@ __i915_drm_client_register(struct i915_drm_client *client,
>         return ret;
>  }
>  
> -static void __i915_drm_client_unregister(struct i915_drm_client *client)
> +void __i915_drm_client_unregister(struct i915_drm_client *client)
>  {
>         if (!client->name)
>                 return; /* fbdev client or error during drm open */
> diff --git a/drivers/gpu/drm/i915/i915_drm_client.h b/drivers/gpu/drm/i915/i915_drm_client.h
> index 8b261dc4a1f3..2c692345bc4e 100644
> --- a/drivers/gpu/drm/i915/i915_drm_client.h
> +++ b/drivers/gpu/drm/i915/i915_drm_client.h
> @@ -58,4 +58,8 @@ void i915_drm_client_close(struct i915_drm_client *client);
>  struct i915_drm_client *i915_drm_client_add(struct i915_drm_clients *clients,
>                                             struct task_struct *task);
>  
> +int __i915_drm_client_register(struct i915_drm_client *client,
> +                              struct task_struct *task);
> +void __i915_drm_client_unregister(struct i915_drm_client *client);
> +
>  #endif /* !__I915_DRM_CLIENT_H__ */
> -- 
> 2.20.1
> 
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