Re: [PATCH v2 07/11] drm/i915: Show i915_gem_context owner in debugfs

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On ma, 2016-05-23 at 12:34 +0100, Chris Wilson wrote:
> Print the context's owner (via the pid under file_priv) under debugfs.
> In doing so, we must be careful that the filp is not accessed after it
> is freed (notified via i915_gem_context_close).
> 
> v2: Mark the file_priv as closed.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c     | 17 +++++++++++++++--
>  drivers/gpu/drm/i915/i915_gem_context.c |  3 ++-
>  2 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index ae28e6e9d603..945fe4710b37 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2014,9 +2014,22 @@ static int i915_context_status(struct seq_file *m, void *unused)
>  			continue;
>  
>  		seq_printf(m, "HW context %u ", ctx->hw_id);
> +		if (IS_ERR(ctx->file_priv)) {
> +			seq_puts(m, "(deleted) ");
> +		} else if (ctx->file_priv) {
> +			struct pid *pid = ctx->file_priv->file->pid;
> +			struct task_struct *task;
> +
> +			task = get_pid_task(pid, PIDTYPE_PID);
> +			if (task) {
> +				seq_printf(m, "(%s [%d]) ",
> +					   task->comm, task->pid);
> +				put_task_struct(task);
> +			}
			
What if no task, should we display something still?

> +		} else
> +			seq_puts(m, "(kernel) ");
> +
>  		describe_ctx(m, ctx);
> -		if (ctx == dev_priv->kernel_context)
> -			seq_printf(m, "(kernel context) ");
>  
>  		if (i915.enable_execlists) {
>  			seq_putc(m, '\n');
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 474174c20be2..e552c936d262 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -468,6 +468,7 @@ static int context_idr_cleanup(int id, void *p, void *data)
>  {
>  	struct i915_gem_context *ctx = p;
>  
> +	ctx->file_priv = ERR_PTR(-EBADF);
>  	i915_gem_context_put(ctx);
>  	return 0;
>  }
> @@ -936,7 +937,7 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
>  		return PTR_ERR(ctx);
>  	}
>  
> -	idr_remove(&ctx->file_priv->context_idr, ctx->user_handle);
> +	idr_remove(&file_priv->context_idr, ctx->user_handle);
>  	i915_gem_context_put(ctx);
>  	mutex_unlock(&dev->struct_mutex);
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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