Re: [RFC 2/3] drm/msm: Rework get_comm_cmdline() helper

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Apr 18, 2023 at 09:27:49AM +0100, Tvrtko Ursulin wrote:
> 
> On 17/04/2023 21:12, Rob Clark wrote:
> > From: Rob Clark <robdclark@chromium.org>
> > 
> > Make it work in terms of ctx so that it can be re-used for fdinfo.
> > 
> > Signed-off-by: Rob Clark <robdclark@chromium.org>
> > ---
> >   drivers/gpu/drm/msm/adreno/adreno_gpu.c |  4 ++--
> >   drivers/gpu/drm/msm/msm_drv.c           |  2 ++
> >   drivers/gpu/drm/msm/msm_gpu.c           | 13 ++++++-------
> >   drivers/gpu/drm/msm/msm_gpu.h           | 12 ++++++++++--
> >   drivers/gpu/drm/msm/msm_submitqueue.c   |  1 +
> >   5 files changed, 21 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > index bb38e728864d..43c4e1fea83f 100644
> > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > @@ -412,7 +412,7 @@ int adreno_set_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
> >   		/* Ensure string is null terminated: */
> >   		str[len] = '\0';
> > -		mutex_lock(&gpu->lock);
> > +		mutex_lock(&ctx->lock);
> >   		if (param == MSM_PARAM_COMM) {
> >   			paramp = &ctx->comm;
> > @@ -423,7 +423,7 @@ int adreno_set_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
> >   		kfree(*paramp);
> >   		*paramp = str;
> > -		mutex_unlock(&gpu->lock);
> > +		mutex_unlock(&ctx->lock);
> >   		return 0;
> >   	}
> > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > index 3d73b98d6a9c..ca0e89e46e13 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.c
> > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > @@ -581,6 +581,8 @@ static int context_init(struct drm_device *dev, struct drm_file *file)
> >   	rwlock_init(&ctx->queuelock);
> >   	kref_init(&ctx->ref);
> > +	ctx->pid = get_pid(task_pid(current));
> 
> Would it simplify things for msm if DRM core had an up to date file->pid as
> proposed in
> https://patchwork.freedesktop.org/patch/526752/?series=109902&rev=4 ? It
> gets updated if ioctl issuer is different than fd opener and this being
> context_init here reminded me of it. Maybe you wouldn't have to track the
> pid in msm?

Can we go one step further and let the drm fdinfo stuff print these new
additions? Consistency across drivers and all that.

Also for a generic trigger I think any driver ioctl is good enough (we
only really need to avoid the auth dance when you're not on a render
node).
-Daniel

> 
> Regards,
> 
> Tvrtko
> 
> > +	mutex_init(&ctx->lock);
> >   	msm_submitqueue_init(dev, ctx);
> >   	ctx->aspace = msm_gpu_create_private_address_space(priv->gpu, current);
> > diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> > index c403912d13ab..f0f4f845c32d 100644
> > --- a/drivers/gpu/drm/msm/msm_gpu.c
> > +++ b/drivers/gpu/drm/msm/msm_gpu.c
> > @@ -327,18 +327,17 @@ find_submit(struct msm_ringbuffer *ring, uint32_t fence)
> >   static void retire_submits(struct msm_gpu *gpu);
> > -static void get_comm_cmdline(struct msm_gem_submit *submit, char **comm, char **cmd)
> > +static void get_comm_cmdline(struct msm_file_private *ctx, char **comm, char **cmd)
> >   {
> > -	struct msm_file_private *ctx = submit->queue->ctx;
> >   	struct task_struct *task;
> > -	WARN_ON(!mutex_is_locked(&submit->gpu->lock));
> > -
> >   	/* Note that kstrdup will return NULL if argument is NULL: */
> > +	mutex_lock(&ctx->lock);
> >   	*comm = kstrdup(ctx->comm, GFP_KERNEL);
> >   	*cmd  = kstrdup(ctx->cmdline, GFP_KERNEL);
> > +	mutex_unlock(&ctx->lock);
> > -	task = get_pid_task(submit->pid, PIDTYPE_PID);
> > +	task = get_pid_task(ctx->pid, PIDTYPE_PID);
> >   	if (!task)
> >   		return;
> > @@ -372,7 +371,7 @@ static void recover_worker(struct kthread_work *work)
> >   		if (submit->aspace)
> >   			submit->aspace->faults++;
> > -		get_comm_cmdline(submit, &comm, &cmd);
> > +		get_comm_cmdline(submit->queue->ctx, &comm, &cmd);
> >   		if (comm && cmd) {
> >   			DRM_DEV_ERROR(dev->dev, "%s: offending task: %s (%s)\n",
> > @@ -460,7 +459,7 @@ static void fault_worker(struct kthread_work *work)
> >   		goto resume_smmu;
> >   	if (submit) {
> > -		get_comm_cmdline(submit, &comm, &cmd);
> > +		get_comm_cmdline(submit->queue->ctx, &comm, &cmd);
> >   		/*
> >   		 * When we get GPU iova faults, we can get 1000s of them,
> > diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> > index 7a4fa1b8655b..b2023a42116b 100644
> > --- a/drivers/gpu/drm/msm/msm_gpu.h
> > +++ b/drivers/gpu/drm/msm/msm_gpu.h
> > @@ -377,17 +377,25 @@ struct msm_file_private {
> >   	 */
> >   	int sysprof;
> > +	/** @pid: Process that opened this file. */
> > +	struct pid *pid;
> > +
> > +	/**
> > +	 * lock: Protects comm and cmdline
> > +	 */
> > +	struct mutex lock;
> > +
> >   	/**
> >   	 * comm: Overridden task comm, see MSM_PARAM_COMM
> >   	 *
> > -	 * Accessed under msm_gpu::lock
> > +	 * Accessed under msm_file_private::lock
> >   	 */
> >   	char *comm;
> >   	/**
> >   	 * cmdline: Overridden task cmdline, see MSM_PARAM_CMDLINE
> >   	 *
> > -	 * Accessed under msm_gpu::lock
> > +	 * Accessed under msm_file_private::lock
> >   	 */
> >   	char *cmdline;
> > diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
> > index 0e803125a325..0444ba04fa06 100644
> > --- a/drivers/gpu/drm/msm/msm_submitqueue.c
> > +++ b/drivers/gpu/drm/msm/msm_submitqueue.c
> > @@ -61,6 +61,7 @@ void __msm_file_private_destroy(struct kref *kref)
> >   	}
> >   	msm_gem_address_space_put(ctx->aspace);
> > +	put_pid(ctx->pid);
> >   	kfree(ctx->comm);
> >   	kfree(ctx->cmdline);
> >   	kfree(ctx);

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch