Re: [PATCH 15/21] drm/i915/gt: Drop i915_address_space::file

[Jason Ekstrand <jason@jlekstrand.net>]

On Thu, Apr 29, 2021 at 7:37 AM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Fri, Apr 23, 2021 at 05:31:25PM -0500, Jason Ekstrand wrote:
> > There's a big comment saying how useful it is but no one is using this
> > for anything.
> >
> > Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
>
> I was trying to find anything before all your deletions, but alas nothing.
> I did spent a bit of time on this, and discovered that the debugfs use was
> nuked in
>
> db80a1294c23 ("drm/i915/gem: Remove per-client stats from debugfs/i915_gem_objects")
>
> After going through quite a few iterations, e.g.
>
> 5b5efdf79abf ("drm/i915: Make debugfs/per_file_stats scale better")
> f6e8aa387171 ("drm/i915: Report the number of closed vma held by each context in debugfs")
>
> The above removed the need for vm->file because stats debugfs file
> filtered using stats->vm instead of stats->file.
>
> History goes on until the original introduction of this (again for
> debugfs) in
>
> 2bfa996e031b ("drm/i915: Store owning file on the i915_address_space")

I've added the following to the commit message:

    It was added in 2bfa996e031b ("drm/i915: Store owning file on the
    i915_address_space") and used for debugfs at the time as well as telling
    the difference between the global GTT and a PPGTT.  In f6e8aa387171
    ("drm/i915: Report the number of closed vma held by each context in
    debugfs") we removed one use of it by switching to a context walk and
    comparing with the VM in the context.  Finally, VM stats for debugfs
    were entirely nuked in db80a1294c23 ("drm/i915/gem: Remove per-client
    stats from debugfs/i915_gem_objects")


> > ---
> >  drivers/gpu/drm/i915/gem/i915_gem_context.c |  9 ---------
> >  drivers/gpu/drm/i915/gt/intel_gtt.h         | 10 ----------
> >  drivers/gpu/drm/i915/selftests/mock_gtt.c   |  1 -
> >  3 files changed, 20 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > index 7929d5a8be449..db9153e0f85a7 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > @@ -921,17 +921,10 @@ static int gem_context_register(struct i915_gem_context *ctx,
> >                               u32 *id)
> >  {
> >       struct drm_i915_private *i915 = ctx->i915;
> > -     struct i915_address_space *vm;
> >       int ret;
> >
> >       ctx->file_priv = fpriv;
> >
> > -     mutex_lock(&ctx->mutex);
> > -     vm = i915_gem_context_vm(ctx);
> > -     if (vm)
> > -             WRITE_ONCE(vm->file, fpriv); /* XXX */
> > -     mutex_unlock(&ctx->mutex);
> > -
> >       ctx->pid = get_task_pid(current, PIDTYPE_PID);
> >       snprintf(ctx->name, sizeof(ctx->name), "%s[%d]",
> >                current->comm, pid_nr(ctx->pid));
> > @@ -1030,8 +1023,6 @@ int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
> >       if (IS_ERR(ppgtt))
> >               return PTR_ERR(ppgtt);
> >
> > -     ppgtt->vm.file = file_priv;
> > -
> >       if (args->extensions) {
> >               err = i915_user_extensions(u64_to_user_ptr(args->extensions),
> >                                          NULL, 0,
> > diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
> > index e67e34e179131..4c46068e63c9d 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
> > @@ -217,16 +217,6 @@ struct i915_address_space {
>
> Pls also delete the drm_i915_file_private pre-dcl in this file.

Done!

> With this added and the history adequately covered in the commit message:
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Thanks

--Jason


>
> >       struct intel_gt *gt;
> >       struct drm_i915_private *i915;
> >       struct device *dma;
> > -     /*
> > -      * Every address space belongs to a struct file - except for the global
> > -      * GTT that is owned by the driver (and so @file is set to NULL). In
> > -      * principle, no information should leak from one context to another
> > -      * (or between files/processes etc) unless explicitly shared by the
> > -      * owner. Tracking the owner is important in order to free up per-file
> > -      * objects along with the file, to aide resource tracking, and to
> > -      * assign blame.
> > -      */
> > -     struct drm_i915_file_private *file;
> >       u64 total;              /* size addr space maps (ex. 2GB for ggtt) */
> >       u64 reserved;           /* size addr space reserved */
> >
> > diff --git a/drivers/gpu/drm/i915/selftests/mock_gtt.c b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> > index 5c7ae40bba634..cc047ec594f93 100644
> > --- a/drivers/gpu/drm/i915/selftests/mock_gtt.c
> > +++ b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> > @@ -73,7 +73,6 @@ struct i915_ppgtt *mock_ppgtt(struct drm_i915_private *i915, const char *name)
> >       ppgtt->vm.gt = &i915->gt;
> >       ppgtt->vm.i915 = i915;
> >       ppgtt->vm.total = round_down(U64_MAX, PAGE_SIZE);
> > -     ppgtt->vm.file = ERR_PTR(-ENODEV);
> >       ppgtt->vm.dma = i915->drm.dev;
> >
> >       i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
> > --
> > 2.31.1
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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