Re: [PATCH RESEND drm-misc 4/4] dma-buf: heaps: make dma_heap_class constant

From: Sumit Semwal <sumit.semwal@linaro.org>
To: "T.J. Mercier" <tjmercier@google.com>
Cc: "Ricardo B. Marliere" <ricardo@marliere.net>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"David Airlie" <airlied@gmail.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Helge Deller" <deller@gmx.de>,
	"Benjamin Gaignard" <benjamin.gaignard@collabora.com>,
	"Brian Starkey" <Brian.Starkey@arm.com>,
	"John Stultz" <jstultz@google.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-fbdev@vger.kernel.org, linux-media@vger.kernel.org,
	linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH RESEND drm-misc 4/4] dma-buf: heaps: make dma_heap_class constant
Date: Thu, 7 Mar 2024 13:07:15 +0530	[thread overview]
Message-ID: <CAO_48GH_RyeTkUsZ9Ad=o2D+Poh3DVQnXiOmyApuWy2Ycn5P5w@mail.gmail.com> (raw)
In-Reply-To: <CABdmKX0VGyBdTo8gzEocyz2HFcqEtu_31PYVjWzioBdCbnXW6w@mail.gmail.com>

Hello Ricardo,

On Tue, 5 Mar 2024 at 22:37, T.J. Mercier <tjmercier@google.com> wrote:
>
> On Tue, Mar 5, 2024 at 3:34 AM Ricardo B. Marliere <ricardo@marliere.net> wrote:
> >
> > Since commit 43a7206b0963 ("driver core: class: make class_register() take
> > a const *"), the driver core allows for struct class to be in read-only
> > memory, so move the dma_heap_class structure to be declared at build time
> > placing it into read-only memory, instead of having to be dynamically
> > allocated at boot time.
> >
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
> > ---
> >  drivers/dma-buf/dma-heap.c | 26 ++++++++++++++------------
> >  1 file changed, 14 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
> > index 84ae708fafe7..bcca6a2bbce8 100644
> > --- a/drivers/dma-buf/dma-heap.c
> > +++ b/drivers/dma-buf/dma-heap.c
> > @@ -43,10 +43,18 @@ struct dma_heap {
> >         struct cdev heap_cdev;
> >  };
> >
> > +static char *dma_heap_devnode(const struct device *dev, umode_t *mode)
> > +{
> > +       return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
> > +}
> > +
> >  static LIST_HEAD(heap_list);
> >  static DEFINE_MUTEX(heap_list_lock);
> >  static dev_t dma_heap_devt;
> > -static struct class *dma_heap_class;
> > +static struct class dma_heap_class = {
> > +       .name = DEVNAME,
> > +       .devnode = dma_heap_devnode,
> > +};
> >  static DEFINE_XARRAY_ALLOC(dma_heap_minors);
> >
> >  static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
> > @@ -261,7 +269,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
> >                 goto err1;
> >         }
> >
> > -       dev_ret = device_create(dma_heap_class,
> > +       dev_ret = device_create(&dma_heap_class,
> >                                 NULL,
> >                                 heap->heap_devt,
> >                                 NULL,
> > @@ -291,7 +299,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
> >         return heap;
> >
> >  err3:
> > -       device_destroy(dma_heap_class, heap->heap_devt);
> > +       device_destroy(&dma_heap_class, heap->heap_devt);
> >  err2:
> >         cdev_del(&heap->heap_cdev);
> >  err1:
> > @@ -301,11 +309,6 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
> >         return err_ret;
> >  }
> >
> > -static char *dma_heap_devnode(const struct device *dev, umode_t *mode)
> > -{
> > -       return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
> > -}
> > -
> >  static int dma_heap_init(void)
> >  {
> >         int ret;
> > @@ -314,12 +317,11 @@ static int dma_heap_init(void)
> >         if (ret)
> >                 return ret;
> >
> > -       dma_heap_class = class_create(DEVNAME);
> > -       if (IS_ERR(dma_heap_class)) {
> > +       ret = class_register(&dma_heap_class);
> > +       if (ret) {
> >                 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
> > -               return PTR_ERR(dma_heap_class);
> > +               return ret;
> >         }
> > -       dma_heap_class->devnode = dma_heap_devnode;
> >
> >         return 0;
> >  }
> >
> > --
> > 2.43.0
>
> Reviewed-by: T.J. Mercier <tjmercier@google.com>

FWIW, please free to add my
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>

>
>
> Is this really a resend? I don't see anything on lore and I can't
> recall seeing this patch in my inbox before.

Best,
Sumit.

-- 
Thanks and regards,

Sumit Semwal (he / him)
Tech Lead - LCG, Vertical Technologies
Linaro.org │ Open source software for ARM SoCs