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SubjectRe: [RFC PATCH v2 2/3] accel: add dedicated minor for accelerator devices
On Thu, Nov 3, 2022 at 7:26 AM Jiho Chu <jiho.chu@samsung.com> wrote:
>
> On Wed, 2 Nov 2022 22:34:04 +0200
> Oded Gabbay <ogabbay@kernel.org> wrote:
>
> > +/**
> > + * accel_open - open method for ACCEL file
> > + * @inode: device inode
> > + * @filp: file pointer.
> > + *
> > + * This function must be used by drivers as their &file_operations.open method.
> > + * It looks up the correct ACCEL device and instantiates all the per-file
> > + * resources for it. It also calls the &drm_driver.open driver callback.
> > + *
> > + * Return: 0 on success or negative errno value on failure.
> > + */
> > +int accel_open(struct inode *inode, struct file *filp)
> > +{
> > + struct drm_device *dev;
> > + struct drm_minor *minor;
> > + int retcode;
> > +
> > + minor = accel_minor_acquire(iminor(inode));
> > + if (IS_ERR(minor))
> > + return PTR_ERR(minor);
> > +
> > + dev = minor->dev;
> > +
> > + atomic_fetch_inc(&dev->open_count);
> > +
>
> Hi,
> It needs to consider drm_global_mutex to access open_count.
> please check doxy of open_count.
Now that I'm changing the code back to be part of drm.ko, I can return
all the code that is in drm_copy which I removed for this to compile.

>
>
> > + /* share address_space across all char-devs of a single device */
> > + filp->f_mapping = dev->anon_inode->i_mapping;
> > +
> > + retcode = drm_open_helper(filp, minor);
> > + if (retcode)
> > + goto err_undo;
> > +
> > + return 0;
> > +
> > +err_undo:
> > + atomic_dec(&dev->open_count);
> > + accel_minor_release(minor);
> > + return retcode;
> > +}
> > +EXPORT_SYMBOL_GPL(accel_open);
> > +
> > static int accel_stub_open(struct inode *inode, struct file *filp)
> > {
> > - DRM_DEBUG("Operation not supported");
> > + const struct file_operations *new_fops;
> > + struct drm_minor *minor;
> > + int err;
> > +
> > + DRM_DEBUG("\n");
>
> It seems useless.
Correct, I removed it in v3.
Thanks,
Oded
>
> Thanks.
> Jiho Chu

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