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From: Tomas Winkler <tomasw@gmail.com>
Date: Tue, 19 Sep 2017 13:15:52 +0300
Message-ID: <CA+i0qc4EAn-ATk=3sSLdPd9=ZzjWFYr5b32nPkys_vrDdr5aUg@mail.gmail.com>
Subject: Re: [PATCH] staging: ion: create one device entry per heap
To: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
        driverdevel <devel@driverdev.osuosl.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Riley Andrews <riandrews@android.com>, Mark Brown <broonie@kernel.org>,
        Sumit Semwal <sumit.semwal@linaro.org>
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On Tue, Sep 19, 2017 at 1:07 PM, Benjamin Gaignard
<benjamin.gaignard@linaro.org> wrote:
> 2017-09-19 11:40 GMT+02:00 Dan Carpenter <dan.carpenter@oracle.com>:
>> On Mon, Sep 18, 2017 at 04:58:46PM +0200, Benjamin Gaignard wrote:
>>> -static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
>>> +static int validate_ioctl_arg(struct file *filp,
>>> +                           unsigned int cmd, union ion_ioctl_arg *arg)
>>>  {
>>>       int ret = 0;
>>> +     int mask = 1 << iminor(filp->f_inode);
>>>
>>>       switch (cmd) {
>>>       case ION_IOC_HEAP_QUERY:
>>> @@ -35,6 +37,9 @@ static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
>>>               ret |= arg->query.reserved1 != 0;
>>>               ret |= arg->query.reserved2 != 0;
>>>               break;
>>> +     case ION_IOC_ALLOC:
>>> +             ret = !(arg->allocation.heap_id_mask & mask);
>>
>>
>> validate_ioctl_arg() is really convoluted.  From reading just the patch
>> I at first thought we were returning 1 on failure.  Just say:
>>
>>         if (!(arg->allocation.heap_id_mask & mask))
>>                 return -EINVAL;
>>         return 0;
>>
>> If you want to fix the surrounding code in a separate patch that would
>> be good.  It would be more clear to say:
>>
>>                 if (arg->query.reserved0 != 0 ||
>>                     arg->query.reserved1 != 0 ||
>>                     arg->query.reserved2 != 0)
>>                         return -EINVAL;
>
> I agree I will add a fix for that in next version
>
>>
>>> +             break;
>>>       default:
>>>               break;
>>>       }
>>> @@ -70,7 +75,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>       if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
>>>               return -EFAULT;
>>>
>>> -     ret = validate_ioctl_arg(cmd, &data);
>>> +     ret = validate_ioctl_arg(filp, cmd, &data);
>>>       if (WARN_ON_ONCE(ret))
>>>               return ret;
>>>
>>> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
>>> index 93e2c90..5144f1a 100644
>>> --- a/drivers/staging/android/ion/ion.c
>>> +++ b/drivers/staging/android/ion/ion.c
>>> @@ -40,6 +40,8 @@
>>>
>>>  #include "ion.h"
>>>
>>> +#define ION_DEV_MAX 32
>>> +
>>>  static struct ion_device *internal_dev;
>>>  static int heap_id;
>>>
>>> @@ -541,11 +543,21 @@ void ion_device_add_heap(struct ion_heap *heap)
>>>  {
>>>       struct dentry *debug_file;
>>>       struct ion_device *dev = internal_dev;
>>> +     int ret;
>>>
>>>       if (!heap->ops->allocate || !heap->ops->free)
>>>               pr_err("%s: can not add heap with invalid ops struct.\n",
>>>                      __func__);
>>>
>>
>> I don't think it can happen in current code but we should proabably have
>> a check here for:
>>
>>         if (heap_id >= ION_DEV_MAX)
>>                 return -EBUSY;
>>
>> (It's possible I have missed something).
>>
>
> You are right I will add that
>
> Thanks
>>
>>> +     heap->ddev.devt = MKDEV(MAJOR(dev->devt), heap_id);
>>> +     dev_set_name(&heap->ddev, "ion%d", heap_id);
>>> +     device_initialize(&heap->ddev);
>>> +     cdev_init(&heap->chrdev, &ion_fops);
>>> +     heap->chrdev.owner = THIS_MODULE;
>>> +     ret = cdev_device_add(&heap->chrdev, &heap->ddev);
>>> +     if (ret < 0)
>>> +             return;
>>> +
>>>       spin_lock_init(&heap->free_lock);
>>>       heap->free_list_size = 0;

What will happen to an application which looks for /dev/ion?

Thanks
Tomas