On 3/24/20 2:35 PM, Chuhong Yuan wrote:
> On Fri, Mar 20, 2020 at 8:01 PM Bartlomiej Zolnierkiewicz
> <b.zolnierkie@xxxxxxxxxxx> wrote:
>>
>>
>> On 3/10/20 3:35 AM, Chuhong Yuan wrote:
>>> The driver forgets to free the I/O region in remove and probe
>>> failure.
>>> Add the missed calls to fix it.
>>>
>>> Signed-off-by: Chuhong Yuan <hslester96@xxxxxxxxx>
>>> ---
>>> Changes in v3:
>>> - Revise the commit message.
>>> - Add an error handler to suit the "goto error" before request_region().
>>> - Revise the order of operations in remove.
>>>
>>> drivers/video/fbdev/vesafb.c | 9 ++++++---
>>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c
>>> index a1fe24ea869b..c7bc9ace47d4 100644
>>> --- a/drivers/video/fbdev/vesafb.c
>>> +++ b/drivers/video/fbdev/vesafb.c
>>> @@ -439,7 +439,7 @@ static int vesafb_probe(struct platform_device *dev)
>>> "vesafb: abort, cannot ioremap video memory 0x%x @ 0x%lx\n",
>>> vesafb_fix.smem_len, vesafb_fix.smem_start);
>>> err = -EIO;
>>> - goto err;
>>> + goto err_release_region;
>>> }
>>>
>>> printk(KERN_INFO "vesafb: framebuffer at 0x%lx, mapped to 0x%p, "
>>> @@ -458,15 +458,17 @@ static int vesafb_probe(struct platform_device *dev)
>>>
>>> if (fb_alloc_cmap(&info->cmap, 256, 0) < 0) {
>>> err = -ENOMEM;
>>> - goto err;
>>> + goto err_release_region;
>>> }
>>> if (register_framebuffer(info)<0) {
>>> err = -EINVAL;
>>> fb_dealloc_cmap(&info->cmap);
>>> - goto err;
>>> + goto err_release_region;
>>> }
>>> fb_info(info, "%s frame buffer device\n", info->fix.id);
>>> return 0;
>>> +err_release_region:
>>> + release_region(0x3c0, 32);
>>
>> This is incorrect.
>>
>> The cleanup order should be the reverse of the probing order.
>>
>> Also request_region() return value is not checked by the driver
>> (there is a comment that it can fail and is optional):
>>
>> /* request failure does not faze us, as vgacon probably has this
>> * region already (FIXME) */
>> request_region(0x3c0, 32, "vesafb");
>>
>> so what would happen in such case? It seems that unconditionally
>> doing the release will result in freeing the I/O region owned by
>> the other driver (vgacon)..
>>
>
> Maybe we can add a field to represent whether the request succeeds?
> request_region() returns source *, we can store it and check whether
> it is null when
> we are going to call release_region().
Yes, this is a preferred approach.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
>>> err:
>>> arch_phys_wc_del(par->wc_cookie);
>>> if (info->screen_base)
>>> @@ -481,6 +483,7 @@ static int vesafb_remove(struct platform_device *pdev)
>>> struct fb_info *info = platform_get_drvdata(pdev);
>>>
>>> unregister_framebuffer(info);
>>> + release_region(0x3c0, 32);
>>> framebuffer_release(info);
>>>
>>> return 0;
>>>
>>
>> Best regards,
>> --
>> Bartlomiej Zolnierkiewicz
>> Samsung R&D Institute Poland
>> Samsung Electronics
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