On 28/12/11 14:46, Shashidhar Hiremath wrote:
> On Wed, Dec 28, 2011 at 5:39 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>> On 28/12/11 12:46, Shashidhar hiremath wrote:
>>> From: Shashidhar Hiremath <shashidharh@xxxxxxxxxxxxxxx>
>>>
>>> The Patch adds a check to disable the IOCTL from running when the card is mounted
>>> or device is opened elsewhere.
>>
>> What if someone wants to do that.
> The issue with not having this is that if there is huge size data
> transfer operation happening, the IOCTL issuing will corrupt the data
> transfer operation. So it would be better to finish the device's
> access by one thing and give control to ioctl after that.
It does claim the host so the ioctl will wait while I/O requests
are being processed.
>>
>> Generally the kernel does not prevent access to raw block devices
>> just because a file system is mounted on them, so I guess MMC should
>> not either.
>
>>
>>
>>>
>>> Signed-off-by: Shashidhar Hiremath <shashidharh@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/mmc/card/block.c | 6 ++++++
>>> 1 files changed, 6 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>>> index 0cad48a..e680929 100644
>>> --- a/drivers/mmc/card/block.c
>>> +++ b/drivers/mmc/card/block.c
>>> @@ -387,6 +387,12 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>> err = -EINVAL;
>>> goto cmd_done;
>>> }
>>> + /* Disallow the IOCTL run if card is already mounted or device is
>>> + * opened elsewhere */
>>> + if (md->usage > 3) {
>>> + err = -EINVAL;
>>> + goto cmd_done;
>>> + }
>>
>> Checking the usage will not work consistently e.g.
>> if there is a sysfs access or another ioctl access at the
>> same time, or just some other kernel user of the device.
>>
>>>
>>> card = md->queue.card;
>>> if (IS_ERR(card)) {
>>
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>
>
>
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