Hi,
On 08/22/2012 05:05 PM, Alan Stern wrote:
> On Wed, 22 Aug 2012, Hans de Goede wrote:
>
>> Apps which deal with devices which also have a kernel driver, need to do
>> the following:
>> 1) Check which driver is attached, so as to not detach the wrong driver
>> (ie detaching usbfs while another instance of the app is using the
>> device)
>> 2) Detach the kernel driver
>> 3) Claim the interface
>>
>> Where moving from one step to the next for both 1-2 and 2-3 consists of
>> a (small) race window. So currently such apps are racy and people just live
>> with it.
>>
>> This patch adds a new ioctl which makes it possible for apps to do this
>> in a race free manner. For flexibility apps can choose to:
>> 1) Specify the driver to disconnect
>> 2) Specify to disconnect any driver except for the one named by the app
>> 3) Disconnect any driver
>>
>> Note that if there is no driver attached, the ioctl will just act like the
>> regular claim-interface ioctl, this is by design, as returning an error for
>> this condition would open a new bag of race-conditions.
>
> ...
>
>> + if ((dc.flags & USBDEVFS_DISCONNECT_CLAIM_IF_DRIVER) &&
>> + strncmp(dc.driver, intf->dev.driver->name,
>> + sizeof(dc.driver)) != 0)
>> + return -EBUSY;
>> +
>> + if ((dc.flags & USBDEVFS_DISCONNECT_CLAIM_EXCEPT_DRIVER) &&
>> + strncmp(dc.driver, intf->dev.driver->name,
>> + sizeof(dc.driver)) == 0)
>> + return -EBUSY;
>
> Please don't indent continuation lines by exactly one tab stop. It
> makes them look like the start of a sub-block.
Ok, so you want 4 spaces there to but the 's' of strncmp below the second
'(' I assume? I actually had that first, then changed to this :)
Before I respin the patch, any other remarks from you?
Regards,
Hams
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