http://kernelnewbies.org/CheckpatchTips
The block about "Breaking function calls" is dubious.
The majority of code today uses arguments aligned to parenthesis.
The suggested 1 tab is in fact very infrequently used.
CodingStyle has this as "substantially to the right", not 1 tab.
btw: there's a perferred/preferred tyop too.
------------
Breaking function calls
Sometimes a call to a function has several variables, and you need to
break the line in the middle of those variables. Look at this example:
pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN, GFP_KERNEL, &pdata->urb->transfer_dma);
This line is too long, so we want to break it up. By default, vim will
increase the indentation of the trailing line by one tab:
pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
GFP_KERNEL, &pdata->urb->transfer_dma);
This style is fine, and generally perferred. However, some driver
writers prefer to have the trailing line of a function call line up with
the starting '('. They use tabs, followed by spaces, to align the
trailing line:
pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
GFP_KERNEL,
&pdata->urb->transfer_dma);
Again, the one tab indent style is preferred, but don't change lines
that use the other style.
>
> btw: there's a perferred/preferred tyop too.
>
Sorry, but I just couldn't ignore the irony of this. :P
-mandeep
Joe Perches <[email protected]> writes:
> This style is fine, and generally perferred. However, some driver
> writers prefer to have the trailing line of a function call line up with
> the starting '('. They use tabs, followed by spaces, to align the
> trailing line:
>
>
> pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
> GFP_KERNEL,
> &pdata->urb->transfer_dma);
It might be worth noting that the network subsystem maintainer prefers
this style as well. So most networking patches should probably use it.
The exception would be files which already use the other style.
You should also be aware of the implications of this style: You have to
modify all three lines if you change anything on the first line causing
the position of the starting '(' to change. I.e., a patch like this is
not acceptable:
-pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
+p->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
GFP_KERNEL,
&pdata->urb->transfer_dma);
It needs to be
-pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
- GFP_KERNEL,
- &pdata->urb->transfer_dma);
+p->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
+ GFP_KERNEL,
+ &pdata->urb->transfer_dma);
Bjørn