linux-kernel - Re: [PATCH 30/30] Staging: comedi: fix printk issue in jr3

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Date:	Wed, 14 Dec 2011 21:25:17 -0500
From:	Valdis.Kletnieks@...edu
To:	Ravishankar karkala Mallikarjunayya 
	<ravishankar.km@...enturtles.in>
Cc:	gregkh@...e.de, wfp5p@...ginia.edu, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 30/30] Staging: comedi: fix printk issue in jr3_pci.c

On Mon, 12 Dec 2011 12:52:19 +0530, Ravishankar karkala Mallikarjunayya said:
> This is a patch to the jr3_pci.c file that fixes up a
> printk warning found by the checkpatch.pl tool.

> diff --git a/drivers/staging/comedi/drivers/jr3_pci.c b/drivers/staging/comedi/drivers/jr3_pci.c
> index 2a97894..6a79ba1 100644
> --- a/drivers/staging/comedi/drivers/jr3_pci.c
> +++ b/drivers/staging/comedi/drivers/jr3_pci.c
> @@ -593,24 +593,24 @@ static struct poll_delay_t jr3_pci_poll_subdevice(struct comedi_subdevice *s)
>  					min_full_scale =
>  					    get_min_full_scales(channel);
>  					printk("Obtained Min. Full Scales:\n");
> -					printk("%i   ", (min_full_scale).fx);
> -					printk("%i   ", (min_full_scale).fy);
> -					printk("%i   ", (min_full_scale).fz);
> -					printk("%i   ", (min_full_scale).mx);
> -					printk("%i   ", (min_full_scale).my);
> -					printk("%i   ", (min_full_scale).mz);
> -					printk("\n");
> +					printk(KERN_DEBUG "%i ", (min_full_scale).fx);
> +					printk(KERN_CONT "%i ", (min_full_scale).fy);
> +					printk(KERN_CONT "%i ", (min_full_scale).fz);
> +					printk(KERN_CONT "%i ", (min_full_scale).mx);
> +					printk(KERN_CONT "%i ", (min_full_scale).my);
> +					printk(KERN_CONT "%i ", (min_full_scale).mz);
> +					printk(KERN_CONT "\n");

Is there a reason that as long as you were fixing this code, you didn't make it
one call to printk?

					printk(KERN_DEBUG,"%i %i %i %i %i %i\n",
						(min_full_scale).fx),
						(min_full_scale).fy),
						(min_full_scale).fz),
						(min_full_scale).mx),
						(min_full_scale).my),
						(min_full_scale).mz));

Doing it this way helps guarantee that another CPU doesn't inject a printk into
the middle and split up your output.

Also, there should be at least a *short* text string in that printk saying what
it is.  printk(KERN_DEBUG,"jr3_poll %i"   or similar would be a start.
Otherwise you get a line with 6 integers in it.

Also, if you're indented that far to the right, that driver is probably in
serious need of some restructuring or refactoring.


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