Messages in this thread | | | From | Arnd Bergmann <> | Date | Mon, 17 Jul 2017 16:26:23 +0200 | Subject | Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result interpreted as bool |
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On Mon, Jul 17, 2017 at 3:45 PM, Hans Verkuil <hverkuil@xs4all.nl> wrote: > On 14/07/17 11:36, Arnd Bergmann wrote: >> @@ -201,8 +202,9 @@ static int cx18_g_fmt_sliced_vbi_cap(struct file *file, void *fh, >> * digitizer/slicer. Note, cx18_av_vbi() wipes the passed in >> * fmt->fmt.sliced under valid calling conditions >> */ >> - if (v4l2_subdev_call(cx->sd_av, vbi, g_sliced_fmt, &fmt->fmt.sliced)) >> - return -EINVAL; >> + ret = v4l2_subdev_call(cx->sd_av, vbi, g_sliced_fmt, &fmt->fmt.sliced); >> + if (ret) >> + return ret; > > Please keep the -EINVAL here. I can't be 100% certain that returning 'ret' wouldn't > break something.
I think Dan was recommending the opposite here, if I understood you both correctly: he said we should propagate the error code unless we know it's wrong, while you want to keep the current behavior to avoid introducing changes ;-)
I guess in either case, looking at the callers more carefully would be a good idea.
>> - return 0; >> + return ret; >> } >> >> int atomisp_flash_enable(struct atomisp_sub_device *asd, int num_frames) >> > > This is all very hackish, though. I'm not terribly keen on this patch. It's not > clear to me *why* these warnings appear in your setup.
it's possible that this only happened with 'ccache', which first preprocesses the source and the passes it with v4l2_subdev_call expanded into the compiler. This means the line looks like
if ((!(cx->sd_av) ? -ENODEV : (((cx->sd_av)->ops->vbi && (cx->sd_av)->ops->vbi->g_sliced_fmt) ? (cx->sd_av)->ops->vbi->g_sliced_fmt(cx->sd_av)), &fmt->fmt.sliced) : -ENOIOCTLCMD))
The compiler now complains about the sub-expression that it sees for cx->sd_av==NULL:
if (-ENODEV)
which it considers nonsense because it is always true and the value gets ignored.
Let me try again without ccache for now and see what warnings remain. We can find a solution for those first, and then decide how to deal with ccache.
Arnd
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