Messages in this thread | | | From | Alexandru Ardelean <> | Date | Fri, 20 Nov 2020 13:54:20 +0200 | Subject | Re: [Cocci] Proposal for a new checkpatch check; matching _set_drvdata() & _get_drvdata() |
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On Fri, Nov 20, 2020 at 12:47 PM Julia Lawall <julia.lawall@inria.fr> wrote: > > > > On Thu, 19 Nov 2020, Joe Perches wrote: > > > On Thu, 2020-11-19 at 17:16 +0200, Andy Shevchenko wrote: > > > On Thu, Nov 19, 2020 at 4:09 PM Alexandru Ardelean > > > <ardeleanalex@gmail.com> wrote: > > > > > > > > Hey, > > > > > > > > So, I stumbled on a new check that could be added to checkpatch. > > > > Since it's in Perl, I'm reluctant to try it. > > > > > > > > Seems many drivers got to a point where they now call (let's say) > > > > spi_set_drvdata(), but never access that information via > > > > spi_get_drvdata(). > > > > Reasons for this seem to be: > > > > 1. They got converted to device-managed functions and there is no > > > > longer a remove hook to require the _get_drvdata() access > > > > 2. They look like they were copied from a driver that had a > > > > _set_drvdata() and when the code got finalized, the _set_drvdata() was > > > > omitted > > > > > > > > There are a few false positives that I can notice at a quick look, > > > > like the data being set via some xxx_set_drvdata() and retrieved via a > > > > dev_get_drvdata(). > > > > > > I can say quite a few. And this makes a difference. > > > So, basically all drivers that are using PM callbacks would rather use > > > dev_get_drvdata() rather than bus specific. > > > > > > > I think checkpatch reporting these as well would be acceptable simply > > > > from a reviewability perspective. > > > > > > > > I did a shell script to quickly check these. See below. > > > > It's pretty badly written but it is enough for me to gather a list. > > > > And I wrote it in 5 minutes :P > > > > I initially noticed this in some IIO drivers, and then I suspected > > > > that this may be more widespread. > > > > > > It seems more suitable for coccinelle. > > > > To me as well. > > To me as well, since it seems to involve nonlocal information. > > I'm not sure to understand the original shell script. Is there > something interesting about pci_set_drvdata?
Ah, it's a stupid script I wrote in 5 minutes, so I did not bother to make things smart. In the text-matching I did in shell, there are some entries that come from comments and docs. It's only about 3-4 entries, so I just did a visual/manual ignore.
In essence: The script searches for all strings that contain _set_drvdata. The separators are whitespace. It creates a list of all xxxx_set_drvdata functions. For each xxxx_set_drvdata function: It checks all files that have a xxxx_set_drvdata entry, but no xxxx_get_drvdata
I piped this output into a file and started manually checking the drivers. There is one [I forget which function] that is xxxx_set_drvdata() but equivalent is xxxx_drvdata()
As Andy said, some precautions must be taken in places where xxxx_set_drvdata() is called but dev_get_drvdata() is used. Cases like PM suspend/resume calls. And there may be some cases outside this context.
> > julia
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