This was many times discussed by Russell King
and I also was about wrong usage of IS_ERR_OR_NULL()
in my patch. So I added this check and other people will
be at least warned about potentially wrong usage
of mentioned macro.
Quoting Russell:
| Well, the whole reasoning here is that IS_ERR_OR_NULL() is far too easy
| to get wrong - there are too many of this kind of crap in the kernel:
|
| foo = some_func();
| if (IS_ERR_OR_NULL(foo))
| return PTR_ERR(foo);
|
| which is wrong, because if foo _is_ NULL, the function doesn't return an
| error, it returns success instead. Of course, if some_func() never ever
| returns NULL in the first place, that can't happen, but then the additional
| test there for a NULL pointer is, to put it bluntly, total bollocks.
The full discussion may be found here:
http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874
Tested on:
+ if (IS_ERR_OR_NULL(soc_dev))
+ return PTR_ERR(soc_dev);
+
+ if (IS_ERR_OR_NULL(soc_dev))
+ return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;
The result is:
WARNING: Use of IS_ERR_OR_NULL is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874
+ if (IS_ERR_OR_NULL(soc_dev))
+ return PTR_ERR(soc_dev);
Signed-off-by: Ruslan Bilovol <[email protected]>
---
I'm not very experienced in the perl, so feel free to
comment this patch or fix it :)
scripts/checkpatch.pl | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index b954de5..6ec71bd 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3262,6 +3262,15 @@ sub process {
}
}
+# check for wrong "if (IS_ERR_OR_NULL(<foo>)) return PTR_ERR(<foo>)" uses
+ if ($prevline =~ /\bif\s*\(\s*IS_ERR_OR_NULL\s*\(\s*($Lval)\s*\)\s*\)/) {
+ my $expr = '\s*\(\s*' . quotemeta($1) . '\s*\)\s*;';
+ if ($line =~ /\b(\s*PTR_ERR)$expr/) {
+ WARN('IS_ERR_OR_NULL',
+ "Use of IS_ERR_OR_NULL is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874\n" . $hereprev);
+ }
+ }
+
# prefer usleep_range over udelay
if ($line =~ /\budelay\s*\(\s*(\d+)\s*\)/) {
# ignore udelay's < 10, however
--
1.7.9.5
On Tue, 2013-05-14 at 03:41 +0300, Ruslan Bilovol wrote:
> This was many times discussed by Russell King
> and I also was about wrong usage of IS_ERR_OR_NULL()
> in my patch. So I added this check and other people will
> be at least warned about potentially wrong usage
> of mentioned macro.
[]
> Tested on:
> + if (IS_ERR_OR_NULL(soc_dev))
> + return PTR_ERR(soc_dev);
> +
> + if (IS_ERR_OR_NULL(soc_dev))en
> + return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;
I did a grep for IS_ERR_OR_NULL and this misses variants like:
if (unlikely(IS_ERR_OR_NULL(etc...
Perhaps something like this?
---
scripts/checkpatch.pl | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index b954de5..18c7d8c 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2184,6 +2184,15 @@ sub process {
WARN("SUSPECT_CODE_INDENT",
"suspect code indent for conditional statements ($indent, $sindent)\n" . $herecurr . "$stat_real\n");
}
+
+# check for misuses of IS_ERR_OR_NULL
+ if ($stat =~ /^\+.*\bIS_ERR_OR_NULL\s*\(\s*($Lval)\s*\)/) {
+ my $test = $1;
+ if ($stat =~ /\bPTR_ERR\s*\(\s*${test}\s*\)/) {
+ WARN("IS_ERR_OR_NULL",
+ "Use of IS_ERR_OR_NULL($test) with PTR_ERR($test) is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874\n" . $herecurr . "$stat_real\n");
+ }
+ }
}
# Track the 'values' across context and added lines.
Hi Joe,
Thank you for looking into this.
On Tue, May 14, 2013 at 7:36 AM, Joe Perches <[email protected]> wrote:
> On Tue, 2013-05-14 at 03:41 +0300, Ruslan Bilovol wrote:
>> This was many times discussed by Russell King
>> and I also was about wrong usage of IS_ERR_OR_NULL()
>> in my patch. So I added this check and other people will
>> be at least warned about potentially wrong usage
>> of mentioned macro.
> []
>> Tested on:
>> + if (IS_ERR_OR_NULL(soc_dev))
>> + return PTR_ERR(soc_dev);
>> +
>> + if (IS_ERR_OR_NULL(soc_dev))en
>> + return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;
>
> I did a grep for IS_ERR_OR_NULL and this misses variants like:
>
> if (unlikely(IS_ERR_OR_NULL(etc...
Agree, I checked and you are right
>
> Perhaps something like this?
hmm.. your variant have false positives.
I used next 2 examples for verification:
This one - is incorrect usage of IS_ERR_OR_NULL
+ if (IS_ERR_OR_NULL(soc_dev))
+ return PTR_ERR(soc_dev);
But this one is correct and checkpach shouldn't react here but in your
version does react
+ if (IS_ERR_OR_NULL(soc_dev))
+ return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;
Care to fix it?
Best regards,
Ruslan
> ---
> scripts/checkpatch.pl | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index b954de5..18c7d8c 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2184,6 +2184,15 @@ sub process {
> WARN("SUSPECT_CODE_INDENT",
> "suspect code indent for conditional statements ($indent, $sindent)\n" . $herecurr . "$stat_real\n");
> }
> +
> +# check for misuses of IS_ERR_OR_NULL
> + if ($stat =~ /^\+.*\bIS_ERR_OR_NULL\s*\(\s*($Lval)\s*\)/) {
> + my $test = $1;
> + if ($stat =~ /\bPTR_ERR\s*\(\s*${test}\s*\)/) {
> + WARN("IS_ERR_OR_NULL",
> + "Use of IS_ERR_OR_NULL($test) with PTR_ERR($test) is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874\n" . $herecurr . "$stat_real\n");
> + }
> + }
> }
>
> # Track the 'values' across context and added lines.
>
>
> --
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