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 <ruslan.bilo...@ti.com> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
