Messages in this thread Patch in this message | | | Date | Mon, 17 Feb 2020 09:18:04 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH] pinctrl: ingenic: Make unreachable path more robust |
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On Fri, Feb 14, 2020 at 11:37:04PM -0300, Paul Cercueil wrote: > > > I don't like the idea that you change this driver's code just to > > > work around > > > a bug in objtool, and I don't like the idea of working around a > > > future bug > > > that shouldn't be introduced in the first place. > > > > It's not an objtool bug. It's a byproduct of the fact that GCC's > > undefined behavior is inscrutable, and there's no way to determine that > > it actually *wants* to jump to a random function. > > > > And anyway, regardless of objtool, the patch is meant to make the code > > more robust. > > > > Do you not agree that BUG (defined behavior) is more robust than > > unreachable (undefined behavior)? > > It's a dead code path. That would be an undefined behaviour, if it was > taken, but it's not.
Given your confidence that humans don't introduce bugs, would you recommend that we
s/BUG()/unreachable()/
tree-wide?
Another option would be to remove the unreachable() statement, which would actually improve the generated code by making it more compact (16 bytes of i-cache savings), on top of removing the "fallthrough to next function" nastiness.
diff --git a/drivers/pinctrl/pinctrl-ingenic.c b/drivers/pinctrl/pinctrl-ingenic.c index 96f04d121ebd..13c7d3351ed5 100644 --- a/drivers/pinctrl/pinctrl-ingenic.c +++ b/drivers/pinctrl/pinctrl-ingenic.c @@ -2158,7 +2158,8 @@ static int ingenic_pinconf_set(struct pinctrl_dev *pctldev, unsigned int pin, break; default: - unreachable(); + /* unreachable */ + break; } }
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