| Message ID | 20180709145612.4166409-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | gpio: aspeed: fix compile testing warning | expand |
On Monday, July 9, 2018, 4:56:03 PM CEST Arnd Bergmann wrote: > Gcc cannot always see that BUG_ON(1) is guaranteed to not > return, so we get a warning message in some configurations: > > drivers/gpio/gpio-aspeed.c: In function 'bank_reg': > drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void > function [-Werror=return-type] > > Using a plain BUG() is easier here and avoids the problem. > > Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpio/gpio-aspeed.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c > index 1e00f4045f9d..2342e154029b 100644 > --- a/drivers/gpio/gpio-aspeed.c > +++ b/drivers/gpio/gpio-aspeed.c > @@ -240,7 +240,7 @@ static inline void __iomem *bank_reg(struct aspeed_gpio > *gpio, case reg_cmdsrc1: > return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_1; > } > - BUG_ON(1); > + BUG(); > } > > #define GPIO_BANK(x) ((x) >> 5) Is the semantic of BUG() (and BUG_ON as well) to never return? If so, then just an idea: Is it possible to add some macro magic in BUG_ON(x) to fail compiling if x is compile-constant? Giving a hint the passed condition always fails, which indicates a problem, at least to me. From a short search I found this in drivers/gpu/vga/vgaarb.c L630-633: > if (vgadev_find(pdev) != NULL) { > BUG_ON(1); > goto fail; > } You can't fail with a BUG_ON(1) and try to do some error handling after that. Best regards, Alexander -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Jul 9, 2018 at 5:31 PM, Alexander Stein <alexander.stein@systec-electronic.com> wrote: > On Monday, July 9, 2018, 4:56:03 PM CEST Arnd Bergmann wrote: >> Gcc cannot always see that BUG_ON(1) is guaranteed to not >> return, so we get a warning message in some configurations: >> >> drivers/gpio/gpio-aspeed.c: In function 'bank_reg': >> drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void >> function [-Werror=return-type] >> >> Using a plain BUG() is easier here and avoids the problem. >> >> Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> --- >> drivers/gpio/gpio-aspeed.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c >> index 1e00f4045f9d..2342e154029b 100644 >> --- a/drivers/gpio/gpio-aspeed.c >> +++ b/drivers/gpio/gpio-aspeed.c >> @@ -240,7 +240,7 @@ static inline void __iomem *bank_reg(struct aspeed_gpio >> *gpio, case reg_cmdsrc1: >> return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_1; >> } >> - BUG_ON(1); >> + BUG(); >> } >> >> #define GPIO_BANK(x) ((x) >> 5) > > Is the semantic of BUG() (and BUG_ON as well) to never return? On most architectures and configurations yes, but not on some of the minor architectures if CONFIG_BUG is disabled. > If so, then > just an idea: Is it possible to add some macro magic in BUG_ON(x) to fail > compiling if x is compile-constant? Giving a hint the passed condition always > fails, which indicates a problem, at least to me. Not sure, that might not work well in cases where it's a compile-time constant in some configurations but variable in others. > From a short search I found this in drivers/gpu/vga/vgaarb.c L630-633: >> if (vgadev_find(pdev) != NULL) { >> BUG_ON(1); >> goto fail; >> } > You can't fail with a BUG_ON(1) and try to do some error handling after that. Right. Traditionally when CONFIG_BUG was disabled, we would have continued here, so that could have been intentional, but in any case a WARN_ON() would have been more appropriate here. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2018-07-09 at 16:56 +0200, Arnd Bergmann wrote: > Gcc cannot always see that BUG_ON(1) is guaranteed to not > return, so we get a warning message in some configurations: > > drivers/gpio/gpio-aspeed.c: In function 'bank_reg': > drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void function [-Werror=return-type] > > Using a plain BUG() is easier here and avoids the problem. > > Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Linus, can you plonk that on top of the patches in that topic branch you created ? > --- > drivers/gpio/gpio-aspeed.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c > index 1e00f4045f9d..2342e154029b 100644 > --- a/drivers/gpio/gpio-aspeed.c > +++ b/drivers/gpio/gpio-aspeed.c > @@ -240,7 +240,7 @@ static inline void __iomem *bank_reg(struct aspeed_gpio *gpio, > case reg_cmdsrc1: > return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_1; > } > - BUG_ON(1); > + BUG(); > } > > #define GPIO_BANK(x) ((x) >> 5) -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Jul 9, 2018 at 4:56 PM Arnd Bergmann <arnd@arndb.de> wrote: > Gcc cannot always see that BUG_ON(1) is guaranteed to not > return, so we get a warning message in some configurations: > > drivers/gpio/gpio-aspeed.c: In function 'bank_reg': > drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void function [-Werror=return-type] > > Using a plain BUG() is easier here and avoids the problem. > > Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Patch applied with Benjamin's ACK. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 10, 2018 at 1:53 AM Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote: > On Mon, 2018-07-09 at 16:56 +0200, Arnd Bergmann wrote: > > Gcc cannot always see that BUG_ON(1) is guaranteed to not > > return, so we get a warning message in some configurations: > > > > drivers/gpio/gpio-aspeed.c: In function 'bank_reg': > > drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void function [-Werror=return-type] > > > > Using a plain BUG() is easier here and avoids the problem. > > > > Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Linus, can you plonk that on top of the patches in that topic branch > you created ? I put it on top of my devel branch where I merged in the topic branch. As it's a fringe thing anyways I don't think we need to recreate the topic branch for this. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c index 1e00f4045f9d..2342e154029b 100644 --- a/drivers/gpio/gpio-aspeed.c +++ b/drivers/gpio/gpio-aspeed.c @@ -240,7 +240,7 @@ static inline void __iomem *bank_reg(struct aspeed_gpio *gpio, case reg_cmdsrc1: return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_1; } - BUG_ON(1); + BUG(); } #define GPIO_BANK(x) ((x) >> 5)
Gcc cannot always see that BUG_ON(1) is guaranteed to not return, so we get a warning message in some configurations: drivers/gpio/gpio-aspeed.c: In function 'bank_reg': drivers/gpio/gpio-aspeed.c:244:1: error: control reaches end of non-void function [-Werror=return-type] Using a plain BUG() is easier here and avoids the problem. Fixes: 44ddf559d579 ("gpio: aspeed: Rework register type accessors") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpio/gpio-aspeed.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)