From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 593823AD51E; Tue, 26 May 2026 19:37:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779824259; cv=none; b=sq0rt4378mkvDmz7B9lcTTyOzoQ84qZ0S7Yz7O1AayLuc4QIaWrkrD1D4wd5ItiPxpdiR4hPzB2NS87v6qPrCrGAC5lOAD0gQEFAQWRB+r4Qu5nSmRgK/CnLScQtbLF3qWbBtcDiCx4ZhNLaPHB4xLC+h5fecAnBNyADcUzYON4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779824259; c=relaxed/simple; bh=eNdBcceAnV2lup2AYg86vhyp2UQb82XTEz4Muy5giV0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NCnMLDL8h8G4ME9CZKHCHjYevnmvtJMSaH//V6p4O/2bqz5dBkZXb9rw2dg9NU9I7ZzHFiN0lqS0eYlHsdUbsc6O1XJfXd8ALzWqW5wQxAmBvB8xFlgnDwOSe7mIaA6YVi9cYO2RzgutqgJVX4VrUyNHvWKeuCm1MU1oR21qQs8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l4aRlhv7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="l4aRlhv7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 660881F00A3D; Tue, 26 May 2026 19:37:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779824258; bh=PDbVz/BwnHRpIpjuYb7EvGBSPM9x9tSY/uMNXyuwFcw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=l4aRlhv79Ih0jQA12jftWmnDyxp0kC96VqsvMGsnrgJ7gkIJpjsMZ+PqqccvAelAf 3G3SdGTWTVum2hF+eYagcfnbBtRZRiLQJOv3yAmUbEyNhOGZwyCPMtGjZXNd9gYaJo Riov6LSv0UJg3wCZcH9fuqFEOrRLOlCNuC4bkpBaDfXOh4pzeYL+llx8ccWGvlE2Wf AQQZTdJDm0Qur+0+DSrkpban8al4u22Rj7R8UKeD1g9//wKVSEchjE5FN4W1vMjYib zwJvY39sCBHB9Tn8P8yLhcreq/ezwa7qa5V8daaz4wFuhggTM31kYhMI1D3vDjriha Q1V1hTM6cc8QA== Date: Tue, 26 May 2026 12:37:33 -0700 From: Nathan Chancellor To: Arnd Bergmann Cc: Andrew Morton , linux-kbuild@vger.kernel.org, Nicolas Schier , linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Arnd Bergmann , Bjorn Andersson , Andy Shevchenko , Christian Marangi , linux-kernel@vger.kernel.org Subject: Re: [PATCH] err.h: use __always_inline on all error pointer helpers Message-ID: <20260526193733.GC2851089@ax162> References: <20260526101851.2495110-1-arnd@kernel.org> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260526101851.2495110-1-arnd@kernel.org> On Tue, May 26, 2026 at 12:18:41PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann > > While testing randconfig builds on s390, I came across a > link failure with CONFIG_DMA_SHARED_BUFFER disabled: > > ERROR: modpost: "dma_buf_put" [drivers/iommu/iommufd/iommufd.ko] undefined! > > The problem here is that IS_ERR() is not inlined and dead code elimination > fails as a consequence. > > The err.h helpers all turn into a trivial assignment ot a bit mask > and should never result in a function call, so force them to always be > inline. This should generally result in better object code aside from > avoiding the link failure above. > > Signed-off-by: Arnd Bergmann Yeah, seems reasonable to me. I agree that this should generally result in better generated code as opposed to these helpers being generated out of line. Reviewed-by: Nathan Chancellor > --- > include/linux/err.h | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/include/linux/err.h b/include/linux/err.h > index 8c37be0620ab..d3e38d5b3a98 100644 > --- a/include/linux/err.h > +++ b/include/linux/err.h > @@ -36,7 +36,7 @@ > * > * Return: A pointer with @error encoded within its value. > */ > -static inline void * __must_check ERR_PTR(long error) > +static __always_inline void * __must_check ERR_PTR(long error) > { > return (void *) error; > } > @@ -60,7 +60,7 @@ static inline void * __must_check ERR_PTR(long error) > * @ptr: An error pointer. > * Return: The error code within @ptr. > */ > -static inline long __must_check PTR_ERR(__force const void *ptr) > +static __always_inline long __must_check PTR_ERR(__force const void *ptr) > { > return (long) ptr; > } > @@ -73,7 +73,7 @@ static inline long __must_check PTR_ERR(__force const void *ptr) > * @ptr: The pointer to check. > * Return: true if @ptr is an error pointer, false otherwise. > */ > -static inline bool __must_check IS_ERR(__force const void *ptr) > +static __always_inline bool __must_check IS_ERR(__force const void *ptr) > { > return IS_ERR_VALUE((unsigned long)ptr); > } > @@ -87,7 +87,7 @@ static inline bool __must_check IS_ERR(__force const void *ptr) > * > * Like IS_ERR(), but also returns true for a null pointer. > */ > -static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr) > +static __always_inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr) > { > return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr); > } > @@ -99,7 +99,7 @@ static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr) > * Explicitly cast an error-valued pointer to another pointer type in such a > * way as to make it clear that's what's going on. > */ > -static inline void * __musggt_check ERR_CAST(__force const void *ptr) > +static __always_inline void * __must_check ERR_CAST(__force const void *ptr) > { > /* cast away the const */ > return (void *) ptr; > @@ -122,7 +122,7 @@ static inline void * __must_check ERR_CAST(__force const void *ptr) > * > * Return: The error code within @ptr if it is an error pointer; 0 otherwise. > */ > -static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr) > +static __always_inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr) > { > if (IS_ERR(ptr)) > return PTR_ERR(ptr); > -- > 2.39.5 > -- Cheers, Nathan