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Date:   Tue, 19 Apr 2022 13:17:24 -0700 (PDT)
Subject:     Re: arch/riscv/mm/init.c:782:83: warning: suggest braces around empty body in an 'if' statement
In-Reply-To: <202203280003.jGKBNwrv-lkp@intel.com>
CC:     kbuild-all@lists.01.org, linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmer@rivosinc.com>
To:     lkp@intel.com, panqinglin2020@iscas.ac.cn
Message-ID: <mhng-0a500fb4-ce93-4d52-bfda-2dc600286267@palmer-ri-x1c9>
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On Sun, 27 Mar 2022 09:05:03 PDT (-0700), lkp@intel.com wrote:
> Hi Qinglin,
>
> FYI, the error/warning still remains.

Thanks.  I'm not sure if I missed a patch for this, I can't find 
anything that looks relevant in my inbox.  I just sent one of my own to 
fix the issue, but if there's one I missed then happy to take that 
instead.

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   f022814633e1c600507b3a99691b4d624c2813f0
> commit: 677b9eb8810edc6c616a699018a83e24ed0cccab riscv: mm: Prepare pt_ops helper functions for sv57
> date:   6 weeks ago
> config: riscv-rv32_defconfig (https://download.01.org/0day-ci/archive/20220328/202203280003.jGKBNwrv-lkp@intel.com/config)
> compiler: riscv32-linux-gcc (GCC) 11.2.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=677b9eb8810edc6c616a699018a83e24ed0cccab
>         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>         git fetch --no-tags linus master
>         git checkout 677b9eb8810edc6c616a699018a83e24ed0cccab
>         # save the config file to linux build tree
>         mkdir build_dir
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/mm/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
>    arch/riscv/mm/init.c: In function 'create_fdt_early_page_table':
>>> arch/riscv/mm/init.c:782:83: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
>      782 |                                    (uintptr_t)early_dtb_pud, P4D_SIZE, PAGE_TABLE);
>          |                                                                                   ^
>    arch/riscv/mm/init.c:786:83: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
>      786 |                                    (uintptr_t)early_dtb_pmd, PUD_SIZE, PAGE_TABLE);
>          |                                                                                   ^
>    arch/riscv/mm/init.c: At top level:
>    arch/riscv/mm/init.c:813:13: warning: no previous prototype for 'pt_ops_set_early' [-Wmissing-prototypes]
>      813 | void __init pt_ops_set_early(void)
>          |             ^~~~~~~~~~~~~~~~
>    arch/riscv/mm/init.c:835:13: warning: no previous prototype for 'pt_ops_set_fixmap' [-Wmissing-prototypes]
>      835 | void __init pt_ops_set_fixmap(void)
>          |             ^~~~~~~~~~~~~~~~~
>    arch/riscv/mm/init.c:853:13: warning: no previous prototype for 'pt_ops_set_late' [-Wmissing-prototypes]
>      853 | void __init pt_ops_set_late(void)
>          |             ^~~~~~~~~~~~~~~
>
>
> vim +/if +782 arch/riscv/mm/init.c
>
>    764
>    765	/*
>    766	 * Setup a 4MB mapping that encompasses the device tree: for 64-bit kernel,
>    767	 * this means 2 PMD entries whereas for 32-bit kernel, this is only 1 PGDIR
>    768	 * entry.
>    769	 */
>    770	static void __init create_fdt_early_page_table(pgd_t *pgdir, uintptr_t dtb_pa)
>    771	{
>    772	#ifndef CONFIG_BUILTIN_DTB
>    773		uintptr_t pa = dtb_pa & ~(PMD_SIZE - 1);
>    774
>    775		create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA,
>    776				   IS_ENABLED(CONFIG_64BIT) ? early_dtb_pgd_next : pa,
>    777				   PGDIR_SIZE,
>    778				   IS_ENABLED(CONFIG_64BIT) ? PAGE_TABLE : PAGE_KERNEL);
>    779
>    780		if (pgtable_l5_enabled)
>    781			create_p4d_mapping(early_dtb_p4d, DTB_EARLY_BASE_VA,
>  > 782					   (uintptr_t)early_dtb_pud, P4D_SIZE, PAGE_TABLE);
>    783
>    784		if (pgtable_l4_enabled)
>    785			create_pud_mapping(early_dtb_pud, DTB_EARLY_BASE_VA,
>    786					   (uintptr_t)early_dtb_pmd, PUD_SIZE, PAGE_TABLE);
>    787
>    788		if (IS_ENABLED(CONFIG_64BIT)) {
>    789			create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
>    790					   pa, PMD_SIZE, PAGE_KERNEL);
>    791			create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA + PMD_SIZE,
>    792					   pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
>    793		}
>    794
>    795		dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
>    796	#else
>    797		/*
>    798		 * For 64-bit kernel, __va can't be used since it would return a linear
>    799		 * mapping address whereas dtb_early_va will be used before
>    800		 * setup_vm_final installs the linear mapping. For 32-bit kernel, as the
>    801		 * kernel is mapped in the linear mapping, that makes no difference.
>    802		 */
>    803		dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
>    804	#endif
>    805
>    806		dtb_early_pa = dtb_pa;
>    807	}
>    808