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Wed, 16 Jul 2025 23:58:29 -0700 (PDT) Date: Thu, 17 Jul 2025 06:58:28 +0000 From: Wei Yang To: Andrew Morton Cc: wang lian , broonie@kernel.org, david@redhat.com, lorenzo.stoakes@oracle.com, sj@kernel.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, brauner@kernel.org, jannh@google.com, Liam.Howlett@oracle.com, shuah@kernel.org, vbabka@suse.cz, ludovico.zy.wu@gmail.com, gkwang@linx-info.com, p1ucky0923@gmail.com, ryncsn@gmail.com, zijing.zhang@proton.me Subject: Re: [PATCH] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" Message-ID: <20250717065828.cxnjfrl3iir5eb6y@master> Reply-To: Wei Yang References: <20250716123126.3851-1-lianux.mm@gmail.com> <20250716151543.998b121a58064011e9ce68cb@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250716151543.998b121a58064011e9ce68cb@linux-foundation.org> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 04905A0003 X-Stat-Signature: c47wf6f6sjdbxajcuwzp8c54iqmf6sog X-Rspam-User: X-HE-Tag: 1752735511-533807 X-HE-Meta: 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 k09eFNhR Gq0pAnz1Hq4IVOi/hioTtsNDBglVceMwAnQD9zdXZmyKyl/GOOXzgj3b2G1kBhqoAclbB++JXSkYqUHseJISqa2TEZEti1RiuL8P3qk6spTbvPvzMCPseI8Bgt9jQKWHfcCLr1KNTjTRVZ4jSgkegaXoEl495n/8rQZXOeG50xfCj197/NC98e8xuohvIF+/2ixZFDOU7pukQQIZH1I9ufFHs24yzGdAAO+sBdGq9NJTNdD91AdhLtAUBLkWv8T5Ewag+lWERMMNdWrl3hLZQ9BCySXzq+yexBuOPShO3Q1ujmKjoheJ/s10jd34MC+A8vnR1XESHyddYpt88dYzL31LSQV7HbvOQ32takI8KTsBqcwH9pwMH1xLvMPUSWPCki26C3JOa7w/IRVs5onG3lFe5Kohql1nH4upyeKthxm0XCmU68Wb55/Dq6oc62OYJil2vHD6kWK+QF9iucFOt2dHXfpG+nZHhgRahhRpWqaOQXENKaQAEspWbLSuKABFcugT3q/+XermgQ/65SsK0ozh2Tof6Ne4FJAf0a9s4ekj0OIJpXAQILCVhxnu0uicM2CpMYRm4LpXXAVxxxDswDTE+MTL8aM+Gpyk1YjloZvL3Z+Bd7qEdRWfuyxVpLr0isX8mNIZV1Q/5wNhRFrt49P6HduROQoIo2qIABHYpMIIUNjQyZ+tE+eXJSE6jdNuWuMXIYamjrNlQK2wKpOHa/RatqLyIpXA4dvFULKE/XcJarFIM/1mDP6QPVztkdXXN2DNgCG5NL8z8dnJ7ArzWflsbZlVG0ZtIXNvi3lC7HXP4Si8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 16, 2025 at 03:15:43PM -0700, Andrew Morton wrote: >On Wed, 16 Jul 2025 20:31:26 +0800 wang lian wrote: > >> Several mm selftests use the `asm volatile("" : "+r" (variable));` >> construct to force a read of a variable, preventing the compiler from >> optimizing away the memory access. This idiom is cryptic and duplicated >> across multiple test files. >> >> Following a suggestion from David[1], this patch refactors this >> common pattern into a FORCE_READ() macro >> >> tools/testing/selftests/mm/cow.c | 30 +++++++++---------- >> tools/testing/selftests/mm/hugetlb-madvise.c | 5 +--- >> tools/testing/selftests/mm/migration.c | 13 ++++---- >> tools/testing/selftests/mm/pagemap_ioctl.c | 4 +-- >> .../selftests/mm/split_huge_page_test.c | 4 +-- >> 5 files changed, 24 insertions(+), 32 deletions(-) > >The patch forgot to move the FORCE_READ definition into a header? > I get this after applying the patch. cow.c:1559:9: warning: implicit declaration of function ‘FORCE_READ’; did you mean ‘LOCK_READ’? [-Wimplicit-function-declaration] 1559 | FORCE_READ(mem); -- Wei Yang Help you, Help me