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AJvYcCW+79M5vbSY/EZfoMvp2eJwozcfx4xgFyOjViqjC5DvEUN9FyFno0gQHLjLbrGnIcNp7i7QBBj7QXlQg7+H3amhqeMOFb8ZWbh64FdXitPpnA0THWc0Nl04jxf3bolul0oS4NGd7KYS9KJ1UF5cH0OfO3BKccxE72d9j51zo+u3sUEKBPQP6Q64X1l3hLX9qICaBCx7HuGTANjZAT9STyMBIsoaPnUhMB6726MgvmQyAKYpGqjcewREBC2RbLNt4QuMF1Zkab71ZblD0xAnDWmZyw/jJNeCyqfeRVZA19KNlF/C19/SX65du17r13vkCdlJMbMgTA== X-Gm-Message-State: AOJu0YypuxnjnCoh+azX8s7VnLkcIN2NCxq5ryR41dHibXDVpDyRZ5e+ xmxT/mK54DlLQi0qpjv4b0N+2ieqaEiFXqTCY3Rjk9+zJlKY0LNkKVygRhU3+2lA2POg5UFf//a tVeddPec19D2Z96Re/wmtdpw3K6A= X-Google-Smtp-Source: AGHT+IFY0Y/UcJS7sknileL2UagN7ReFxrAWEEHMeCw0v9alkFUCpuvgoM4QBmWhVR/dsnO/cQfpgT+sNC6/yK6yero= X-Received: by 2002:a05:6214:20e2:b0:6b5:24b:f430 with SMTP id 6a1803df08f44-6b540a91d2emr16144186d6.40.1719109609327; Sat, 22 Jun 2024 19:26:49 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240621022959.9124-1-laoar.shao@gmail.com> <20240621022959.9124-7-laoar.shao@gmail.com> <20240621135142.GF1098275@kernel.org> In-Reply-To: <20240621135142.GF1098275@kernel.org> From: Yafang Shao Date: Sun, 23 Jun 2024 10:26:13 +0800 Message-ID: Subject: Re: [PATCH v3 06/11] mm/util: Deduplicate code in {kstrdup,kstrndup,kmemdup_nul} To: Simon Horman Cc: torvalds@linux-foundation.org, ebiederm@xmission.com, alexei.starovoitov@gmail.com, rostedt@goodmis.org, catalin.marinas@arm.com, akpm@linux-foundation.org, penguin-kernel@i-love.sakura.ne.jp, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, audit@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Jun 21, 2024 at 9:51=E2=80=AFPM Simon Horman wro= te: > > On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > > These three functions follow the same pattern. To deduplicate the code, > > let's introduce a common help __kstrndup(). > > > > Suggested-by: Andrew Morton > > Signed-off-by: Yafang Shao > > Hi Yafang Shao, > > Some minor nits from my side. > > > --- > > mm/internal.h | 24 ++++++++++++++++++++++++ > > mm/util.c | 27 ++++----------------------- > > 2 files changed, 28 insertions(+), 23 deletions(-) > > > > diff --git a/mm/internal.h b/mm/internal.h > > index b2c75b12014e..fd87f685739b 100644 > > --- a/mm/internal.h > > +++ b/mm/internal.h > > @@ -1521,4 +1521,28 @@ static inline void shrinker_debugfs_remove(struc= t dentry *debugfs_entry, > > void workingset_update_node(struct xa_node *node); > > extern struct list_lru shadow_nodes; > > > > +/** > > + * __kstrndup - Create a NUL-terminated string from @s, which might be= unterminated. > > + * @s: The data to stringify > > + * @len: The size of the data, including the null terminator > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memor= y > > + * > > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > > + * case of error > > + */ > > +static __always_inline char *__kstrndup(const char *s, size_t len, gfp= _t gfp) > > +{ > > + char *buf; > > + > > + buf =3D kmalloc_track_caller(len, gfp); > > + if (!buf) > > + return NULL; > > + > > + memcpy(buf, s, len); > > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > > + buf[len - 1] =3D '\0'; > > + return buf; > > +} > > + > > + > > nit: One blank line is enough. Ah, will change it. > > > #endif /* __MM_INTERNAL_H */ > > diff --git a/mm/util.c b/mm/util.c > > index 41c7875572ed..d9135c5fdf7f 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -58,17 +58,8 @@ char *kstrdup(const char *s, gfp_t gfp) > > if (!s) > > return NULL; > > > > - len =3D strlen(s) + 1; > > - buf =3D kmalloc_track_caller(len, gfp); > > - if (buf) { > > - memcpy(buf, s, len); > > - /* During memcpy(), the string might be updated to a new = value, > > - * which could be longer than the string when strlen() is > > - * called. Therefore, we need to add a null termimator. > > - */ > > - buf[len - 1] =3D '\0'; > > - } > > - return buf; > > nit: The local variable buf is now unused, and should be removed from kst= rdup(). > Likewise for kstrndup() and kmemdup_nul() > > Flagged by W=3D1 builds with gcc-13 and clang-18, and Smatch. I missed that. Thanks for pointing it out. --=20 Regards Yafang