From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DE02C443D; Fri, 21 Jun 2024 13:51:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718977908; cv=none; b=M1hcOYW4ffAK9N8oG7Yzp6yJUMoF3qrzfCVwyZLGJKKM65qZ38aBimKSxWKLL+CA6Hm4Dua3w1/GMnb0buV1+5Glv8OwuRJIB9a+4SG+/fn88kogekAvZw6vHVbItwRZhLWDOrry8T2w9YTp124l0L7fqws3Jnp3bDbsT7J5zX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718977908; c=relaxed/simple; bh=8ElvnQPorg4Uy8imgywI1nXgKQs3ZmLKdexYoFKBvac=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NuwdLi7CQKtcyp6caXuL77Ub8LZIBIcx4GiWdQF0eCGLPiJDdC9cxe3x3XdjHX0F1mRK3iCPju42wK8bh4zrGrqjj4OP515lFXEvEbGkredh0oj/6b3mLxG09YYA5io+V3nw7HcQlZIAcpRLhPEr6HPVXXP289aSk8nY5Nw1mbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UsGyxC89; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UsGyxC89" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 550E9C2BBFC; Fri, 21 Jun 2024 13:51:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718977907; bh=8ElvnQPorg4Uy8imgywI1nXgKQs3ZmLKdexYoFKBvac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UsGyxC89mordI9Vx2/gblUM+5Ftjcp3r6aWKgvC7AgxfbKbF3tjOKH0Oc8+4xZ7ka 53imU3u4kl0xmHWBQeUrPXwpUd4HV0CgvxjAnuDWJ+ESadO9DPtFhcHEFsx5/l50Bz PqCADX8QGP+tUecordMNnCcTvHzzeLNDNuubgkM1ZH0YhaycbAUJQX5AgoxWKcT6ec LoK6DITeynsMoscskznn7E6zxgUT2BnmrOQrutlHoqdl3OFBWB1zfStM0zrLF8lSLa q/3x7IxAscJ0MKpSbvImWfCwO2VqiKdnJI4j+sBQLyP7fynER53ZfDDEcEKKBhm0gu ID9btTmN8DF3w== Date: Fri, 21 Jun 2024 14:51:42 +0100 From: Simon Horman To: Yafang Shao 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 Subject: Re: [PATCH v3 06/11] mm/util: Deduplicate code in {kstrdup,kstrndup,kmemdup_nul} Message-ID: <20240621135142.GF1098275@kernel.org> References: <20240621022959.9124-1-laoar.shao@gmail.com> <20240621022959.9124-7-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <20240621022959.9124-7-laoar.shao@gmail.com> 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(struct 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 memory > + * > + * 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 = 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] = '\0'; > + return buf; > +} > + > + nit: One blank line is enough. > #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 = strlen(s) + 1; > - buf = 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] = '\0'; > - } > - return buf; nit: The local variable buf is now unused, and should be removed from kstrdup(). Likewise for kstrndup() and kmemdup_nul() Flagged by W=1 builds with gcc-13 and clang-18, and Smatch. > + len = strlen(s); > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kstrdup); > > @@ -111,12 +102,7 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp) > return NULL; > > len = strnlen(s, max); > - buf = kmalloc_track_caller(len+1, gfp); > - if (buf) { > - memcpy(buf, s, len); > - buf[len] = '\0'; > - } > - return buf; > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kstrndup); > > @@ -195,12 +181,7 @@ char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > if (!s) > return NULL; > > - buf = kmalloc_track_caller(len + 1, gfp); > - if (buf) { > - memcpy(buf, s, len); > - buf[len] = '\0'; > - } > - return buf; > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kmemdup_nul); > > -- > 2.39.1 > >