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[192.55.52.93]) by mx.google.com with ESMTPS id f17si6952689plj.17.2019.08.09.01.31.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Aug 2019 01:31:47 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of richardw.yang@linux.intel.com designates 192.55.52.93 as permitted sender) client-ip=192.55.52.93; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of richardw.yang@linux.intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=richardw.yang@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Aug 2019 01:31:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,364,1559545200"; d="scan'208";a="375132991" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga006.fm.intel.com with ESMTP; 09 Aug 2019 01:31:45 -0700 Date: Fri, 9 Aug 2019 16:31:22 +0800 From: Wei Yang To: Vlastimil Babka Cc: Wei Yang , akpm@linux-foundation.org, mhocko@suse.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/mmap.c: refine find_vma_prev with rb_last Message-ID: <20190809083122.GA32128@richard> Reply-To: Wei Yang References: <20190809001928.4950-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) 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: On Fri, Aug 09, 2019 at 10:03:20AM +0200, Vlastimil Babka wrote: >On 8/9/19 2:19 AM, Wei Yang wrote: >> When addr is out of the range of the whole rb_tree, pprev will points to >> the right-most node. rb_tree facility already provides a helper >> function, rb_last, to do this task. We can leverage this instead of >> re-implement it. >> >> This patch refines find_vma_prev with rb_last to make it a little nicer >> to read. >> >> Signed-off-by: Wei Yang > >Acked-by: Vlastimil Babka > >Nit below: > >> --- >> v2: leverage rb_last >> --- >> mm/mmap.c | 9 +++------ >> 1 file changed, 3 insertions(+), 6 deletions(-) >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 7e8c3e8ae75f..f7ed0afb994c 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -2270,12 +2270,9 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr, >> if (vma) { >> *pprev = vma->vm_prev; >> } else { >> - struct rb_node *rb_node = mm->mm_rb.rb_node; >> - *pprev = NULL; >> - while (rb_node) { >> - *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); >> - rb_node = rb_node->rb_right; >> - } >> + struct rb_node *rb_node = rb_last(&mm->mm_rb); >> + *pprev = !rb_node ? NULL : >> + rb_entry(rb_node, struct vm_area_struct, vm_rb); > >It's perhaps more common to write it like: >*pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL; > Do you prefer me to send v3 with this updated? >> } >> return vma; >> } >> -- Wei Yang Help you, Help me