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Thu, 18 May 2023 02:27:08 -0700 (PDT) Received: from [10.200.9.101] ([139.177.225.249]) by smtp.gmail.com with ESMTPSA id m8-20020aa79008000000b0064ca36ebb50sm950648pfo.93.2023.05.18.02.27.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 May 2023 02:27:08 -0700 (PDT) Message-ID: <8a52ce18-823c-7d75-30b7-e72a8bcf5665@bytedance.com> Date: Thu, 18 May 2023 17:27:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH v2 07/10] maple_tree: Add comments and some minor cleanups to mas_wr_append() To: "Liam R. Howlett" References: <20230517085809.86522-1-zhangpeng.00@bytedance.com> <20230517085809.86522-8-zhangpeng.00@bytedance.com> <20230517193353.xwd6vztfjqxesyl6@revolver> Cc: Peng Zhang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org From: Peng Zhang In-Reply-To: <20230517193353.xwd6vztfjqxesyl6@revolver> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: gioauzioodfexi6mde5t7soe5a6b3j14 X-Rspam-User: X-Rspamd-Queue-Id: DEBC2C0009 X-Rspamd-Server: rspam07 X-HE-Tag: 1684402029-959459 X-HE-Meta: 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 CIurJXle 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 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: 在 2023/5/18 03:33, Liam R. Howlett 写道: > * Peng Zhang [230517 04:59]: >> Add comment for mas_wr_append(), move mas_update_gap() into >> mas_wr_append(), and other cleanups to make mas_wr_modify() cleaner. >> >> Signed-off-by: Peng Zhang >> --- >> lib/maple_tree.c | 33 ++++++++++++++++++++------------- >> 1 file changed, 20 insertions(+), 13 deletions(-) >> >> diff --git a/lib/maple_tree.c b/lib/maple_tree.c >> index 3b9d227f3d7d..bbe4c6f2858c 100644 >> --- a/lib/maple_tree.c >> +++ b/lib/maple_tree.c >> @@ -4308,6 +4308,12 @@ static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas) >> return new_end; >> } >> >> +/* >> + * mas_wr_append: Attempt to append >> + * @wr_mas: the maple write state >> + * >> + * Return: True if appended, false otherwise >> + */ >> static inline bool mas_wr_append(struct ma_wr_state *wr_mas) >> { >> unsigned char end = wr_mas->node_end; >> @@ -4315,7 +4321,11 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas) >> struct ma_state *mas = wr_mas->mas; >> unsigned char node_pivots = mt_pivots[wr_mas->type]; >> >> + if (!(mas->offset == wr_mas->node_end)) >> + return false; >> + >> if ((mas->index != wr_mas->r_min) && (mas->last == wr_mas->r_max)) { >> + /* Append to end of range */ >> if (new_end < node_pivots) >> wr_mas->pivots[new_end] = wr_mas->pivots[end]; >> >> @@ -4323,13 +4333,10 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas) >> ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end); >> >> rcu_assign_pointer(wr_mas->slots[new_end], wr_mas->entry); >> - mas->offset = new_end; >> wr_mas->pivots[end] = mas->index - 1; >> - >> - return true; >> - } >> - >> - if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) { >> + mas->offset = new_end; >> + } else if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) { >> + /* Append to start of range */ >> if (new_end < node_pivots) >> wr_mas->pivots[new_end] = wr_mas->pivots[end]; >> >> @@ -4339,10 +4346,13 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas) >> >> wr_mas->pivots[end] = mas->last; >> rcu_assign_pointer(wr_mas->slots[end], wr_mas->entry); >> - return true; >> + } else { >> + return false; > > I don't think we can get here with your changes, what do you think? If > so, we can move the metadata setting to the outside of the if/else. I > checked by adding a BUG_ON() and the test code never gets here. > > My thinking is, we know offset == node_end and new_end == node_end + 1.. > so we must be inserting into the last slot and only adding one entry. Yes, I'll address this in v3. Thanks. > >> } >> >> - return false; >> + if (!wr_mas->content || !wr_mas->entry) >> + mas_update_gap(mas); >> + return true; >> } >> >> /* >> @@ -4382,12 +4392,9 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas) >> if (new_end >= mt_slots[wr_mas->type]) >> goto slow_path; >> >> - if (wr_mas->entry && (wr_mas->node_end < mt_slots[wr_mas->type] - 1) && >> - (mas->offset == wr_mas->node_end) && mas_wr_append(wr_mas)) { >> - if (!wr_mas->content || !wr_mas->entry) >> - mas_update_gap(mas); >> + /* Attempt to append */ >> + if (new_end == wr_mas->node_end + 1 && mas_wr_append(wr_mas)) >> return; >> - } >> >> if ((wr_mas->offset_end - mas->offset <= 1) && mas_wr_slot_store(wr_mas)) >> return; >> -- >> 2.20.1 >>