Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 23 May 2023 13:55:38 -0400
From:   "Liam R. Howlett" <Liam.Howlett@Oracle.com>
To:     Peng Zhang <zhangpeng.00@bytedance.com>
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org
Subject: Re: [PATCH v3 07/10] maple_tree: Add comments and some minor
 cleanups to mas_wr_append()
Message-ID: <20230523175538.etpthyoq3oqtslbo@revolver>
Mail-Followup-To: "Liam R. Howlett" <Liam.Howlett@Oracle.com>,
        Peng Zhang <zhangpeng.00@bytedance.com>, akpm@linux-foundation.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        maple-tree@lists.infradead.org
References: <20230522050656.96215-1-zhangpeng.00@bytedance.com>
 <20230522050656.96215-8-zhangpeng.00@bytedance.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230522050656.96215-8-zhangpeng.00@bytedance.com>
User-Agent: NeoMutt/20220429
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?D/yu6ngORBZ/Z6M/3d1hh+qbWKxxYu5MGZnGF6pW5UBPEbM2ajeZtUktH7nk?=
 =?us-ascii?Q?eybiLCDqyuD9MeGimY1oNWGSQceq77HGBhJLGJWs3z/HR6HvFuinkwDm3stP?=
 =?us-ascii?Q?ChkmdNVl8XJUjXCd3BCXOszemTLoTmdtwYhGznXz1Z6OLGR6Z8q8ozKdNHmb?=
 =?us-ascii?Q?K0imoGv0fXR/E6qtI8Q+rX9DlPUV1eTHbPPB0NdK1DwC5IO/9kLWHmvtzfcQ?=
 =?us-ascii?Q?XMmmcBzRnJdHjCiUHvNwa9iV2GZbL3kDaqTQ7/+Yl2QIOF30ykaJT4Zryrmy?=
 =?us-ascii?Q?t5E+G/tpaI3kJVJxT6UpOOhbqH8JbXAUqx1q5xHVoKP9mnBNy/+ddbnXSN63?=
 =?us-ascii?Q?Jk1vG0hzd3obm9qPaqrvphspIkU0fYxiOv/WNlTTXL7mFnSszsgiHZBIZ831?=
 =?us-ascii?Q?WmaNBWsF2jckpXZk5N0Jucs2LbaNaD3ldLnRkQtv1ZDhHpZWbq6IXpOfGZg7?=
 =?us-ascii?Q?qHOvNx7MeVFjEeH/RS0cr3/wfpq6QEIva9Q2IimFb0m58uOtmJARV5QxqXBR?=
 =?us-ascii?Q?Or9m8kLphRRr0KX/1vNHukUdKBggdZFCi74racgW6+B2azZ4tVe8QHorNZTz?=
 =?us-ascii?Q?igwqWRVZgi1HY1788bwzLxO6KysJhEciHRjQMKRlDH+1Sv+BN0S83rrZWs2K?=
 =?us-ascii?Q?K8NTSO9LyUCe34v/6P8PSvPch0umipTHbNgFqjcEpDKANovdWN4bVJIFUoBU?=
 =?us-ascii?Q?+3S/1bWw0hhMVAVZ8eHwvJfhwnUcZW3Iy4TzBYSBomMu4gnlp3oVAWzmwYai?=
 =?us-ascii?Q?hYk3SGV5PxT1CnCdfI+gnkOVgVSPHa8FJVw8Zf0NjJBhh0GFViIk2+paar8x?=
 =?us-ascii?Q?dYH8uRi4qFsRzkpeCv2hO0ov2WfcGCKveJdB6iod1lTTM1R79KLoygsR+NYw?=
 =?us-ascii?Q?u2x6ZMXN0zI09nez2HqhPNcnl4O5bEWT3H/pMb4MaXFOh8baheJCI5y+eXj4?=
 =?us-ascii?Q?HocjvEnxIMB1nXGLMqap9kzgqhNrsQnlQ1/iKUeCFLIb78JJ8wse1iqWNVAS?=
 =?us-ascii?Q?wiVL5bknm8Z2JXjLe8nPnkyqPZFPek14wS0JuwIHvBF4zTw8PoH5Y0c8hOsY?=
 =?us-ascii?Q?Ii2HBIDSeFeGcZWXZG3z51ZcZ0X8lt+SHVs35xe3DpER1yG9l7EnFpg+j/Nm?=
 =?us-ascii?Q?vs8nsD7LVzePt6mFpRXD5tGJ/tnCt/R1Ai1dFbAGIydoZ4044PwK3Ba9Da5U?=
 =?us-ascii?Q?lUnPfisO4EbihqJ8UNyH4eBCt3Est/2lb3IBLnkKTDtz6FLBmEwtSTVfvsmF?=
 =?us-ascii?Q?sjMW3+IXUcGJHsDRqCKNHvLgY8UMSKk2zpGFxxQ0qartQSpXipMiovlA/F7I?=
 =?us-ascii?Q?e6eNfkaep75960knPNZ17MCkvzpMCJo/bbsJqLJH4Wxd936nybHZGpasliYD?=
 =?us-ascii?Q?rI8S+LQHIXoD1AZtLMSlVrrVLYxapndC+XV9lsS0FQwjKsWWf+n36pxd3VdL?=
 =?us-ascii?Q?uhoC/IUflXplhFXcGWIP8oHXvC3YyeOAHRJzLV4LbdaiVlv1XGOq/dcb4jDP?=
 =?us-ascii?Q?TQhceyrOCNXsipirL/tJOic0DDuAr2zusgQwRktEGW4zEortiG6nmKtyILva?=
 =?us-ascii?Q?HuH/3jPGNmUYUEgk0kc1wZMc0F1Se9X33UsVtmE0Jt6S55cAz8gY/sY3Jzps?=
 =?us-ascii?Q?Mw=3D=3D?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?us-ascii?Q?dJdq9Ijlo1+9hO1el1oJ+Q9tlVjS1Q061BcDHS0zws9cZim4HcBTQnolYIU7?=
 =?us-ascii?Q?Y6tg+llQnMu2+Yz3UfCEq8SOwlzHwCLPw0ZVyWWpSL8zzWS/V7Aqu2Ir+Ddx?=
 =?us-ascii?Q?pkPa74M8nx6fYsHOdXvXb3l5Z8vULjNLr0D8bFMmAojzY31rosUG8sVJ+QDd?=
 =?us-ascii?Q?K6TMZ8jy2pxvkx2PjGhNc7h4TTHI7Y0nx8Y3aB5V5mIzHFU7j9s8M5cWA9dK?=
 =?us-ascii?Q?4OLZlmO7GieuAlhSmAcUJ2YExX+nBsgucwbNXwE2DPfFbVkS7dbOHTHvaPqt?=
 =?us-ascii?Q?tEmMHr943CwYSm456N8gMqge3CxYgetF0FJ4+aQX/aTWt/N/tx+RyOydrs2R?=
 =?us-ascii?Q?4fPPAytJhuDNtc37rHKvOIi/istgam/9toVBV3lzqQpsAkF1WnBf0/1zuBph?=
 =?us-ascii?Q?66ut/LdYy5HSyUJ6zuZUKm1OPlnozxWEa8NWI1DAtg1ntk7Qwv9qVATJcyEs?=
 =?us-ascii?Q?PJ1FMSOPojNMgxADvyxc+st/I4mJf5N4sRubAwiN6fNb0KzUn0pXk57J8ZS6?=
 =?us-ascii?Q?S75CNX5/zIMfOD/hgqIawaWuoiCmV+ZIUg4O/JQsmvAOq082NSKEPkNAubpV?=
 =?us-ascii?Q?fTe0uBNRb0eDyJAvKgQAhdSJiNIrMX4+y/jlAszwIUMFnJ043c2F+8smFxyB?=
 =?us-ascii?Q?3h9X9xWtqT8qcdNGCkBGtxkONcLr3poPx4M2TJ7JXm7Gq5yzhNlMSiYSDUvk?=
 =?us-ascii?Q?ho7L7rNewm2suI3Bap9X6Tp7rZ5lDfHVkL8JgXJjik4m+hcikeSnQ9IkeNds?=
 =?us-ascii?Q?6gcwD1aL0QQ7ra+5PKZKQ6maEF7c8xLWimiCu1YxO/pS1QH9oY6J90+PI9bR?=
 =?us-ascii?Q?SzI+gJb31S3ePdULmJX6kPKSUlWGJWFX/bou0ojZiRG2JUJqi/lIEB0rcCRj?=
 =?us-ascii?Q?lru/3O+9VGjErMXyWXR54SGRwitUwG5bm0ONNUd0GgGF1fILcnuz0znAzSgw?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: d7524661-c981-4a8a-bff5-08db5bb6ec2b
X-MS-Exchange-CrossTenant-AuthSource: SN6PR10MB3022.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 May 2023 17:55:40.9389
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: d3AemTqvoAFf4gtm4OxchD0Q/LhaVnUpI0WssSJdjFCGudmnS75b5JlL0Qx1uNr+TKQlA/SnDDZMxAAmqn4aGw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR10MB4527
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26
 definitions=2023-05-23_11,2023-05-23_02,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxscore=0
 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=0 adultscore=0
 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2304280000 definitions=main-2305230144
X-Proofpoint-GUID: SQVt8MfREvyAUmUVlbsTpM7yTqvTC2UW
X-Proofpoint-ORIG-GUID: SQVt8MfREvyAUmUVlbsTpM7yTqvTC2UW
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

* Peng Zhang <zhangpeng.00@bytedance.com> [230522 01:07]:
> 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 <zhangpeng.00@bytedance.com>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
>  lib/maple_tree.c | 47 +++++++++++++++++++++++------------------------
>  1 file changed, 23 insertions(+), 24 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 0550a07355d7..afbfdcdde5db 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4312,6 +4312,12 @@ 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;
> @@ -4319,34 +4325,30 @@ 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->index != wr_mas->r_min) && (mas->last == wr_mas->r_max)) {
> -		if (new_end < node_pivots)
> -			wr_mas->pivots[new_end] = wr_mas->pivots[end];
> +	if (mas->offset != wr_mas->node_end)
> +		return false;
>  
> -		if (new_end < node_pivots)
> -			ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
> +	if (new_end < node_pivots) {
> +		wr_mas->pivots[new_end] = wr_mas->pivots[end];
> +		ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
> +	}
>  
> +	if (mas->last == wr_mas->r_max) {
> +		/* Append to end of range */
>  		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)) {
> -		if (new_end < node_pivots)
> -			wr_mas->pivots[new_end] = wr_mas->pivots[end];
> -
> +		mas->offset = new_end;
> +	} else {
> +		/* Append to start of range */
>  		rcu_assign_pointer(wr_mas->slots[new_end], wr_mas->content);
> -		if (new_end < node_pivots)
> -			ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
> -
>  		wr_mas->pivots[end] = mas->last;
>  		rcu_assign_pointer(wr_mas->slots[end], wr_mas->entry);
> -		return true;
>  	}
>  
> -	return false;
> +	if (!wr_mas->content || !wr_mas->entry)
> +		mas_update_gap(mas);
> +
> +	return  true;
>  }
>  
>  /*
> @@ -4386,12 +4388,9 @@ 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
>