From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AB6AC05027 for ; Fri, 17 Feb 2023 11:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230165AbjBQLty (ORCPT ); Fri, 17 Feb 2023 06:49:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbjBQLtx (ORCPT ); Fri, 17 Feb 2023 06:49:53 -0500 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB85B5BD86 for ; Fri, 17 Feb 2023 03:49:51 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4PJ98p6Tgjz4f3pFX for ; Fri, 17 Feb 2023 19:49:46 +0800 (CST) Received: from [10.174.176.117] (unknown [10.174.176.117]) by APP4 (Coremail) with SMTP id gCh0CgDHeq7Zae9j2+YrDw--.64647S2; Fri, 17 Feb 2023 19:49:48 +0800 (CST) Subject: Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr() To: dm-devel@redhat.com, Mike Snitzer Cc: linux-kernel@vger.kernel.org, Alasdair Kergon , "houtao1@huawei.com" References: <20221216042353.3132139-1-houtao@huaweicloud.com> <5d93f5fc-05fa-906e-b2e9-0e9abcdf16f6@huaweicloud.com> From: Hou Tao Message-ID: Date: Fri, 17 Feb 2023 19:49:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <5d93f5fc-05fa-906e-b2e9-0e9abcdf16f6@huaweicloud.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-CM-TRANSID: gCh0CgDHeq7Zae9j2+YrDw--.64647S2 X-Coremail-Antispam: 1UD129KBjvJXoWxJr13CF1DAF15JF4xJw13Jwb_yoW8uFWDpr 1FgFWa9r4kJFsF9r42vanI9Fyjkw1YkrWUGr1xKayj93Wq9w18GayUGFWxWFyrAFyxAF4Y gr1Ig3y5CFWDA37anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkjb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxk0xIA0c2IEe2xFo4CEbIxvr21l42xK82IYc2Ij 64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x 8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE 2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42 xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIE c7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UE-erUUUUU= X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping ? Any comments on this clean up patch ? On 1/31/2023 9:44 AM, Hou Tao wrote: > ping ? Any comments on this clean up patch ? > > On 1/18/2023 9:16 PM, Hou Tao wrote: >> ping ? >> >> On 12/16/2022 12:23 PM, Hou Tao wrote: >>> From: Hou Tao >>> >>> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring >>> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must >>> have not been removed and hc->md must still be md. >>> >>> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr >>> as NULL, so in dm_copy_name_and_uuid() after acquiring >>> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned >>> hc must still be alive and hc->md must still be md. >>> >>> So removing these unnecessary hc->md != md checks when using >>> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired. >>> >>> Signed-off-by: Hou Tao >>> --- >>> drivers/md/dm-ioctl.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c >>> index 3bfc1583c20a..2a86524661d1 100644 >>> --- a/drivers/md/dm-ioctl.c >>> +++ b/drivers/md/dm-ioctl.c >>> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src >>> >>> down_read(&_hash_lock); >>> hc = dm_get_mdptr(md); >>> - if (!hc || hc->md != md) { >>> + if (!hc) { >>> DMERR("device has been removed from the dev hash table."); >>> goto out; >>> } >>> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si >>> /* stage inactive table */ >>> down_write(&_hash_lock); >>> hc = dm_get_mdptr(md); >>> - if (!hc || hc->md != md) { >>> + if (!hc) { >>> DMERR("device has been removed from the dev hash table."); >>> up_write(&_hash_lock); >>> r = -ENXIO; >>> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid) >>> >>> mutex_lock(&dm_hash_cells_mutex); >>> hc = dm_get_mdptr(md); >>> - if (!hc || hc->md != md) { >>> + if (!hc) { >>> r = -ENXIO; >>> goto out; >>> } > .