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 5A99CC67871 for ; Mon, 24 Oct 2022 19:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233287AbiJXTde (ORCPT ); Mon, 24 Oct 2022 15:33:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233332AbiJXTdM (ORCPT ); Mon, 24 Oct 2022 15:33:12 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82372476C5 for ; Mon, 24 Oct 2022 11:03:41 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-360a7ff46c3so97538247b3.12 for ; Mon, 24 Oct 2022 11:03:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=1W4COW227y1aljclFVB4DMM0UVXXW3Ga8dwPdHFh004=; b=Ai4e64uWR6Fn6sf8KZrJVl7N1QJ4SSOruj07zkal+UJJ+/elp6Rztzzh7VBceGOiX0 4z6CzCpcMAY+ytKlb9nl8wvRjlWrzHZgtgRYTZcp7y89f5KZuY6tlSDKY2wUiraKQVXs sRtk+nkAkcSnD6KsoCcXl7hu03w1uNnSYDIXrrCWOx5pf8W6v4mVV0TYqju37cmYcVhB 3hiJa2YPH+dUFLiGfjdFNnkXm2ckCghqJMV/U8lwSVe7UgAkyXDzblFU8l5wg4MUe5wr QxHJB3CwIHTVWPMgu6ky7VoPuD08RPAT0r1aDIUHXDGkfaetfcXtTHRUoFywPXs2M/Uf Xpug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1W4COW227y1aljclFVB4DMM0UVXXW3Ga8dwPdHFh004=; b=oVqBFV15bgyMsGn8dka9tkM9X8eNQzCtQGM0F4X26Y2oYiiB5FsYHk/QIcJ4wJEYP0 qd9KG4P2my5Ugh2iH1JJibugfah6Cd60BNaGDOvjPPV4mNUoixMoc0SCWUpzjXBloQjK fVxMXw+eHY6x+Rx35rVcbcb9JEU2mkMXbXxbKxrLUg9hGyqUInUkUs5tvjppLCustd4v 2s5g1hp6m7PxHuthOAkTijSwppqRB82NJIKxXXXvCYesXeSdMdBfLNQRk8A1Ppf5gaYU E1O8lRw2A9weHiLKjLoJgDFFo3wRTxD3TUnTFyACB0A5RyBKi72XVWudQgy9tm+PNJ9G o7jQ== X-Gm-Message-State: ACrzQf1Kpl03xI4tlPUPV9yakpC/DqeIZ02uTGQQnrq7zaVszplCvZmk 6mHPg5bFk9KLpkddRrRt5KdmGBA= X-Google-Smtp-Source: AMsMyM5+edUCkiqlB86Nctg+Hv2aZNAeB20G0xodkvYJSik5eECA+ZdKywcqWybGmB6B0UPhQdpNXis= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a25:c713:0:b0:6ca:203:504f with SMTP id w19-20020a25c713000000b006ca0203504fmr23725194ybe.574.1666634544720; Mon, 24 Oct 2022 11:02:24 -0700 (PDT) Date: Mon, 24 Oct 2022 11:02:23 -0700 In-Reply-To: <20221023180524.2859994-1-yhs@fb.com> Mime-Version: 1.0 References: <20221023180514.2857498-1-yhs@fb.com> <20221023180524.2859994-1-yhs@fb.com> Message-ID: Subject: Re: [PATCH bpf-next v4 2/7] bpf: Refactor inode/task/sk storage map_{alloc,free}() for reuse From: sdf@google.com To: Yonghong Song Cc: bpf@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, KP Singh , Martin KaFai Lau , Tejun Heo , David Vernet Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 10/23, Yonghong Song wrote: > Refactor codes so that inode/task/sk storage map_{alloc,free} > can maximally share the same code. There is no functionality change. Does it make sense to also do following? (see below, untested) We aren't saving much code-wise here, but at least we won't have three copies of the same long comment. diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index 7ea18d4da84b..e4b0b04d081b 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -138,6 +138,8 @@ int bpf_local_storage_map_check_btf(const struct bpf_map *map, const struct btf_type *key_type, const struct btf_type *value_type); +bool bpf_local_storage_unlink_nolock(struct bpf_local_storage *local_storage); + void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem); diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index 5f7683b19199..5313cb0b7181 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -56,11 +56,9 @@ static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode, void bpf_inode_storage_free(struct inode *inode) { - struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; bool free_inode_storage = false; struct bpf_storage_blob *bsb; - struct hlist_node *n; bsb = bpf_inode(inode); if (!bsb) @@ -74,30 +72,11 @@ void bpf_inode_storage_free(struct inode *inode) return; } - /* Neither the bpf_prog nor the bpf-map's syscall - * could be modifying the local_storage->list now. - * Thus, no elem can be added-to or deleted-from the - * local_storage->list by the bpf_prog or by the bpf-map's syscall. - * - * It is racing with bpf_local_storage_map_free() alone - * when unlinking elem from the local_storage->list and - * the map's bucket->list. - */ raw_spin_lock_bh(&local_storage->lock); - hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { - /* Always unlink from map before unlinking from - * local_storage. - */ - bpf_selem_unlink_map(selem); - free_inode_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, false, false); - } + free_inode_storage = bpf_local_storage_unlink_nolock(local_storage); raw_spin_unlock_bh(&local_storage->lock); rcu_read_unlock(); - /* free_inoode_storage should always be true as long as - * local_storage->list was non-empty. - */ if (free_inode_storage) kfree_rcu(local_storage, rcu); } diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index 9dc6de1cf185..0ea754953242 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -98,6 +98,36 @@ void bpf_local_storage_free_rcu(struct rcu_head *rcu) kfree_rcu(local_storage, rcu); } +bool bpf_local_storage_unlink_nolock(struct bpf_local_storage *local_storage) +{ + struct bpf_local_storage_elem *selem; + bool free_storage = false; + struct hlist_node *n; + + /* Neither the bpf_prog nor the bpf-map's syscall + * could be modifying the local_storage->list now. + * Thus, no elem can be added-to or deleted-from the + * local_storage->list by the bpf_prog or by the bpf-map's syscall. + * + * It is racing with bpf_local_storage_map_free() alone + * when unlinking elem from the local_storage->list and + * the map's bucket->list. + */ + hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { + /* Always unlink from map before unlinking from + * local_storage. + */ + bpf_selem_unlink_map(selem); + free_storage = bpf_selem_unlink_storage_nolock( + local_storage, selem, false, false); + } + + /* free_storage should always be true as long as + * local_storage->list was non-empty. + */ + return free_storage; +} + static void bpf_selem_free_rcu(struct rcu_head *rcu) { struct bpf_local_storage_elem *selem; diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c index 6f290623347e..60887c25504b 100644 --- a/kernel/bpf/bpf_task_storage.c +++ b/kernel/bpf/bpf_task_storage.c @@ -71,10 +71,8 @@ task_storage_lookup(struct task_struct *task, struct bpf_map *map, void bpf_task_storage_free(struct task_struct *task) { - struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; bool free_task_storage = false; - struct hlist_node *n; unsigned long flags; rcu_read_lock(); @@ -85,32 +83,13 @@ void bpf_task_storage_free(struct task_struct *task) return; } - /* Neither the bpf_prog nor the bpf-map's syscall - * could be modifying the local_storage->list now. - * Thus, no elem can be added-to or deleted-from the - * local_storage->list by the bpf_prog or by the bpf-map's syscall. - * - * It is racing with bpf_local_storage_map_free() alone - * when unlinking elem from the local_storage->list and - * the map's bucket->list. - */ bpf_task_storage_lock(); raw_spin_lock_irqsave(&local_storage->lock, flags); - hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { - /* Always unlink from map before unlinking from - * local_storage. - */ - bpf_selem_unlink_map(selem); - free_task_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, false, false); - } + free_task_storage = bpf_local_storage_unlink_nolock(local_storage); raw_spin_unlock_irqrestore(&local_storage->lock, flags); bpf_task_storage_unlock(); rcu_read_unlock(); - /* free_task_storage should always be true as long as - * local_storage->list was non-empty. - */ if (free_task_storage) kfree_rcu(local_storage, rcu); }