From patchwork Wed Mar 22 21:52:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin KaFai Lau X-Patchwork-Id: 13184692 X-Patchwork-Delegate: bpf@iogearbox.net 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 C5C21C74A5B for ; Wed, 22 Mar 2023 21:53:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230000AbjCVVxI (ORCPT ); Wed, 22 Mar 2023 17:53:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230026AbjCVVxG (ORCPT ); Wed, 22 Mar 2023 17:53:06 -0400 Received: from out-41.mta0.migadu.com (out-41.mta0.migadu.com [91.218.175.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F301A1B9 for ; Wed, 22 Mar 2023 14:53:00 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1679521979; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PzlyeCM47ySU8duDu+NQmGF39gNhQcOYX2NQtxGEBig=; b=Lm2BuZZjLos/OYKIapjXtXMa25okSafbTajWlHvYkDklN+Jajqx1LPf/JLJkL88GzNw3ft oFAPCLSKvABDWXdyaev0PNlbONXCbYdcgYtOcAhDmBNWnLS7HVrXelpUNwEwMA6Htf9cxC zLNoubNHgAWIBHM5PTMZ5Xcc8+gGVuw= From: Martin KaFai Lau To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@meta.com, Namhyung Kim Subject: [PATCH v3 bpf-next 3/5] bpf: Use bpf_mem_cache_alloc/free for bpf_local_storage Date: Wed, 22 Mar 2023 14:52:44 -0700 Message-Id: <20230322215246.1675516-4-martin.lau@linux.dev> In-Reply-To: <20230322215246.1675516-1-martin.lau@linux.dev> References: <20230322215246.1675516-1-martin.lau@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Martin KaFai Lau This patch uses bpf_mem_cache_alloc/free for allocating and freeing bpf_local_storage for task and cgroup storage. The changes are similar to the previous patch. A few things that worth to mention for bpf_local_storage: The local_storage is freed when the last selem is deleted. Before deleting a selem from local_storage, it needs to retrieve the local_storage->smap because the bpf_selem_unlink_storage_nolock() may have set it to NULL. Note that local_storage->smap may have already been NULL when the selem created this local_storage has been removed. In this case, call_rcu will be used to free the local_storage. Also, the bpf_ma (true or false) value is needed before calling bpf_local_storage_free(). The bpf_ma can either be obtained from the local_storage->smap (if available) or any of its selem's smap. A new helper check_storage_bpf_ma() is added to obtain bpf_ma for a deleting bpf_local_storage. When bpf_local_storage_alloc getting a reused memory, all fields are either in the correct values or will be initialized. 'cache[]' must already be all NULLs. 'list' must be empty. Others will be initialized. Cc: Namhyung Kim Signed-off-by: Martin KaFai Lau --- include/linux/bpf_local_storage.h | 1 + kernel/bpf/bpf_local_storage.c | 130 ++++++++++++++++++++++++++---- 2 files changed, 116 insertions(+), 15 deletions(-) diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index 30efbcab2798..173ec7f43ed1 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -57,6 +57,7 @@ struct bpf_local_storage_map { u16 elem_size; u16 cache_idx; struct bpf_mem_alloc selem_ma; + struct bpf_mem_alloc storage_ma; bool bpf_ma; }; diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index 309ea727a5cb..dab2ff4c99d9 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -111,33 +111,74 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, return NULL; } +/* rcu tasks trace callback for bpf_ma == false */ +static void __bpf_local_storage_free_trace_rcu(struct rcu_head *rcu) +{ + struct bpf_local_storage *local_storage; + + /* If RCU Tasks Trace grace period implies RCU grace period, do + * kfree(), else do kfree_rcu(). + */ + local_storage = container_of(rcu, struct bpf_local_storage, rcu); + if (rcu_trace_implies_rcu_gp()) + kfree(local_storage); + else + kfree_rcu(local_storage, rcu); +} + static void bpf_local_storage_free_rcu(struct rcu_head *rcu) { struct bpf_local_storage *local_storage; local_storage = container_of(rcu, struct bpf_local_storage, rcu); - kfree(local_storage); + bpf_mem_cache_raw_free(local_storage); } static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu) { - /* If RCU Tasks Trace grace period implies RCU grace period, do - * kfree(), else do kfree_rcu(). - */ if (rcu_trace_implies_rcu_gp()) bpf_local_storage_free_rcu(rcu); else call_rcu(rcu, bpf_local_storage_free_rcu); } +/* Handle bpf_ma == false */ +static void __bpf_local_storage_free(struct bpf_local_storage *local_storage, + bool vanilla_rcu) +{ + if (vanilla_rcu) + kfree_rcu(local_storage, rcu); + else + call_rcu_tasks_trace(&local_storage->rcu, + __bpf_local_storage_free_trace_rcu); +} + static void bpf_local_storage_free(struct bpf_local_storage *local_storage, - bool reuse_now) + struct bpf_local_storage_map *smap, + bool bpf_ma, bool reuse_now) { - if (!reuse_now) + if (!bpf_ma) { + __bpf_local_storage_free(local_storage, reuse_now); + return; + } + + if (!reuse_now) { call_rcu_tasks_trace(&local_storage->rcu, bpf_local_storage_free_trace_rcu); - else + return; + } + + if (smap) { + migrate_disable(); + bpf_mem_cache_free(&smap->storage_ma, local_storage); + migrate_enable(); + } else { + /* smap could be NULL if the selem that triggered + * this 'local_storage' creation had been long gone. + * In this case, directly do call_rcu(). + */ call_rcu(&local_storage->rcu, bpf_local_storage_free_rcu); + } } /* rcu tasks trace callback for bpf_ma == false */ @@ -260,11 +301,47 @@ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_stor return free_local_storage; } +static bool check_storage_bpf_ma(struct bpf_local_storage *local_storage, + struct bpf_local_storage_map *storage_smap, + struct bpf_local_storage_elem *selem) +{ + + struct bpf_local_storage_map *selem_smap; + + /* local_storage->smap may be NULL. If it is, get the bpf_ma + * from any selem in the local_storage->list. The bpf_ma of all + * local_storage and selem should have the same value + * for the same map type. + * + * If the local_storage->list is already empty, the caller will not + * care about the bpf_ma value also because the caller is not + * responsibile to free the local_storage. + */ + + if (storage_smap) + return storage_smap->bpf_ma; + + if (!selem) { + struct hlist_node *n; + + n = rcu_dereference_check(hlist_first_rcu(&local_storage->list), + bpf_rcu_lock_held()); + if (!n) + return false; + + selem = hlist_entry(n, struct bpf_local_storage_elem, snode); + } + selem_smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held()); + + return selem_smap->bpf_ma; +} + static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, bool reuse_now) { + struct bpf_local_storage_map *storage_smap; struct bpf_local_storage *local_storage; - bool free_local_storage = false; + bool bpf_ma, free_local_storage = false; unsigned long flags; if (unlikely(!selem_linked_to_storage_lockless(selem))) @@ -273,6 +350,10 @@ static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, local_storage = rcu_dereference_check(selem->local_storage, bpf_rcu_lock_held()); + storage_smap = rcu_dereference_check(local_storage->smap, + bpf_rcu_lock_held()); + bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, selem); + raw_spin_lock_irqsave(&local_storage->lock, flags); if (likely(selem_linked_to_storage(selem))) free_local_storage = bpf_selem_unlink_storage_nolock( @@ -280,7 +361,7 @@ static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, raw_spin_unlock_irqrestore(&local_storage->lock, flags); if (free_local_storage) - bpf_local_storage_free(local_storage, reuse_now); + bpf_local_storage_free(local_storage, storage_smap, bpf_ma, reuse_now); } void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, @@ -400,8 +481,15 @@ int bpf_local_storage_alloc(void *owner, if (err) return err; - storage = bpf_map_kzalloc(&smap->map, sizeof(*storage), - gfp_flags | __GFP_NOWARN); + if (smap->bpf_ma) { + migrate_disable(); + storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags); + migrate_enable(); + } else { + storage = bpf_map_kzalloc(&smap->map, sizeof(*storage), + gfp_flags | __GFP_NOWARN); + } + if (!storage) { err = -ENOMEM; goto uncharge; @@ -447,7 +535,7 @@ int bpf_local_storage_alloc(void *owner, return 0; uncharge: - bpf_local_storage_free(storage, true); + bpf_local_storage_free(storage, smap, smap->bpf_ma, true); mem_uncharge(smap, owner, sizeof(*storage)); return err; } @@ -660,11 +748,15 @@ int bpf_local_storage_map_check_btf(const struct bpf_map *map, void bpf_local_storage_destroy(struct bpf_local_storage *local_storage) { + struct bpf_local_storage_map *storage_smap; struct bpf_local_storage_elem *selem; - bool free_storage = false; + bool bpf_ma, free_storage = false; struct hlist_node *n; unsigned long flags; + storage_smap = rcu_dereference_check(local_storage->smap, bpf_rcu_lock_held()); + bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, NULL); + /* 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 @@ -692,7 +784,7 @@ void bpf_local_storage_destroy(struct bpf_local_storage *local_storage) raw_spin_unlock_irqrestore(&local_storage->lock, flags); if (free_storage) - bpf_local_storage_free(local_storage, true); + bpf_local_storage_free(local_storage, storage_smap, bpf_ma, true); } u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map) @@ -755,6 +847,12 @@ bpf_local_storage_map_alloc(union bpf_attr *attr, err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false); if (err) goto free_smap; + + err = bpf_mem_alloc_init(&smap->storage_ma, sizeof(struct bpf_local_storage), false); + if (err) { + bpf_mem_alloc_destroy(&smap->selem_ma); + goto free_smap; + } } smap->cache_idx = bpf_local_storage_cache_idx_get(cache); @@ -829,8 +927,10 @@ void bpf_local_storage_map_free(struct bpf_map *map, */ synchronize_rcu(); - if (smap->bpf_ma) + if (smap->bpf_ma) { bpf_mem_alloc_destroy(&smap->selem_ma); + bpf_mem_alloc_destroy(&smap->storage_ma); + } kvfree(smap->buckets); bpf_map_area_free(smap); }