From 156c977c539e87e173f505b23989d7b0ec0bc7d8 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:14 +0800 Subject: [PATCH 1/9] bpf: Remove unnecessary check when updating LPM trie MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When "node->prefixlen == matchlen" is true, it means that the node is fully matched. If "node->prefixlen == key->prefixlen" is false, it means the prefix length of key is greater than the prefix length of node, otherwise, matchlen will not be equal with node->prefixlen. However, it also implies that the prefix length of node must be less than max_prefixlen. Therefore, "node->prefixlen == trie->max_prefixlen" will always be false when the check of "node->prefixlen == key->prefixlen" returns false. Remove this unnecessary comparison. Reviewed-by: Toke Høiland-Jørgensen Acked-by: Daniel Borkmann Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 9b60eda0f727..73fd593d3745 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -364,8 +364,7 @@ static long trie_update_elem(struct bpf_map *map, matchlen = longest_prefix_match(trie, node, key); if (node->prefixlen != matchlen || - node->prefixlen == key->prefixlen || - node->prefixlen == trie->max_prefixlen) + node->prefixlen == key->prefixlen) break; next_bit = extract_bit(key->data, node->prefixlen); From 3d5611b4d7efbefb85a74fcdbc35c603847cc022 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:15 +0800 Subject: [PATCH 2/9] bpf: Remove unnecessary kfree(im_node) in lpm_trie_update_elem MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is no need to call kfree(im_node) when updating element fails, because im_node must be NULL. Remove the unnecessary kfree() for im_node. Reviewed-by: Toke Høiland-Jørgensen Acked-by: Daniel Borkmann Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 73fd593d3745..b5e281a55760 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -315,7 +315,7 @@ static long trie_update_elem(struct bpf_map *map, void *_key, void *value, u64 flags) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); - struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; + struct lpm_trie_node *node, *im_node, *new_node = NULL; struct lpm_trie_node *free_node = NULL; struct lpm_trie_node __rcu **slot; struct bpf_lpm_trie_key_u8 *key = _key; @@ -431,9 +431,7 @@ static long trie_update_elem(struct bpf_map *map, if (ret) { if (new_node) trie->n_entries--; - kfree(new_node); - kfree(im_node); } spin_unlock_irqrestore(&trie->lock, irq_flags); From eae6a075e9537dd69891cf77ca5a88fa8a28b4a1 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:16 +0800 Subject: [PATCH 3/9] bpf: Handle BPF_EXIST and BPF_NOEXIST for LPM trie MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add the currently missing handling for the BPF_EXIST and BPF_NOEXIST flags. These flags can be specified by users and are relevant since LPM trie supports exact matches during update. Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Reviewed-by: Toke Høiland-Jørgensen Acked-by: Daniel Borkmann Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index b5e281a55760..be5bf0389532 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -375,6 +375,10 @@ static long trie_update_elem(struct bpf_map *map, * simply assign the @new_node to that slot and be done. */ if (!node) { + if (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } rcu_assign_pointer(*slot, new_node); goto out; } @@ -383,18 +387,31 @@ static long trie_update_elem(struct bpf_map *map, * which already has the correct data array set. */ if (node->prefixlen == matchlen) { + if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) { + if (flags == BPF_NOEXIST) { + ret = -EEXIST; + goto out; + } + trie->n_entries--; + } else if (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } + new_node->child[0] = node->child[0]; new_node->child[1] = node->child[1]; - if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) - trie->n_entries--; - rcu_assign_pointer(*slot, new_node); free_node = node; goto out; } + if (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } + /* If the new node matches the prefix completely, it must be inserted * as an ancestor. Simply insert it between @node and *@slot. */ From 532d6b36b2bfac5514426a97a4df8d103d700d43 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:17 +0800 Subject: [PATCH 4/9] bpf: Handle in-place update for full LPM trie correctly MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When a LPM trie is full, in-place updates of existing elements incorrectly return -ENOSPC. Fix this by deferring the check of trie->n_entries. For new insertions, n_entries must not exceed max_entries. However, in-place updates are allowed even when the trie is full. Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 44 +++++++++++++++++++++---------------------- 1 file changed, 21 insertions(+), 23 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index be5bf0389532..df6cc0a1c9bf 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -310,6 +310,16 @@ static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, return node; } +static int trie_check_add_elem(struct lpm_trie *trie, u64 flags) +{ + if (flags == BPF_EXIST) + return -ENOENT; + if (trie->n_entries == trie->map.max_entries) + return -ENOSPC; + trie->n_entries++; + return 0; +} + /* Called from syscall or from eBPF program */ static long trie_update_elem(struct bpf_map *map, void *_key, void *value, u64 flags) @@ -333,20 +343,12 @@ static long trie_update_elem(struct bpf_map *map, spin_lock_irqsave(&trie->lock, irq_flags); /* Allocate and fill a new node */ - - if (trie->n_entries == trie->map.max_entries) { - ret = -ENOSPC; - goto out; - } - new_node = lpm_trie_node_alloc(trie, value); if (!new_node) { ret = -ENOMEM; goto out; } - trie->n_entries++; - new_node->prefixlen = key->prefixlen; RCU_INIT_POINTER(new_node->child[0], NULL); RCU_INIT_POINTER(new_node->child[1], NULL); @@ -375,10 +377,10 @@ static long trie_update_elem(struct bpf_map *map, * simply assign the @new_node to that slot and be done. */ if (!node) { - if (flags == BPF_EXIST) { - ret = -ENOENT; + ret = trie_check_add_elem(trie, flags); + if (ret) goto out; - } + rcu_assign_pointer(*slot, new_node); goto out; } @@ -392,10 +394,10 @@ static long trie_update_elem(struct bpf_map *map, ret = -EEXIST; goto out; } - trie->n_entries--; - } else if (flags == BPF_EXIST) { - ret = -ENOENT; - goto out; + } else { + ret = trie_check_add_elem(trie, flags); + if (ret) + goto out; } new_node->child[0] = node->child[0]; @@ -407,10 +409,9 @@ static long trie_update_elem(struct bpf_map *map, goto out; } - if (flags == BPF_EXIST) { - ret = -ENOENT; + ret = trie_check_add_elem(trie, flags); + if (ret) goto out; - } /* If the new node matches the prefix completely, it must be inserted * as an ancestor. Simply insert it between @node and *@slot. @@ -424,6 +425,7 @@ static long trie_update_elem(struct bpf_map *map, im_node = lpm_trie_node_alloc(trie, NULL); if (!im_node) { + trie->n_entries--; ret = -ENOMEM; goto out; } @@ -445,12 +447,8 @@ static long trie_update_elem(struct bpf_map *map, rcu_assign_pointer(*slot, im_node); out: - if (ret) { - if (new_node) - trie->n_entries--; + if (ret) kfree(new_node); - } - spin_unlock_irqrestore(&trie->lock, irq_flags); kfree_rcu(free_node, rcu); From 27abc7b3fa2e09bbe41e2924d328121546865eda Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:18 +0800 Subject: [PATCH 5/9] bpf: Fix exact match conditions in trie_get_next_key() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit trie_get_next_key() uses node->prefixlen == key->prefixlen to identify an exact match, However, it is incorrect because when the target key doesn't fully match the found node (e.g., node->prefixlen != matchlen), these two nodes may also have the same prefixlen. It will return expected result when the passed key exist in the trie. However when a recently-deleted key or nonexistent key is passed to trie_get_next_key(), it may skip keys and return incorrect result. Fix it by using node->prefixlen == matchlen to identify exact matches. When the condition is true after the search, it also implies node->prefixlen equals key->prefixlen, otherwise, the search would return NULL instead. Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map") Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-6-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index df6cc0a1c9bf..9ba6ae145239 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -645,7 +645,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) struct lpm_trie_node **node_stack = NULL; int err = 0, stack_ptr = -1; unsigned int next_bit; - size_t matchlen; + size_t matchlen = 0; /* The get_next_key follows postorder. For the 4 node example in * the top of this file, the trie_get_next_key() returns the following @@ -684,7 +684,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) next_bit = extract_bit(key->data, node->prefixlen); node = rcu_dereference(node->child[next_bit]); } - if (!node || node->prefixlen != key->prefixlen || + if (!node || node->prefixlen != matchlen || (node->flags & LPM_TREE_NODE_FLAG_IM)) goto find_leftmost; From 3d8dc43eb2a3d179809f5fc27c88c93a57ea123d Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:19 +0800 Subject: [PATCH 6/9] bpf: Switch to bpf mem allocator for LPM trie MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Multiple syzbot warnings have been reported. These warnings are mainly about the lock order between trie->lock and kmalloc()'s internal lock. See report [1] as an example: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7-syzkaller-00003-g4376e966ecb7 #0 Not tainted ------------------------------------------------------ syz.3.2069/15008 is trying to acquire lock: ffff88801544e6d8 (&n->list_lock){-.-.}-{2:2}, at: get_partial_node ... but task is already holding lock: ffff88802dcc89f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem ... which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&trie->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave _raw_spin_lock_irqsave+0x3a/0x60 trie_delete_elem+0xb0/0x820 ___bpf_prog_run+0x3e51/0xabd0 __bpf_prog_run32+0xc1/0x100 bpf_dispatcher_nop_func ...... bpf_trace_run2+0x231/0x590 __bpf_trace_contention_end+0xca/0x110 trace_contention_end.constprop.0+0xea/0x170 __pv_queued_spin_lock_slowpath+0x28e/0xcc0 pv_queued_spin_lock_slowpath queued_spin_lock_slowpath queued_spin_lock do_raw_spin_lock+0x210/0x2c0 __raw_spin_lock_irqsave _raw_spin_lock_irqsave+0x42/0x60 __put_partials+0xc3/0x170 qlink_free qlist_free_all+0x4e/0x140 kasan_quarantine_reduce+0x192/0x1e0 __kasan_slab_alloc+0x69/0x90 kasan_slab_alloc slab_post_alloc_hook slab_alloc_node kmem_cache_alloc_node_noprof+0x153/0x310 __alloc_skb+0x2b1/0x380 ...... -> #0 (&n->list_lock){-.-.}-{2:2}: check_prev_add check_prevs_add validate_chain __lock_acquire+0x2478/0x3b30 lock_acquire lock_acquire+0x1b1/0x560 __raw_spin_lock_irqsave _raw_spin_lock_irqsave+0x3a/0x60 get_partial_node.part.0+0x20/0x350 get_partial_node get_partial ___slab_alloc+0x65b/0x1870 __slab_alloc.constprop.0+0x56/0xb0 __slab_alloc_node slab_alloc_node __do_kmalloc_node __kmalloc_node_noprof+0x35c/0x440 kmalloc_node_noprof bpf_map_kmalloc_node+0x98/0x4a0 lpm_trie_node_alloc trie_update_elem+0x1ef/0xe00 bpf_map_update_value+0x2c1/0x6c0 map_update_elem+0x623/0x910 __sys_bpf+0x90c/0x49a0 ... other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&trie->lock); lock(&n->list_lock); lock(&trie->lock); lock(&n->list_lock); *** DEADLOCK *** [1]: https://syzkaller.appspot.com/bug?extid=9045c0a3d5a7f1b119f7 A bpf program attached to trace_contention_end() triggers after acquiring &n->list_lock. The program invokes trie_delete_elem(), which then acquires trie->lock. However, it is possible that another process is invoking trie_update_elem(). trie_update_elem() will acquire trie->lock first, then invoke kmalloc_node(). kmalloc_node() may invoke get_partial_node() and try to acquire &n->list_lock (not necessarily the same lock object). Therefore, lockdep warns about the circular locking dependency. Invoking kmalloc() before acquiring trie->lock could fix the warning. However, since BPF programs call be invoked from any context (e.g., through kprobe/tracepoint/fentry), there may still be lock ordering problems for internal locks in kmalloc() or trie->lock itself. To eliminate these potential lock ordering problems with kmalloc()'s internal locks, replacing kmalloc()/kfree()/kfree_rcu() with equivalent BPF memory allocator APIs that can be invoked in any context. The lock ordering problems with trie->lock (e.g., reentrance) will be handled separately. Three aspects of this change require explanation: 1. Intermediate and leaf nodes are allocated from the same allocator. Since the value size of LPM trie is usually small, using a single alocator reduces the memory overhead of the BPF memory allocator. 2. Leaf nodes are allocated before disabling IRQs. This handles cases where leaf_size is large (e.g., > 4KB - 8) and updates require intermediate node allocation. If leaf nodes were allocated in IRQ-disabled region, the free objects in BPF memory allocator would not be refilled timely and the intermediate node allocation may fail. 3. Paired migrate_{disable|enable}() calls for node alloc and free. The BPF memory allocator uses per-CPU struct internally, these paired calls are necessary to guarantee correctness. Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-7-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 71 +++++++++++++++++++++++++++++-------------- 1 file changed, 48 insertions(+), 23 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 9ba6ae145239..f850360e75ce 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -15,6 +15,7 @@ #include #include #include +#include /* Intermediate node */ #define LPM_TREE_NODE_FLAG_IM BIT(0) @@ -22,7 +23,6 @@ struct lpm_trie_node; struct lpm_trie_node { - struct rcu_head rcu; struct lpm_trie_node __rcu *child[2]; u32 prefixlen; u32 flags; @@ -32,6 +32,7 @@ struct lpm_trie_node { struct lpm_trie { struct bpf_map map; struct lpm_trie_node __rcu *root; + struct bpf_mem_alloc ma; size_t n_entries; size_t max_prefixlen; size_t data_size; @@ -287,17 +288,18 @@ static void *trie_lookup_elem(struct bpf_map *map, void *_key) return found->data + trie->data_size; } -static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, - const void *value) +static struct lpm_trie_node *lpm_trie_node_alloc(struct lpm_trie *trie, + const void *value, + bool disable_migration) { struct lpm_trie_node *node; - size_t size = sizeof(struct lpm_trie_node) + trie->data_size; - if (value) - size += trie->map.value_size; + if (disable_migration) + migrate_disable(); + node = bpf_mem_cache_alloc(&trie->ma); + if (disable_migration) + migrate_enable(); - node = bpf_map_kmalloc_node(&trie->map, size, GFP_NOWAIT | __GFP_NOWARN, - trie->map.numa_node); if (!node) return NULL; @@ -325,7 +327,7 @@ static long trie_update_elem(struct bpf_map *map, void *_key, void *value, u64 flags) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); - struct lpm_trie_node *node, *im_node, *new_node = NULL; + struct lpm_trie_node *node, *im_node, *new_node; struct lpm_trie_node *free_node = NULL; struct lpm_trie_node __rcu **slot; struct bpf_lpm_trie_key_u8 *key = _key; @@ -340,14 +342,14 @@ static long trie_update_elem(struct bpf_map *map, if (key->prefixlen > trie->max_prefixlen) return -EINVAL; - spin_lock_irqsave(&trie->lock, irq_flags); + /* Allocate and fill a new node. Need to disable migration before + * invoking bpf_mem_cache_alloc(). + */ + new_node = lpm_trie_node_alloc(trie, value, true); + if (!new_node) + return -ENOMEM; - /* Allocate and fill a new node */ - new_node = lpm_trie_node_alloc(trie, value); - if (!new_node) { - ret = -ENOMEM; - goto out; - } + spin_lock_irqsave(&trie->lock, irq_flags); new_node->prefixlen = key->prefixlen; RCU_INIT_POINTER(new_node->child[0], NULL); @@ -423,7 +425,8 @@ static long trie_update_elem(struct bpf_map *map, goto out; } - im_node = lpm_trie_node_alloc(trie, NULL); + /* migration is disabled within the locked scope */ + im_node = lpm_trie_node_alloc(trie, NULL, false); if (!im_node) { trie->n_entries--; ret = -ENOMEM; @@ -447,10 +450,13 @@ static long trie_update_elem(struct bpf_map *map, rcu_assign_pointer(*slot, im_node); out: - if (ret) - kfree(new_node); spin_unlock_irqrestore(&trie->lock, irq_flags); - kfree_rcu(free_node, rcu); + + migrate_disable(); + if (ret) + bpf_mem_cache_free(&trie->ma, new_node); + bpf_mem_cache_free_rcu(&trie->ma, free_node); + migrate_enable(); return ret; } @@ -548,8 +554,11 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) out: spin_unlock_irqrestore(&trie->lock, irq_flags); - kfree_rcu(free_parent, rcu); - kfree_rcu(free_node, rcu); + + migrate_disable(); + bpf_mem_cache_free_rcu(&trie->ma, free_parent); + bpf_mem_cache_free_rcu(&trie->ma, free_node); + migrate_enable(); return ret; } @@ -571,6 +580,8 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) static struct bpf_map *trie_alloc(union bpf_attr *attr) { struct lpm_trie *trie; + size_t leaf_size; + int err; /* check sanity of attributes */ if (attr->max_entries == 0 || @@ -595,7 +606,17 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr) spin_lock_init(&trie->lock); + /* Allocate intermediate and leaf nodes from the same allocator */ + leaf_size = sizeof(struct lpm_trie_node) + trie->data_size + + trie->map.value_size; + err = bpf_mem_alloc_init(&trie->ma, leaf_size, false); + if (err) + goto free_out; return &trie->map; + +free_out: + bpf_map_area_free(trie); + return ERR_PTR(err); } static void trie_free(struct bpf_map *map) @@ -627,13 +648,17 @@ static void trie_free(struct bpf_map *map) continue; } - kfree(node); + /* No bpf program may access the map, so freeing the + * node without waiting for the extra RCU GP. + */ + bpf_mem_cache_raw_free(node); RCU_INIT_POINTER(*slot, NULL); break; } } out: + bpf_mem_alloc_destroy(&trie->ma); bpf_map_area_free(trie); } From 6a5c63d43c0216d64915baa0e0eacf2beb66b271 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:20 +0800 Subject: [PATCH 7/9] bpf: Use raw_spinlock_t for LPM trie After switching from kmalloc() to the bpf memory allocator, there will be no blocking operation during the update of LPM trie. Therefore, change trie->lock from spinlock_t to raw_spinlock_t to make LPM trie usable in atomic context, even on RT kernels. The max value of prefixlen is 2048. Therefore, update or deletion operations will find the target after at most 2048 comparisons. Constructing a test case which updates an element after 2048 comparisons under a 8 CPU VM, and the average time and the maximal time for such update operation is about 210us and 900us. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-8-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index f850360e75ce..f8bc1e096182 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -36,7 +36,7 @@ struct lpm_trie { size_t n_entries; size_t max_prefixlen; size_t data_size; - spinlock_t lock; + raw_spinlock_t lock; }; /* This trie implements a longest prefix match algorithm that can be used to @@ -349,7 +349,7 @@ static long trie_update_elem(struct bpf_map *map, if (!new_node) return -ENOMEM; - spin_lock_irqsave(&trie->lock, irq_flags); + raw_spin_lock_irqsave(&trie->lock, irq_flags); new_node->prefixlen = key->prefixlen; RCU_INIT_POINTER(new_node->child[0], NULL); @@ -450,7 +450,7 @@ static long trie_update_elem(struct bpf_map *map, rcu_assign_pointer(*slot, im_node); out: - spin_unlock_irqrestore(&trie->lock, irq_flags); + raw_spin_unlock_irqrestore(&trie->lock, irq_flags); migrate_disable(); if (ret) @@ -477,7 +477,7 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) if (key->prefixlen > trie->max_prefixlen) return -EINVAL; - spin_lock_irqsave(&trie->lock, irq_flags); + raw_spin_lock_irqsave(&trie->lock, irq_flags); /* Walk the tree looking for an exact key/length match and keeping * track of the path we traverse. We will need to know the node @@ -553,7 +553,7 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) free_node = node; out: - spin_unlock_irqrestore(&trie->lock, irq_flags); + raw_spin_unlock_irqrestore(&trie->lock, irq_flags); migrate_disable(); bpf_mem_cache_free_rcu(&trie->ma, free_parent); @@ -604,7 +604,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr) offsetof(struct bpf_lpm_trie_key_u8, data); trie->max_prefixlen = trie->data_size * 8; - spin_lock_init(&trie->lock); + raw_spin_lock_init(&trie->lock); /* Allocate intermediate and leaf nodes from the same allocator */ leaf_size = sizeof(struct lpm_trie_node) + trie->data_size + From 3e18f5f1e5a152a51dbb6c234e2a0421aec11e31 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:21 +0800 Subject: [PATCH 8/9] selftests/bpf: Move test_lpm_map.c to map_tests Move test_lpm_map.c to map_tests/ to include LPM trie test cases in regular test_maps run. Most code remains unchanged, including the use of assert(). Only reduce n_lookups from 64K to 512, which decreases test_lpm_map runtime from 37s to 0.7s. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-9-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/.gitignore | 1 - tools/testing/selftests/bpf/Makefile | 2 +- .../lpm_trie_map_basic_ops.c} | 10 +++------- 3 files changed, 4 insertions(+), 9 deletions(-) rename tools/testing/selftests/bpf/{test_lpm_map.c => map_tests/lpm_trie_map_basic_ops.c} (99%) diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index c2a1842c3d8b..e9c377001f93 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -5,7 +5,6 @@ bpf-syscall* test_verifier test_maps test_lru_map -test_lpm_map test_tag FEATURE-DUMP.libbpf FEATURE-DUMP.selftests diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 6ad3b1ba1920..7eeb3cbe18c7 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -83,7 +83,7 @@ CLANG_CPUV4 := 1 endif # Order correspond to 'make run_tests' order -TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \ +TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_progs \ test_sockmap \ test_tcpnotify_user test_sysctl \ test_progs-no_alu32 diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c similarity index 99% rename from tools/testing/selftests/bpf/test_lpm_map.c rename to tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c index d98c72dc563e..f375c89d78a4 100644 --- a/tools/testing/selftests/bpf/test_lpm_map.c +++ b/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c @@ -223,7 +223,7 @@ static void test_lpm_map(int keysize) n_matches = 0; n_matches_after_delete = 0; n_nodes = 1 << 8; - n_lookups = 1 << 16; + n_lookups = 1 << 9; data = alloca(keysize); memset(data, 0, keysize); @@ -770,16 +770,13 @@ static void test_lpm_multi_thread(void) close(map_fd); } -int main(void) +void test_lpm_trie_map_basic_ops(void) { int i; /* we want predictable, pseudo random tests */ srand(0xf00ba1); - /* Use libbpf 1.0 API mode */ - libbpf_set_strict_mode(LIBBPF_STRICT_ALL); - test_lpm_basic(); test_lpm_order(); @@ -792,6 +789,5 @@ int main(void) test_lpm_get_next_key(); test_lpm_multi_thread(); - printf("test_lpm: OK\n"); - return 0; + printf("%s: PASS\n", __func__); } From 04d4ce91b0bed4120e0c5fadc5291cebaa9c2a06 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 6 Dec 2024 19:06:22 +0800 Subject: [PATCH 9/9] selftests/bpf: Add more test cases for LPM trie Add more test cases for LPM trie in test_maps: 1) test_lpm_trie_update_flags It constructs various use cases for BPF_EXIST and BPF_NOEXIST and check whether the return value of update operation is expected. 2) test_lpm_trie_update_full_maps It tests the update operations on a full LPM trie map. Adding new node will fail and overwriting the value of existed node will succeed. 3) test_lpm_trie_iterate_strs and test_lpm_trie_iterate_ints There two test cases test whether the iteration through get_next_key is sorted and expected. These two test cases delete the minimal key after each iteration and check whether next iteration returns the second minimal key. The only difference between these two test cases is the former one saves strings in the LPM trie and the latter saves integers. Without the fix of get_next_key, these two cases will fail as shown below: test_lpm_trie_iterate_strs(1091):FAIL:iterate #2 got abc exp abS test_lpm_trie_iterate_ints(1142):FAIL:iterate #1 got 0x2 exp 0x1 Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-10-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- .../bpf/map_tests/lpm_trie_map_basic_ops.c | 395 ++++++++++++++++++ 1 file changed, 395 insertions(+) diff --git a/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c b/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c index f375c89d78a4..d32e4edac930 100644 --- a/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c +++ b/tools/testing/selftests/bpf/map_tests/lpm_trie_map_basic_ops.c @@ -20,10 +20,12 @@ #include #include #include +#include #include #include #include +#include #include "bpf_util.h" @@ -33,6 +35,22 @@ struct tlpm_node { uint8_t key[]; }; +struct lpm_trie_bytes_key { + union { + struct bpf_lpm_trie_key_hdr hdr; + __u32 prefixlen; + }; + unsigned char data[8]; +}; + +struct lpm_trie_int_key { + union { + struct bpf_lpm_trie_key_hdr hdr; + __u32 prefixlen; + }; + unsigned int data; +}; + static struct tlpm_node *tlpm_match(struct tlpm_node *list, const uint8_t *key, size_t n_bits); @@ -770,6 +788,378 @@ static void test_lpm_multi_thread(void) close(map_fd); } +static int lpm_trie_create(unsigned int key_size, unsigned int value_size, unsigned int max_entries) +{ + LIBBPF_OPTS(bpf_map_create_opts, opts); + int fd; + + opts.map_flags = BPF_F_NO_PREALLOC; + fd = bpf_map_create(BPF_MAP_TYPE_LPM_TRIE, "lpm_trie", key_size, value_size, max_entries, + &opts); + CHECK(fd < 0, "bpf_map_create", "error %d\n", errno); + + return fd; +} + +static void test_lpm_trie_update_flags(void) +{ + struct lpm_trie_int_key key; + unsigned int value, got; + int fd, err; + + fd = lpm_trie_create(sizeof(key), sizeof(value), 3); + + /* invalid flags (Error) */ + key.prefixlen = 32; + key.data = 0; + value = 0; + err = bpf_map_update_elem(fd, &key, &value, BPF_F_LOCK); + CHECK(err != -EINVAL, "invalid update flag", "error %d\n", err); + + /* invalid flags (Error) */ + key.prefixlen = 32; + key.data = 0; + value = 0; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST | BPF_EXIST); + CHECK(err != -EINVAL, "invalid update flag", "error %d\n", err); + + /* overwrite an empty qp-trie (Error) */ + key.prefixlen = 32; + key.data = 0; + value = 2; + err = bpf_map_update_elem(fd, &key, &value, BPF_EXIST); + CHECK(err != -ENOENT, "overwrite empty qp-trie", "error %d\n", err); + + /* add a new node */ + key.prefixlen = 16; + key.data = 0; + value = 1; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* add the same node as new node (Error) */ + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err != -EEXIST, "add new elem again", "error %d\n", err); + + /* overwrite the existed node */ + value = 4; + err = bpf_map_update_elem(fd, &key, &value, BPF_EXIST); + CHECK(err, "overwrite elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* overwrite the node */ + value = 1; + err = bpf_map_update_elem(fd, &key, &value, BPF_ANY); + CHECK(err, "update elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* overwrite a non-existent node which is the prefix of the first + * node (Error). + */ + key.prefixlen = 8; + key.data = 0; + value = 2; + err = bpf_map_update_elem(fd, &key, &value, BPF_EXIST); + CHECK(err != -ENOENT, "overwrite nonexistent elem", "error %d\n", err); + + /* add a new node which is the prefix of the first node */ + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup key", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* add another new node which will be the sibling of the first node */ + key.prefixlen = 9; + key.data = htobe32(1 << 23); + value = 5; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup key", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* overwrite the third node */ + value = 3; + err = bpf_map_update_elem(fd, &key, &value, BPF_ANY); + CHECK(err, "overwrite elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup key", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* delete the second node to make it an intermediate node */ + key.prefixlen = 8; + key.data = 0; + err = bpf_map_delete_elem(fd, &key); + CHECK(err, "del elem", "error %d\n", err); + + /* overwrite the intermediate node (Error) */ + value = 2; + err = bpf_map_update_elem(fd, &key, &value, BPF_EXIST); + CHECK(err != -ENOENT, "overwrite nonexistent elem", "error %d\n", err); + + close(fd); +} + +static void test_lpm_trie_update_full_map(void) +{ + struct lpm_trie_int_key key; + int value, got; + int fd, err; + + fd = lpm_trie_create(sizeof(key), sizeof(value), 3); + + /* add a new node */ + key.prefixlen = 16; + key.data = 0; + value = 0; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* add new node */ + key.prefixlen = 8; + key.data = 0; + value = 1; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* add new node */ + key.prefixlen = 9; + key.data = htobe32(1 << 23); + value = 2; + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add new elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* try to add more node (Error) */ + key.prefixlen = 32; + key.data = 0; + value = 3; + err = bpf_map_update_elem(fd, &key, &value, BPF_ANY); + CHECK(err != -ENOSPC, "add to full trie", "error %d\n", err); + + /* update the value of an existed node with BPF_EXIST */ + key.prefixlen = 16; + key.data = 0; + value = 4; + err = bpf_map_update_elem(fd, &key, &value, BPF_EXIST); + CHECK(err, "overwrite elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + /* update the value of an existed node with BPF_ANY */ + key.prefixlen = 9; + key.data = htobe32(1 << 23); + value = 5; + err = bpf_map_update_elem(fd, &key, &value, BPF_ANY); + CHECK(err, "overwrite elem", "error %d\n", err); + got = 0; + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "error %d\n", err); + CHECK(got != value, "check value", "got %d exp %d\n", got, value); + + close(fd); +} + +static int cmp_str(const void *a, const void *b) +{ + const char *str_a = *(const char **)a, *str_b = *(const char **)b; + + return strcmp(str_a, str_b); +} + +/* Save strings in LPM trie. The trailing '\0' for each string will be + * accounted in the prefixlen. The strings returned during the iteration + * should be sorted as expected. + */ +static void test_lpm_trie_iterate_strs(void) +{ + static const char * const keys[] = { + "ab", "abO", "abc", "abo", "abS", "abcd", + }; + const char *sorted_keys[ARRAY_SIZE(keys)]; + struct lpm_trie_bytes_key key, next_key; + unsigned int value, got, i, j, len; + struct lpm_trie_bytes_key *cur; + int fd, err; + + fd = lpm_trie_create(sizeof(key), sizeof(value), ARRAY_SIZE(keys)); + + for (i = 0; i < ARRAY_SIZE(keys); i++) { + unsigned int flags; + + /* add i-th element */ + flags = i % 2 ? BPF_NOEXIST : 0; + len = strlen(keys[i]); + /* include the trailing '\0' */ + key.prefixlen = (len + 1) * 8; + memset(key.data, 0, sizeof(key.data)); + memcpy(key.data, keys[i], len); + value = i + 100; + err = bpf_map_update_elem(fd, &key, &value, flags); + CHECK(err, "add elem", "#%u error %d\n", i, err); + + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "#%u error %d\n", i, err); + CHECK(got != value, "lookup elem", "#%u expect %u got %u\n", i, value, got); + + /* re-add i-th element (Error) */ + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err != -EEXIST, "re-add elem", "#%u error %d\n", i, err); + + /* Overwrite i-th element */ + flags = i % 2 ? 0 : BPF_EXIST; + value = i; + err = bpf_map_update_elem(fd, &key, &value, flags); + CHECK(err, "update elem", "error %d\n", err); + + /* Lookup #[0~i] elements */ + for (j = 0; j <= i; j++) { + len = strlen(keys[j]); + key.prefixlen = (len + 1) * 8; + memset(key.data, 0, sizeof(key.data)); + memcpy(key.data, keys[j], len); + err = bpf_map_lookup_elem(fd, &key, &got); + CHECK(err, "lookup elem", "#%u/%u error %d\n", i, j, err); + CHECK(got != j, "lookup elem", "#%u/%u expect %u got %u\n", + i, j, value, got); + } + } + + /* Add element to a full qp-trie (Error) */ + key.prefixlen = sizeof(key.data) * 8; + memset(key.data, 0, sizeof(key.data)); + value = 0; + err = bpf_map_update_elem(fd, &key, &value, 0); + CHECK(err != -ENOSPC, "add to full qp-trie", "error %d\n", err); + + /* Iterate sorted elements: no deletion */ + memcpy(sorted_keys, keys, sizeof(keys)); + qsort(sorted_keys, ARRAY_SIZE(sorted_keys), sizeof(sorted_keys[0]), cmp_str); + cur = NULL; + for (i = 0; i < ARRAY_SIZE(sorted_keys); i++) { + len = strlen(sorted_keys[i]); + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err, "iterate", "#%u error %d\n", i, err); + CHECK(next_key.prefixlen != (len + 1) * 8, "iterate", + "#%u invalid len %u expect %u\n", + i, next_key.prefixlen, (len + 1) * 8); + CHECK(memcmp(sorted_keys[i], next_key.data, len + 1), "iterate", + "#%u got %.*s exp %.*s\n", i, len, next_key.data, len, sorted_keys[i]); + + cur = &next_key; + } + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err != -ENOENT, "more element", "error %d\n", err); + + /* Iterate sorted elements: delete the found key after each iteration */ + cur = NULL; + for (i = 0; i < ARRAY_SIZE(sorted_keys); i++) { + len = strlen(sorted_keys[i]); + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err, "iterate", "#%u error %d\n", i, err); + CHECK(next_key.prefixlen != (len + 1) * 8, "iterate", + "#%u invalid len %u expect %u\n", + i, next_key.prefixlen, (len + 1) * 8); + CHECK(memcmp(sorted_keys[i], next_key.data, len + 1), "iterate", + "#%u got %.*s exp %.*s\n", i, len, next_key.data, len, sorted_keys[i]); + + cur = &next_key; + + err = bpf_map_delete_elem(fd, cur); + CHECK(err, "delete", "#%u error %d\n", i, err); + } + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err != -ENOENT, "non-empty qp-trie", "error %d\n", err); + + close(fd); +} + +/* Use the fixed prefixlen (32) and save integers in LPM trie. The iteration of + * LPM trie will return these integers in big-endian order, therefore, convert + * these integers to big-endian before update. After each iteration, delete the + * found key (the smallest integer) and expect the next iteration will return + * the second smallest number. + */ +static void test_lpm_trie_iterate_ints(void) +{ + struct lpm_trie_int_key key, next_key; + unsigned int i, max_entries; + struct lpm_trie_int_key *cur; + unsigned int *data_set; + int fd, err; + bool value; + + max_entries = 4096; + data_set = calloc(max_entries, sizeof(*data_set)); + CHECK(!data_set, "malloc", "no mem\n"); + for (i = 0; i < max_entries; i++) + data_set[i] = i; + + fd = lpm_trie_create(sizeof(key), sizeof(value), max_entries); + value = true; + for (i = 0; i < max_entries; i++) { + key.prefixlen = 32; + key.data = htobe32(data_set[i]); + + err = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST); + CHECK(err, "add elem", "#%u error %d\n", i, err); + } + + cur = NULL; + for (i = 0; i < max_entries; i++) { + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err, "iterate", "#%u error %d\n", i, err); + CHECK(next_key.prefixlen != 32, "iterate", "#%u invalid len %u\n", + i, next_key.prefixlen); + CHECK(be32toh(next_key.data) != data_set[i], "iterate", "#%u got 0x%x exp 0x%x\n", + i, be32toh(next_key.data), data_set[i]); + cur = &next_key; + + /* + * Delete the minimal key, the next call of bpf_get_next_key() + * will return the second minimal key. + */ + err = bpf_map_delete_elem(fd, &next_key); + CHECK(err, "del elem", "#%u elem error %d\n", i, err); + } + err = bpf_map_get_next_key(fd, cur, &next_key); + CHECK(err != -ENOENT, "more element", "error %d\n", err); + + err = bpf_map_get_next_key(fd, NULL, &next_key); + CHECK(err != -ENOENT, "no-empty qp-trie", "error %d\n", err); + + free(data_set); + + close(fd); +} + void test_lpm_trie_map_basic_ops(void) { int i; @@ -789,5 +1179,10 @@ void test_lpm_trie_map_basic_ops(void) test_lpm_get_next_key(); test_lpm_multi_thread(); + test_lpm_trie_update_flags(); + test_lpm_trie_update_full_map(); + test_lpm_trie_iterate_strs(); + test_lpm_trie_iterate_ints(); + printf("%s: PASS\n", __func__); }