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1// SPDX-License-Identifier: GPL-2.0-only2// Copyright (C) 2022-2023 Isovalent, Inc.3digraph {4 node [colorscheme=accent4,style=filled] # Apply colorscheme to all nodes5 graph [splines=ortho, nodesep=1]6 7 subgraph cluster_key {8 label = "Key\n(locks held during operation)";9 rankdir = TB;10 11 remote_lock [shape=rectangle,fillcolor=4,label="remote CPU LRU lock"]12 hash_lock [shape=rectangle,fillcolor=3,label="hashtab lock"]13 lru_lock [shape=rectangle,fillcolor=2,label="LRU lock"]14 local_lock [shape=rectangle,fillcolor=1,label="local CPU LRU lock"]15 no_lock [shape=rectangle,label="no locks held"]16 }17 18 begin [shape=oval,label="begin\nbpf_map_update()"]19 20 // Nodes below with an 'fn_' prefix are roughly labeled by the C function21 // names that initiate the corresponding logic in kernel/bpf/bpf_lru_list.c.22 // Number suffixes and errno suffixes handle subsections of the corresponding23 // logic in the function as of the writing of this dot.24 25 // cf. __local_list_pop_free() / bpf_percpu_lru_pop_free()26 local_freelist_check [shape=diamond,fillcolor=1,27 label="Local freelist\nnode available?"];28 use_local_node [shape=rectangle,29 label="Use node owned\nby this CPU"]30 31 // cf. bpf_lru_pop_free()32 common_lru_check [shape=diamond,33 label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];34 35 fn_bpf_lru_list_pop_free_to_local [shape=rectangle,fillcolor=2,36 label="Flush local pending,37 Rotate Global list, move38 LOCAL_FREE_TARGET39 from global -> local"]40 // Also corresponds to:41 // fn__local_list_flush()42 // fn_bpf_lru_list_rotate()43 fn___bpf_lru_node_move_to_free[shape=diamond,fillcolor=2,44 label="Able to free\nLOCAL_FREE_TARGET\nnodes?"]45 46 fn___bpf_lru_list_shrink_inactive [shape=rectangle,fillcolor=3,47 label="Shrink inactive list48 up to remaining49 LOCAL_FREE_TARGET50 (global LRU -> local)"]51 fn___bpf_lru_list_shrink [shape=diamond,fillcolor=2,52 label="> 0 entries in\nlocal free list?"]53 fn___bpf_lru_list_shrink2 [shape=rectangle,fillcolor=2,54 label="Steal one node from55 inactive, or if empty,56 from active global list"]57 fn___bpf_lru_list_shrink3 [shape=rectangle,fillcolor=3,58 label="Try to remove\nnode from hashtab"]59 60 local_freelist_check2 [shape=diamond,label="Htab removal\nsuccessful?"]61 common_lru_check2 [shape=diamond,62 label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];63 64 subgraph cluster_remote_lock {65 label = "Iterate through CPUs\n(start from current)";66 style = dashed;67 rankdir=LR;68 69 local_freelist_check5 [shape=diamond,fillcolor=4,70 label="Steal a node from\nper-cpu freelist?"]71 local_freelist_check6 [shape=rectangle,fillcolor=4,72 label="Steal a node from73 (1) Unreferenced pending, or74 (2) Any pending node"]75 local_freelist_check7 [shape=rectangle,fillcolor=3,76 label="Try to remove\nnode from hashtab"]77 fn_htab_lru_map_update_elem [shape=diamond,78 label="Stole node\nfrom remote\nCPU?"]79 fn_htab_lru_map_update_elem2 [shape=diamond,label="Iterated\nall CPUs?"]80 // Also corresponds to:81 // use_local_node()82 // fn__local_list_pop_pending()83 }84 85 fn_bpf_lru_list_pop_free_to_local2 [shape=rectangle,86 label="Use node that was\nnot recently referenced"]87 local_freelist_check4 [shape=rectangle,88 label="Use node that was\nactively referenced\nin global list"]89 fn_htab_lru_map_update_elem_ENOMEM [shape=oval,label="return -ENOMEM"]90 fn_htab_lru_map_update_elem3 [shape=rectangle,91 label="Use node that was\nactively referenced\nin (another?) CPU's cache"]92 fn_htab_lru_map_update_elem4 [shape=rectangle,fillcolor=3,93 label="Update hashmap\nwith new element"]94 fn_htab_lru_map_update_elem5 [shape=oval,label="return 0"]95 fn_htab_lru_map_update_elem_EBUSY [shape=oval,label="return -EBUSY"]96 fn_htab_lru_map_update_elem_EEXIST [shape=oval,label="return -EEXIST"]97 fn_htab_lru_map_update_elem_ENOENT [shape=oval,label="return -ENOENT"]98 99 begin -> local_freelist_check100 local_freelist_check -> use_local_node [xlabel="Y"]101 local_freelist_check -> common_lru_check [xlabel="N"]102 common_lru_check -> fn_bpf_lru_list_pop_free_to_local [xlabel="Y"]103 common_lru_check -> fn___bpf_lru_list_shrink_inactive [xlabel="N"]104 fn_bpf_lru_list_pop_free_to_local -> fn___bpf_lru_node_move_to_free105 fn___bpf_lru_node_move_to_free ->106 fn_bpf_lru_list_pop_free_to_local2 [xlabel="Y"]107 fn___bpf_lru_node_move_to_free ->108 fn___bpf_lru_list_shrink_inactive [xlabel="N"]109 fn___bpf_lru_list_shrink_inactive -> fn___bpf_lru_list_shrink110 fn___bpf_lru_list_shrink -> fn_bpf_lru_list_pop_free_to_local2 [xlabel = "Y"]111 fn___bpf_lru_list_shrink -> fn___bpf_lru_list_shrink2 [xlabel="N"]112 fn___bpf_lru_list_shrink2 -> fn___bpf_lru_list_shrink3113 fn___bpf_lru_list_shrink3 -> local_freelist_check2114 local_freelist_check2 -> local_freelist_check4 [xlabel = "Y"]115 local_freelist_check2 -> common_lru_check2 [xlabel = "N"]116 common_lru_check2 -> local_freelist_check5 [xlabel = "Y"]117 common_lru_check2 -> fn_htab_lru_map_update_elem_ENOMEM [xlabel = "N"]118 local_freelist_check5 -> fn_htab_lru_map_update_elem [xlabel = "Y"]119 local_freelist_check5 -> local_freelist_check6 [xlabel = "N"]120 local_freelist_check6 -> local_freelist_check7121 local_freelist_check7 -> fn_htab_lru_map_update_elem122 123 fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem3 [xlabel = "Y"]124 fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem2 [xlabel = "N"]125 fn_htab_lru_map_update_elem2 ->126 fn_htab_lru_map_update_elem_ENOMEM [xlabel = "Y"]127 fn_htab_lru_map_update_elem2 -> local_freelist_check5 [xlabel = "N"]128 fn_htab_lru_map_update_elem3 -> fn_htab_lru_map_update_elem4129 130 use_local_node -> fn_htab_lru_map_update_elem4131 fn_bpf_lru_list_pop_free_to_local2 -> fn_htab_lru_map_update_elem4132 local_freelist_check4 -> fn_htab_lru_map_update_elem4133 134 fn_htab_lru_map_update_elem4 -> fn_htab_lru_map_update_elem5 [headlabel="Success"]135 fn_htab_lru_map_update_elem4 ->136 fn_htab_lru_map_update_elem_EBUSY [xlabel="Hashtab lock failed"]137 fn_htab_lru_map_update_elem4 ->138 fn_htab_lru_map_update_elem_EEXIST [xlabel="BPF_EXIST set and\nkey already exists"]139 fn_htab_lru_map_update_elem4 ->140 fn_htab_lru_map_update_elem_ENOENT [headlabel="BPF_NOEXIST set\nand no such entry"]141 142 // Create invisible pad nodes to line up various nodes143 pad0 [style=invis]144 pad1 [style=invis]145 pad2 [style=invis]146 pad3 [style=invis]147 pad4 [style=invis]148 149 // Line up the key with the top of the graph150 no_lock -> local_lock [style=invis]151 local_lock -> lru_lock [style=invis]152 lru_lock -> hash_lock [style=invis]153 hash_lock -> remote_lock [style=invis]154 remote_lock -> local_freelist_check5 [style=invis]155 remote_lock -> fn___bpf_lru_list_shrink [style=invis]156 157 // Line up return code nodes at the bottom of the graph158 fn_htab_lru_map_update_elem -> pad0 [style=invis]159 pad0 -> pad1 [style=invis]160 pad1 -> pad2 [style=invis]161 //pad2-> fn_htab_lru_map_update_elem_ENOMEM [style=invis]162 fn_htab_lru_map_update_elem4 -> pad3 [style=invis]163 pad3 -> fn_htab_lru_map_update_elem5 [style=invis]164 pad3 -> fn_htab_lru_map_update_elem_EBUSY [style=invis]165 pad3 -> fn_htab_lru_map_update_elem_EEXIST [style=invis]166 pad3 -> fn_htab_lru_map_update_elem_ENOENT [style=invis]167 168 // Reduce diagram width by forcing some nodes to appear above others169 local_freelist_check4 -> fn_htab_lru_map_update_elem3 [style=invis]170 common_lru_check2 -> pad4 [style=invis]171 pad4 -> local_freelist_check5 [style=invis]172}173