Thread (11 messages) read the whole thread 11 messages, 2 authors, 2018-12-29
STALE2773d REVIEWED: 1 (0M)

Revision v1 of 158 in this series; 1 review trailer.

Revisions (158)
  1. v1 [diff vs current]
  2. v1 [diff vs current]
  3. v1 [diff vs current]
  4. v1 [diff vs current]
  5. v1 [diff vs current]
  6. v1 [diff vs current]
  7. v1 [diff vs current]
  8. v1 [diff vs current]
  9. v1 [diff vs current]
  10. v1 [diff vs current]
  11. v1 [diff vs current]
  12. v1 [diff vs current]
  13. v1 [diff vs current]
  14. v1 [diff vs current]
  15. v1 [diff vs current]
  16. v1 [diff vs current]
  17. v1 [diff vs current]
  18. v1 [diff vs current]
  19. v1 [diff vs current]
  20. v1 [diff vs current]
  21. v1 [diff vs current]
  22. v1 [diff vs current]
  23. v1 [diff vs current]
  24. v1 [diff vs current]
  25. v1 [diff vs current]
  26. v1 [diff vs current]
  27. v1 [diff vs current]
  28. v1 [diff vs current]
  29. v1 [diff vs current]
  30. v1 [diff vs current]
  31. v1 [diff vs current]
  32. v1 [diff vs current]
  33. v1 [diff vs current]
  34. v1 [diff vs current]
  35. v1 [diff vs current]
  36. v1 [diff vs current]
  37. v1 [diff vs current]
  38. v1 [diff vs current]
  39. v1 [diff vs current]
  40. v1 [diff vs current]
  41. v1 [diff vs current]
  42. v1 [diff vs current]
  43. v1 [diff vs current]
  44. v1 [diff vs current]
  45. v1 [diff vs current]
  46. v1 [diff vs current]
  47. v1 [diff vs current]
  48. v1 current
  49. v1 [diff vs current]
  50. v1 [diff vs current]
  51. v1 [diff vs current]
  52. v1 [diff vs current]
  53. v1 [diff vs current]
  54. v1 [diff vs current]
  55. v1 [diff vs current]
  56. v1 [diff vs current]
  57. v1 [diff vs current]
  58. v1 [diff vs current]
  59. v1 [diff vs current]
  60. v1 [diff vs current]
  61. v1 [diff vs current]
  62. v1 [diff vs current]
  63. v1 [diff vs current]
  64. v1 [diff vs current]
  65. v1 [diff vs current]
  66. v1 [diff vs current]
  67. v1 [diff vs current]
  68. v1 [diff vs current]
  69. v1 [diff vs current]
  70. v1 [diff vs current]
  71. v1 [diff vs current]
  72. v1 [diff vs current]
  73. v1 [diff vs current]
  74. v1 [diff vs current]
  75. v1 [diff vs current]
  76. v1 [diff vs current]
  77. v1 [diff vs current]
  78. v1 [diff vs current]
  79. v1 [diff vs current]
  80. v1 [diff vs current]
  81. v1 [diff vs current]
  82. v1 [diff vs current]
  83. v1 [diff vs current]
  84. v1 [diff vs current]
  85. v1 [diff vs current]
  86. v1 [diff vs current]
  87. v1 [diff vs current]
  88. v1 [diff vs current]
  89. v1 [diff vs current]
  90. v1 [diff vs current]
  91. v1 [diff vs current]
  92. v2 [diff vs current]
  93. v1 [diff vs current]
  94. v1 [diff vs current]
  95. v1 [diff vs current]
  96. v1 [diff vs current]
  97. v1 [diff vs current]
  98. v1 [diff vs current]
  99. v1 [diff vs current]
  100. v1 [diff vs current]
  101. v1 [diff vs current]
  102. v1 [diff vs current]
  103. v2 [diff vs current]
  104. v1 [diff vs current]
  105. v1 [diff vs current]
  106. v1 [diff vs current]
  107. v1 [diff vs current]
  108. v1 [diff vs current]
  109. v1 [diff vs current]
  110. v1 [diff vs current]
  111. v1 [diff vs current]
  112. v1 [diff vs current]
  113. v1 [diff vs current]
  114. v1 [diff vs current]
  115. v1 [diff vs current]
  116. v1 [diff vs current]
  117. v1 [diff vs current]
  118. v1 [diff vs current]
  119. v1 [diff vs current]
  120. v1 [diff vs current]
  121. v1 [diff vs current]
  122. v1 [diff vs current]
  123. v1 [diff vs current]
  124. v1 [diff vs current]
  125. v1 [diff vs current]
  126. v2 [diff vs current]
  127. v1 [diff vs current]
  128. v1 [diff vs current]
  129. v1 [diff vs current]
  130. v2 [diff vs current]
  131. v1 [diff vs current]
  132. v1 [diff vs current]
  133. v1 [diff vs current]
  134. v1 [diff vs current]
  135. v1 [diff vs current]
  136. v1 [diff vs current]
  137. v2 [diff vs current]
  138. v3 [diff vs current]
  139. v1 [diff vs current]
  140. v1 [diff vs current]
  141. v1 [diff vs current]
  142. v2 [diff vs current]
  143. v1 [diff vs current]
  144. v1 [diff vs current]
  145. v1 [diff vs current]
  146. v2 [diff vs current]
  147. v1 [diff vs current]
  148. v1 [diff vs current]
  149. v1 [diff vs current]
  150. v1 [diff vs current]
  151. v2 [diff vs current]
  152. v1 [diff vs current]
  153. v2 [diff vs current]
  154. v1 [diff vs current]
  155. v1 [diff vs current]
  156. v1 [diff vs current]
  157. v2 [diff vs current]
  158. v1 [diff vs current]

[PATCH 4/9] netfilter: nf_conncount: split gc in two phases

From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2018-12-29 12:58:15
Also in: netfilter-devel
Subsystem: netfilter, networking [general], the rest · Maintainers: Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds 

From: Florian Westphal <fw@strlen.de>

The lockless workqueue garbage collector can race with packet path
garbage collector to delete list nodes, as it calls tree_nodes_free()
with the addresses of nodes that might have been free'd already from
another cpu.

To fix this, split gc into two phases.

One phase to perform gc on the connections: From a locking perspective,
this is the same as count_tree(): we hold rcu lock, but we do not
change the tree, we only change the nodes' contents.

The second phase acquires the tree lock and reaps empty nodes.
This avoids a race condition of the garbage collection vs.  packet path:
If a node has been free'd already, the second phase won't find it anymore.

This second phase is, from locking perspective, same as insert_tree().

The former only modifies nodes (list content, count), latter modifies
the tree itself (rb_erase or rb_insert).

Fixes: 5c789e131cbb9 ("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search")
Reviewed-by: Shawn Bohrer <redacted>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conncount.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index 8bb4ed85c262..753132e4afa8 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -500,16 +500,32 @@ static void tree_gc_worker(struct work_struct *work)
 	for (node = rb_first(root); node != NULL; node = rb_next(node)) {
 		rbconn = rb_entry(node, struct nf_conncount_rb, node);
 		if (nf_conncount_gc_list(data->net, &rbconn->list))
-			gc_nodes[gc_count++] = rbconn;
+			gc_count++;
 	}
 	rcu_read_unlock();
 
 	spin_lock_bh(&nf_conncount_locks[tree]);
+	if (gc_count < ARRAY_SIZE(gc_nodes))
+		goto next; /* do not bother */
 
-	if (gc_count) {
-		tree_nodes_free(root, gc_nodes, gc_count);
+	gc_count = 0;
+	node = rb_first(root);
+	while (node != NULL) {
+		rbconn = rb_entry(node, struct nf_conncount_rb, node);
+		node = rb_next(node);
+
+		if (rbconn->list.count > 0)
+			continue;
+
+		gc_nodes[gc_count++] = rbconn;
+		if (gc_count >= ARRAY_SIZE(gc_nodes)) {
+			tree_nodes_free(root, gc_nodes, gc_count);
+			gc_count = 0;
+		}
 	}
 
+	tree_nodes_free(root, gc_nodes, gc_count);
+next:
 	clear_bit(tree, data->pending_trees);
 
 	next_tree = (tree + 1) % CONNCOUNT_SLOTS;
-- 
2.11.0
Other recent patches touching these files
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help