Thomas Gleixner | a85036f | 2019-05-20 09:19:03 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * NET3: Garbage Collector For AF_UNIX sockets |
| 4 | * |
| 5 | * Garbage Collector: |
| 6 | * Copyright (C) Barak A. Pearlmutter. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | * |
| 8 | * Chopped about by Alan Cox 22/3/96 to make it fit the AF_UNIX socket problem. |
| 9 | * If it doesn't work blame me, it worked when Barak sent it. |
| 10 | * |
| 11 | * Assumptions: |
| 12 | * |
| 13 | * - object w/ a bit |
| 14 | * - free list |
| 15 | * |
| 16 | * Current optimizations: |
| 17 | * |
| 18 | * - explicit stack instead of recursion |
| 19 | * - tail recurse on first born instead of immediate push/pop |
| 20 | * - we gather the stuff that should not be killed into tree |
| 21 | * and stack is just a path from root to the current pointer. |
| 22 | * |
| 23 | * Future optimizations: |
| 24 | * |
| 25 | * - don't just push entire root set; process in place |
| 26 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | * Fixes: |
| 28 | * Alan Cox 07 Sept 1997 Vmalloc internal stack as needed. |
| 29 | * Cope with changing max_files. |
| 30 | * Al Viro 11 Oct 1998 |
| 31 | * Graph may have cycles. That is, we can send the descriptor |
| 32 | * of foo to bar and vice versa. Current code chokes on that. |
| 33 | * Fix: move SCM_RIGHTS ones into the separate list and then |
| 34 | * skb_free() them all instead of doing explicit fput's. |
| 35 | * Another problem: since fput() may block somebody may |
| 36 | * create a new unix_socket when we are in the middle of sweep |
| 37 | * phase. Fix: revert the logic wrt MARKED. Mark everything |
| 38 | * upon the beginning and unmark non-junk ones. |
| 39 | * |
| 40 | * [12 Oct 1998] AAARGH! New code purges all SCM_RIGHTS |
| 41 | * sent to connect()'ed but still not accept()'ed sockets. |
| 42 | * Fixed. Old code had slightly different problem here: |
| 43 | * extra fput() in situation when we passed the descriptor via |
| 44 | * such socket and closed it (descriptor). That would happen on |
| 45 | * each unix_gc() until the accept(). Since the struct file in |
| 46 | * question would go to the free list and might be reused... |
| 47 | * That might be the reason of random oopses on filp_close() |
| 48 | * in unrelated processes. |
| 49 | * |
| 50 | * AV 28 Feb 1999 |
| 51 | * Kill the explicit allocation of stack. Now we keep the tree |
| 52 | * with root in dummy + pointer (gc_current) to one of the nodes. |
| 53 | * Stack is represented as path from gc_current to dummy. Unmark |
| 54 | * now means "add to tree". Push == "make it a son of gc_current". |
| 55 | * Pop == "move gc_current to parent". We keep only pointers to |
| 56 | * parents (->gc_tree). |
| 57 | * AV 1 Mar 1999 |
| 58 | * Damn. Added missing check for ->dead in listen queues scanning. |
| 59 | * |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 60 | * Miklos Szeredi 25 Jun 2007 |
| 61 | * Reimplement with a cycle collecting algorithm. This should |
| 62 | * solve several problems with the previous code, like being racy |
| 63 | * wrt receive and holding up unrelated socket operations. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | */ |
YOSHIFUJI Hideaki | ac7bfa6 | 2007-02-09 23:25:23 +0900 | [diff] [blame] | 65 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | #include <linux/string.h> |
| 68 | #include <linux/socket.h> |
| 69 | #include <linux/un.h> |
| 70 | #include <linux/net.h> |
| 71 | #include <linux/fs.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | #include <linux/skbuff.h> |
| 73 | #include <linux/netdevice.h> |
| 74 | #include <linux/file.h> |
| 75 | #include <linux/proc_fs.h> |
Arjan van de Ven | 4a3e2f7 | 2006-03-20 22:33:17 -0800 | [diff] [blame] | 76 | #include <linux/mutex.h> |
dann frazier | 5f23b73 | 2008-11-26 15:32:27 -0800 | [diff] [blame] | 77 | #include <linux/wait.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | |
| 79 | #include <net/sock.h> |
| 80 | #include <net/af_unix.h> |
| 81 | #include <net/scm.h> |
Arnaldo Carvalho de Melo | c752f07 | 2005-08-09 20:08:28 -0700 | [diff] [blame] | 82 | #include <net/tcp_states.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | |
Jens Axboe | f4e6587 | 2019-02-08 09:01:44 -0700 | [diff] [blame] | 84 | #include "scm.h" |
| 85 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | /* Internal data structures and random procedures: */ |
| 87 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 88 | static LIST_HEAD(gc_candidates); |
dann frazier | 5f23b73 | 2008-11-26 15:32:27 -0800 | [diff] [blame] | 89 | static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 91 | static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *), |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 92 | struct sk_buff_head *hitlist) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | { |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 94 | struct sk_buff *skb; |
| 95 | struct sk_buff *next; |
| 96 | |
| 97 | spin_lock(&x->sk_receive_queue.lock); |
Ilpo Järvinen | a2f3be1 | 2010-05-03 03:22:18 +0000 | [diff] [blame] | 98 | skb_queue_walk_safe(&x->sk_receive_queue, skb, next) { |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 99 | /* Do we have file descriptors ? */ |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 100 | if (UNIXCB(skb).fp) { |
| 101 | bool hit = false; |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 102 | /* Process the descriptors of this socket */ |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 103 | int nfd = UNIXCB(skb).fp->count; |
| 104 | struct file **fp = UNIXCB(skb).fp->fp; |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 105 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 106 | while (nfd--) { |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 107 | /* Get the socket the fd matches if it indeed does so */ |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 108 | struct sock *sk = unix_get_socket(*fp++); |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 109 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 110 | if (sk) { |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 111 | struct unix_sock *u = unix_sk(sk); |
| 112 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 113 | /* Ignore non-candidates, they could |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 114 | * have been added to the queues after |
| 115 | * starting the garbage collection |
| 116 | */ |
Eric Dumazet | 60bc851 | 2013-05-01 05:24:03 +0000 | [diff] [blame] | 117 | if (test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) { |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 118 | hit = true; |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 119 | |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 120 | func(u); |
| 121 | } |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 122 | } |
| 123 | } |
| 124 | if (hit && hitlist != NULL) { |
| 125 | __skb_unlink(skb, &x->sk_receive_queue); |
| 126 | __skb_queue_tail(hitlist, skb); |
| 127 | } |
| 128 | } |
| 129 | } |
| 130 | spin_unlock(&x->sk_receive_queue.lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | } |
| 132 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 133 | static void scan_children(struct sock *x, void (*func)(struct unix_sock *), |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 134 | struct sk_buff_head *hitlist) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | { |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 136 | if (x->sk_state != TCP_LISTEN) { |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 137 | scan_inflight(x, func, hitlist); |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 138 | } else { |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 139 | struct sk_buff *skb; |
| 140 | struct sk_buff *next; |
| 141 | struct unix_sock *u; |
| 142 | LIST_HEAD(embryos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 144 | /* For a listening socket collect the queued embryos |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 145 | * and perform a scan on them as well. |
| 146 | */ |
| 147 | spin_lock(&x->sk_receive_queue.lock); |
Ilpo Järvinen | a2f3be1 | 2010-05-03 03:22:18 +0000 | [diff] [blame] | 148 | skb_queue_walk_safe(&x->sk_receive_queue, skb, next) { |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 149 | u = unix_sk(skb->sk); |
| 150 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 151 | /* An embryo cannot be in-flight, so it's safe |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 152 | * to use the list link. |
| 153 | */ |
| 154 | BUG_ON(!list_empty(&u->link)); |
| 155 | list_add_tail(&u->link, &embryos); |
| 156 | } |
| 157 | spin_unlock(&x->sk_receive_queue.lock); |
| 158 | |
| 159 | while (!list_empty(&embryos)) { |
| 160 | u = list_entry(embryos.next, struct unix_sock, link); |
| 161 | scan_inflight(&u->sk, func, hitlist); |
| 162 | list_del_init(&u->link); |
| 163 | } |
| 164 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | } |
| 166 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 167 | static void dec_inflight(struct unix_sock *usk) |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 168 | { |
Kuniyuki Iwashima | 65e0a92 | 2024-01-23 09:08:53 -0800 | [diff] [blame] | 169 | usk->inflight--; |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 170 | } |
| 171 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 172 | static void inc_inflight(struct unix_sock *usk) |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 173 | { |
Kuniyuki Iwashima | 65e0a92 | 2024-01-23 09:08:53 -0800 | [diff] [blame] | 174 | usk->inflight++; |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 175 | } |
| 176 | |
Pavel Emelyanov | 5c80f1a | 2007-11-10 22:07:13 -0800 | [diff] [blame] | 177 | static void inc_inflight_move_tail(struct unix_sock *u) |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 178 | { |
Kuniyuki Iwashima | 65e0a92 | 2024-01-23 09:08:53 -0800 | [diff] [blame] | 179 | u->inflight++; |
| 180 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 181 | /* If this still might be part of a cycle, move it to the end |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 182 | * of the list, so that it's checked even if it was already |
| 183 | * passed over |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 184 | */ |
Eric Dumazet | 60bc851 | 2013-05-01 05:24:03 +0000 | [diff] [blame] | 185 | if (test_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags)) |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 186 | list_move_tail(&u->link, &gc_candidates); |
| 187 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | |
Fabian Frederick | 505e907 | 2014-10-07 23:02:15 +0200 | [diff] [blame] | 189 | static bool gc_in_progress; |
Eric Dumazet | 9915672 | 2010-11-24 09:15:27 -0800 | [diff] [blame] | 190 | #define UNIX_INFLIGHT_TRIGGER_GC 16000 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | |
dann frazier | 5f23b73 | 2008-11-26 15:32:27 -0800 | [diff] [blame] | 192 | void wait_for_unix_gc(void) |
| 193 | { |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 194 | /* If number of inflight sockets is insane, |
Eric Dumazet | 9915672 | 2010-11-24 09:15:27 -0800 | [diff] [blame] | 195 | * force a garbage collect right now. |
Eric Dumazet | 3872d146 | 2022-01-14 08:43:28 -0800 | [diff] [blame] | 196 | * Paired with the WRITE_ONCE() in unix_inflight(), |
| 197 | * unix_notinflight() and gc_in_progress(). |
Eric Dumazet | 9915672 | 2010-11-24 09:15:27 -0800 | [diff] [blame] | 198 | */ |
Eric Dumazet | 3872d146 | 2022-01-14 08:43:28 -0800 | [diff] [blame] | 199 | if (READ_ONCE(unix_tot_inflight) > UNIX_INFLIGHT_TRIGGER_GC && |
| 200 | !READ_ONCE(gc_in_progress)) |
Eric Dumazet | 9915672 | 2010-11-24 09:15:27 -0800 | [diff] [blame] | 201 | unix_gc(); |
dann frazier | 5f23b73 | 2008-11-26 15:32:27 -0800 | [diff] [blame] | 202 | wait_event(unix_gc_wait, gc_in_progress == false); |
| 203 | } |
| 204 | |
| 205 | /* The external entry point: unix_gc() */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 206 | void unix_gc(void) |
| 207 | { |
Pavel Begunkov | 813d8fe | 2022-10-16 22:42:54 +0100 | [diff] [blame] | 208 | struct sk_buff *next_skb, *skb; |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 209 | struct unix_sock *u; |
| 210 | struct unix_sock *next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | struct sk_buff_head hitlist; |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 212 | struct list_head cursor; |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 213 | LIST_HEAD(not_cycle_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 215 | spin_lock(&unix_gc_lock); |
| 216 | |
| 217 | /* Avoid a recursive GC. */ |
| 218 | if (gc_in_progress) |
| 219 | goto out; |
| 220 | |
Eric Dumazet | 3872d146 | 2022-01-14 08:43:28 -0800 | [diff] [blame] | 221 | /* Paired with READ_ONCE() in wait_for_unix_gc(). */ |
| 222 | WRITE_ONCE(gc_in_progress, true); |
| 223 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 224 | /* First, select candidates for garbage collection. Only |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 225 | * in-flight sockets are considered, and from those only ones |
| 226 | * which don't have any external reference. |
| 227 | * |
| 228 | * Holding unix_gc_lock will protect these candidates from |
| 229 | * being detached, and hence from gaining an external |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 230 | * reference. Since there are no possible receivers, all |
| 231 | * buffers currently on the candidates' queues stay there |
| 232 | * during the garbage collection. |
| 233 | * |
| 234 | * We also know that no new candidate can be added onto the |
| 235 | * receive queues. Other, non candidate sockets _can_ be |
| 236 | * added to queue, so we must make sure only to touch |
| 237 | * candidates. |
Michal Luczaj | e8e652b | 2024-04-09 22:09:39 +0200 | [diff] [blame^] | 238 | * |
| 239 | * Embryos, though never candidates themselves, affect which |
| 240 | * candidates are reachable by the garbage collector. Before |
| 241 | * being added to a listener's queue, an embryo may already |
| 242 | * receive data carrying SCM_RIGHTS, potentially making the |
| 243 | * passed socket a candidate that is not yet reachable by the |
| 244 | * collector. It becomes reachable once the embryo is |
| 245 | * enqueued. Therefore, we must ensure that no SCM-laden |
| 246 | * embryo appears in a (candidate) listener's queue between |
| 247 | * consecutive scan_children() calls. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 248 | */ |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 249 | list_for_each_entry_safe(u, next, &gc_inflight_list, link) { |
Michal Luczaj | e8e652b | 2024-04-09 22:09:39 +0200 | [diff] [blame^] | 250 | struct sock *sk = &u->sk; |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 251 | long total_refs; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | |
Michal Luczaj | e8e652b | 2024-04-09 22:09:39 +0200 | [diff] [blame^] | 253 | total_refs = file_count(sk->sk_socket->file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 254 | |
Kuniyuki Iwashima | 65e0a92 | 2024-01-23 09:08:53 -0800 | [diff] [blame] | 255 | BUG_ON(!u->inflight); |
| 256 | BUG_ON(total_refs < u->inflight); |
| 257 | if (total_refs == u->inflight) { |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 258 | list_move_tail(&u->link, &gc_candidates); |
Eric Dumazet | 60bc851 | 2013-05-01 05:24:03 +0000 | [diff] [blame] | 259 | __set_bit(UNIX_GC_CANDIDATE, &u->gc_flags); |
| 260 | __set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags); |
Michal Luczaj | e8e652b | 2024-04-09 22:09:39 +0200 | [diff] [blame^] | 261 | |
| 262 | if (sk->sk_state == TCP_LISTEN) { |
| 263 | unix_state_lock(sk); |
| 264 | unix_state_unlock(sk); |
| 265 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 266 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | } |
| 268 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 269 | /* Now remove all internal in-flight reference to children of |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 270 | * the candidates. |
| 271 | */ |
| 272 | list_for_each_entry(u, &gc_candidates, link) |
| 273 | scan_children(&u->sk, dec_inflight, NULL); |
| 274 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 275 | /* Restore the references for children of all candidates, |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 276 | * which have remaining references. Do this recursively, so |
| 277 | * only those remain, which form cyclic references. |
| 278 | * |
| 279 | * Use a "cursor" link, to make the list traversal safe, even |
| 280 | * though elements might be moved about. |
| 281 | */ |
| 282 | list_add(&cursor, &gc_candidates); |
| 283 | while (cursor.next != &gc_candidates) { |
| 284 | u = list_entry(cursor.next, struct unix_sock, link); |
| 285 | |
| 286 | /* Move cursor to after the current position. */ |
| 287 | list_move(&cursor, &u->link); |
| 288 | |
Kuniyuki Iwashima | 65e0a92 | 2024-01-23 09:08:53 -0800 | [diff] [blame] | 289 | if (u->inflight) { |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 290 | list_move_tail(&u->link, ¬_cycle_list); |
Eric Dumazet | 60bc851 | 2013-05-01 05:24:03 +0000 | [diff] [blame] | 291 | __clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags); |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 292 | scan_children(&u->sk, inc_inflight_move_tail, NULL); |
| 293 | } |
| 294 | } |
| 295 | list_del(&cursor); |
| 296 | |
Andrey Ulanov | 7df9c24 | 2017-03-14 20:16:42 -0700 | [diff] [blame] | 297 | /* Now gc_candidates contains only garbage. Restore original |
| 298 | * inflight counters for these as well, and remove the skbuffs |
| 299 | * which are creating the cycle(s). |
| 300 | */ |
| 301 | skb_queue_head_init(&hitlist); |
| 302 | list_for_each_entry(u, &gc_candidates, link) |
| 303 | scan_children(&u->sk, inc_inflight, &hitlist); |
| 304 | |
Jason Eastman | d1ab39f | 2015-04-22 00:56:42 -0600 | [diff] [blame] | 305 | /* not_cycle_list contains those sockets which do not make up a |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 306 | * cycle. Restore these to the inflight list. |
| 307 | */ |
| 308 | while (!list_empty(¬_cycle_list)) { |
| 309 | u = list_entry(not_cycle_list.next, struct unix_sock, link); |
Eric Dumazet | 60bc851 | 2013-05-01 05:24:03 +0000 | [diff] [blame] | 310 | __clear_bit(UNIX_GC_CANDIDATE, &u->gc_flags); |
Miklos Szeredi | 6209344 | 2008-11-09 15:23:57 +0100 | [diff] [blame] | 311 | list_move_tail(&u->link, &gc_inflight_list); |
| 312 | } |
| 313 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 314 | spin_unlock(&unix_gc_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 315 | |
Pavel Begunkov | 813d8fe | 2022-10-16 22:42:54 +0100 | [diff] [blame] | 316 | /* We need io_uring to clean its registered files, ignore all io_uring |
| 317 | * originated skbs. It's fine as io_uring doesn't keep references to |
| 318 | * other io_uring instances and so killing all other files in the cycle |
| 319 | * will put all io_uring references forcing it to go through normal |
| 320 | * release.path eventually putting registered files. |
| 321 | */ |
| 322 | skb_queue_walk_safe(&hitlist, skb, next_skb) { |
| 323 | if (skb->scm_io_uring) { |
| 324 | __skb_unlink(skb, &hitlist); |
| 325 | skb_queue_tail(&skb->sk->sk_receive_queue, skb); |
| 326 | } |
| 327 | } |
| 328 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 329 | /* Here we are. Hitlist is filled. Die. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 330 | __skb_queue_purge(&hitlist); |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 331 | |
| 332 | spin_lock(&unix_gc_lock); |
| 333 | |
Pavel Begunkov | 813d8fe | 2022-10-16 22:42:54 +0100 | [diff] [blame] | 334 | /* There could be io_uring registered files, just push them back to |
| 335 | * the inflight list |
| 336 | */ |
| 337 | list_for_each_entry_safe(u, next, &gc_candidates, link) |
| 338 | list_move_tail(&u->link, &gc_inflight_list); |
| 339 | |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 340 | /* All candidates should have been detached by now. */ |
| 341 | BUG_ON(!list_empty(&gc_candidates)); |
Eric Dumazet | 3872d146 | 2022-01-14 08:43:28 -0800 | [diff] [blame] | 342 | |
| 343 | /* Paired with READ_ONCE() in wait_for_unix_gc(). */ |
| 344 | WRITE_ONCE(gc_in_progress, false); |
| 345 | |
dann frazier | 5f23b73 | 2008-11-26 15:32:27 -0800 | [diff] [blame] | 346 | wake_up(&unix_gc_wait); |
Miklos Szeredi | 1fd05ba | 2007-07-11 14:22:39 -0700 | [diff] [blame] | 347 | |
| 348 | out: |
| 349 | spin_unlock(&unix_gc_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 350 | } |