target/linux/generic/patches-3.18/080-11-fib_trie-Push-rcu_read_lock-unlock-to-callers.patch

   1 From: Alexander Duyck <alexander.h.duyck@redhat.com>
   2 Date: Wed, 31 Dec 2014 10:56:24 -0800
   3 Subject: [PATCH] fib_trie: Push rcu_read_lock/unlock to callers
   4
   5 This change is to start cleaning up some of the rcu_read_lock/unlock
   6 handling.  I realized while reviewing the code there are several spots that
   7 I don't believe are being handled correctly or are masking warnings by
   8 locally calling rcu_read_lock/unlock instead of calling them at the correct
   9 level.
  10
  11 A common example is a call to fib_get_table followed by fib_table_lookup.
  12 The rcu_read_lock/unlock ought to wrap both but there are several spots where
  13 they were not wrapped.
  14
  15 Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
  16 Signed-off-by: David S. Miller <davem@davemloft.net>
  17 ---
  18
  19 --- a/include/net/ip_fib.h
  20 +++ b/include/net/ip_fib.h
  21 @@ -222,16 +222,19 @@ static inline struct fib_table *fib_new_
  22  static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
  23                              struct fib_result *res)
  24  {
  25 -       struct fib_table *table;
  26 +       int err = -ENETUNREACH;
  27
  28 -       table = fib_get_table(net, RT_TABLE_LOCAL);
  29 -       if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))
  30 -               return 0;
  31 -
  32 -       table = fib_get_table(net, RT_TABLE_MAIN);
  33 -       if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))
  34 -               return 0;
  35 -       return -ENETUNREACH;
  36 +       rcu_read_lock();
  37 +
  38 +       if (!fib_table_lookup(fib_get_table(net, RT_TABLE_LOCAL), flp, res,
  39 +                             FIB_LOOKUP_NOREF) ||
  40 +           !fib_table_lookup(fib_get_table(net, RT_TABLE_MAIN), flp, res,
  41 +                             FIB_LOOKUP_NOREF))
  42 +               err = 0;
  43 +
  44 +       rcu_read_unlock();
  45 +
  46 +       return err;
  47  }
  48
  49  #else /* CONFIG_IP_MULTIPLE_TABLES */
  50 @@ -247,20 +250,25 @@ static inline int fib_lookup(struct net
  51                              struct fib_result *res)
  52  {
  53         if (!net->ipv4.fib_has_custom_rules) {
  54 +               int err = -ENETUNREACH;
  55 +
  56 +               rcu_read_lock();
  57 +
  58                 res->tclassid = 0;
  59 -               if (net->ipv4.fib_local &&
  60 -                   !fib_table_lookup(net->ipv4.fib_local, flp, res,
  61 -                                     FIB_LOOKUP_NOREF))
  62 -                       return 0;
  63 -               if (net->ipv4.fib_main &&
  64 -                   !fib_table_lookup(net->ipv4.fib_main, flp, res,
  65 -                                     FIB_LOOKUP_NOREF))
  66 -                       return 0;
  67 -               if (net->ipv4.fib_default &&
  68 -                   !fib_table_lookup(net->ipv4.fib_default, flp, res,
  69 -                                     FIB_LOOKUP_NOREF))
  70 -                       return 0;
  71 -               return -ENETUNREACH;
  72 +               if ((net->ipv4.fib_local &&
  73 +                    !fib_table_lookup(net->ipv4.fib_local, flp, res,
  74 +                                      FIB_LOOKUP_NOREF)) ||
  75 +                   (net->ipv4.fib_main &&
  76 +                    !fib_table_lookup(net->ipv4.fib_main, flp, res,
  77 +                                      FIB_LOOKUP_NOREF)) ||
  78 +                   (net->ipv4.fib_default &&
  79 +                    !fib_table_lookup(net->ipv4.fib_default, flp, res,
  80 +                                      FIB_LOOKUP_NOREF)))
  81 +                       err = 0;
  82 +
  83 +               rcu_read_unlock();
  84 +
  85 +               return err;
  86         }
  87         return __fib_lookup(net, flp, res);
  88  }
  89 --- a/net/ipv4/fib_frontend.c
  90 +++ b/net/ipv4/fib_frontend.c
  91 @@ -109,6 +109,7 @@ struct fib_table *fib_new_table(struct n
  92         return tb;
  93  }
  94
  95 +/* caller must hold either rtnl or rcu read lock */
  96  struct fib_table *fib_get_table(struct net *net, u32 id)
  97  {
  98         struct fib_table *tb;
  99 @@ -119,15 +120,11 @@ struct fib_table *fib_get_table(struct n
 100                 id = RT_TABLE_MAIN;
 101         h = id & (FIB_TABLE_HASHSZ - 1);
 102
 103 -       rcu_read_lock();
 104         head = &net->ipv4.fib_table_hash[h];
 105         hlist_for_each_entry_rcu(tb, head, tb_hlist) {
 106 -               if (tb->tb_id == id) {
 107 -                       rcu_read_unlock();
 108 +               if (tb->tb_id == id)
 109                         return tb;
 110 -               }
 111         }
 112 -       rcu_read_unlock();
 113         return NULL;
 114  }
 115  #endif /* CONFIG_IP_MULTIPLE_TABLES */
 116 @@ -167,16 +164,18 @@ static inline unsigned int __inet_dev_ad
 117         if (ipv4_is_multicast(addr))
 118                 return RTN_MULTICAST;
 119
 120 +       rcu_read_lock();
 121 +
 122         local_table = fib_get_table(net, RT_TABLE_LOCAL);
 123         if (local_table) {
 124                 ret = RTN_UNICAST;
 125 -               rcu_read_lock();
 126                 if (!fib_table_lookup(local_table, &fl4, &res, FIB_LOOKUP_NOREF)) {
 127                         if (!dev || dev == res.fi->fib_dev)
 128                                 ret = res.type;
 129                 }
 130 -               rcu_read_unlock();
 131         }
 132 +
 133 +       rcu_read_unlock();
 134         return ret;
 135  }
 136
 137 @@ -923,7 +922,7 @@ no_promotions:
 138  #undef BRD1_OK
 139  }
 140
 141 -static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb)
 142 +static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
 143  {
 144
 145         struct fib_result       res;
 146 @@ -933,6 +932,11 @@ static void nl_fib_lookup(struct fib_res
 147                 .flowi4_tos = frn->fl_tos,
 148                 .flowi4_scope = frn->fl_scope,
 149         };
 150 +       struct fib_table *tb;
 151 +
 152 +       rcu_read_lock();
 153 +
 154 +       tb = fib_get_table(net, frn->tb_id_in);
 155
 156         frn->err = -ENOENT;
 157         if (tb) {
 158 @@ -949,6 +953,8 @@ static void nl_fib_lookup(struct fib_res
 159                 }
 160                 local_bh_enable();
 161         }
 162 +
 163 +       rcu_read_unlock();
 164  }
 165
 166  static void nl_fib_input(struct sk_buff *skb)
 167 @@ -956,7 +962,6 @@ static void nl_fib_input(struct sk_buff
 168         struct net *net;
 169         struct fib_result_nl *frn;
 170         struct nlmsghdr *nlh;
 171 -       struct fib_table *tb;
 172         u32 portid;
 173
 174         net = sock_net(skb->sk);
 175 @@ -972,9 +977,7 @@ static void nl_fib_input(struct sk_buff
 176         nlh = nlmsg_hdr(skb);
 177
 178         frn = (struct fib_result_nl *) nlmsg_data(nlh);
 179 -       tb = fib_get_table(net, frn->tb_id_in);
 180 -
 181 -       nl_fib_lookup(frn, tb);
 182 +       nl_fib_lookup(net, frn);
 183
 184         portid = NETLINK_CB(skb).portid;      /* netlink portid */
 185         NETLINK_CB(skb).portid = 0;        /* from kernel */
 186 --- a/net/ipv4/fib_rules.c
 187 +++ b/net/ipv4/fib_rules.c
 188 @@ -81,27 +81,25 @@ static int fib4_rule_action(struct fib_r
 189                 break;
 190
 191         case FR_ACT_UNREACHABLE:
 192 -               err = -ENETUNREACH;
 193 -               goto errout;
 194 +               return -ENETUNREACH;
 195
 196         case FR_ACT_PROHIBIT:
 197 -               err = -EACCES;
 198 -               goto errout;
 199 +               return -EACCES;
 200
 201         case FR_ACT_BLACKHOLE:
 202         default:
 203 -               err = -EINVAL;
 204 -               goto errout;
 205 +               return -EINVAL;
 206         }
 207
 208 +       rcu_read_lock();
 209 +
 210         tbl = fib_get_table(rule->fr_net, rule->table);
 211 -       if (!tbl)
 212 -               goto errout;
 213 +       if (tbl)
 214 +               err = fib_table_lookup(tbl, &flp->u.ip4,
 215 +                                      (struct fib_result *)arg->result,
 216 +                                      arg->flags);
 217
 218 -       err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
 219 -       if (err > 0)
 220 -               err = -EAGAIN;
 221 -errout:
 222 +       rcu_read_unlock();
 223         return err;
 224  }
 225
 226 --- a/net/ipv4/fib_trie.c
 227 +++ b/net/ipv4/fib_trie.c
 228 @@ -1181,72 +1181,6 @@ err:
 229         return err;
 230  }
 231
 232 -/* should be called with rcu_read_lock */
 233 -static int check_leaf(struct fib_table *tb, struct trie *t, struct tnode *l,
 234 -                     t_key key,  const struct flowi4 *flp,
 235 -                     struct fib_result *res, int fib_flags)
 236 -{
 237 -       struct leaf_info *li;
 238 -       struct hlist_head *hhead = &l->list;
 239 -
 240 -       hlist_for_each_entry_rcu(li, hhead, hlist) {
 241 -               struct fib_alias *fa;
 242 -
 243 -               if (l->key != (key & li->mask_plen))
 244 -                       continue;
 245 -
 246 -               list_for_each_entry_rcu(fa, &li->falh, fa_list) {
 247 -                       struct fib_info *fi = fa->fa_info;
 248 -                       int nhsel, err;
 249 -
 250 -                       if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
 251 -                               continue;
 252 -                       if (fi->fib_dead)
 253 -                               continue;
 254 -                       if (fa->fa_info->fib_scope < flp->flowi4_scope)
 255 -                               continue;
 256 -                       fib_alias_accessed(fa);
 257 -                       err = fib_props[fa->fa_type].error;
 258 -                       if (unlikely(err < 0)) {
 259 -#ifdef CONFIG_IP_FIB_TRIE_STATS
 260 -                               this_cpu_inc(t->stats->semantic_match_passed);
 261 -#endif
 262 -                               return err;
 263 -                       }
 264 -                       if (fi->fib_flags & RTNH_F_DEAD)
 265 -                               continue;
 266 -                       for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
 267 -                               const struct fib_nh *nh = &fi->fib_nh[nhsel];
 268 -
 269 -                               if (nh->nh_flags & RTNH_F_DEAD)
 270 -                                       continue;
 271 -                               if (flp->flowi4_oif && flp->flowi4_oif != nh->nh_oif)
 272 -                                       continue;
 273 -
 274 -#ifdef CONFIG_IP_FIB_TRIE_STATS
 275 -                               this_cpu_inc(t->stats->semantic_match_passed);
 276 -#endif
 277 -                               res->prefixlen = li->plen;
 278 -                               res->nh_sel = nhsel;
 279 -                               res->type = fa->fa_type;
 280 -                               res->scope = fi->fib_scope;
 281 -                               res->fi = fi;
 282 -                               res->table = tb;
 283 -                               res->fa_head = &li->falh;
 284 -                               if (!(fib_flags & FIB_LOOKUP_NOREF))
 285 -                                       atomic_inc(&fi->fib_clntref);
 286 -                               return 0;
 287 -                       }
 288 -               }
 289 -
 290 -#ifdef CONFIG_IP_FIB_TRIE_STATS
 291 -               this_cpu_inc(t->stats->semantic_match_miss);
 292 -#endif
 293 -       }
 294 -
 295 -       return 1;
 296 -}
 297 -
 298  static inline t_key prefix_mismatch(t_key key, struct tnode *n)
 299  {
 300         t_key prefix = n->key;
 301 @@ -1254,6 +1188,7 @@ static inline t_key prefix_mismatch(t_ke
 302         return (key ^ prefix) & (prefix | -prefix);
 303  }
 304
 305 +/* should be called with rcu_read_lock */
 306  int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 307                      struct fib_result *res, int fib_flags)
 308  {
 309 @@ -1263,14 +1198,12 @@ int fib_table_lookup(struct fib_table *t
 310  #endif
 311         const t_key key = ntohl(flp->daddr);
 312         struct tnode *n, *pn;
 313 +       struct leaf_info *li;
 314         t_key cindex;
 315 -       int ret = 1;
 316 -
 317 -       rcu_read_lock();
 318
 319         n = rcu_dereference(t->trie);
 320         if (!n)
 321 -               goto failed;
 322 +               return -EAGAIN;
 323
 324  #ifdef CONFIG_IP_FIB_TRIE_STATS
 325         this_cpu_inc(stats->gets);
 326 @@ -1350,7 +1283,7 @@ backtrace:
 327
 328                                 pn = node_parent_rcu(pn);
 329                                 if (unlikely(!pn))
 330 -                                       goto failed;
 331 +                                       return -EAGAIN;
 332  #ifdef CONFIG_IP_FIB_TRIE_STATS
 333                                 this_cpu_inc(stats->backtrack);
 334  #endif
 335 @@ -1368,12 +1301,62 @@ backtrace:
 336
 337  found:
 338         /* Step 3: Process the leaf, if that fails fall back to backtracing */
 339 -       ret = check_leaf(tb, t, n, key, flp, res, fib_flags);
 340 -       if (unlikely(ret > 0))
 341 -               goto backtrace;
 342 -failed:
 343 -       rcu_read_unlock();
 344 -       return ret;
 345 +       hlist_for_each_entry_rcu(li, &n->list, hlist) {
 346 +               struct fib_alias *fa;
 347 +
 348 +               if ((key ^ n->key) & li->mask_plen)
 349 +                       continue;
 350 +
 351 +               list_for_each_entry_rcu(fa, &li->falh, fa_list) {
 352 +                       struct fib_info *fi = fa->fa_info;
 353 +                       int nhsel, err;
 354 +
 355 +                       if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
 356 +                               continue;
 357 +                       if (fi->fib_dead)
 358 +                               continue;
 359 +                       if (fa->fa_info->fib_scope < flp->flowi4_scope)
 360 +                               continue;
 361 +                       fib_alias_accessed(fa);
 362 +                       err = fib_props[fa->fa_type].error;
 363 +                       if (unlikely(err < 0)) {
 364 +#ifdef CONFIG_IP_FIB_TRIE_STATS
 365 +                               this_cpu_inc(stats->semantic_match_passed);
 366 +#endif
 367 +                               return err;
 368 +                       }
 369 +                       if (fi->fib_flags & RTNH_F_DEAD)
 370 +                               continue;
 371 +                       for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
 372 +                               const struct fib_nh *nh = &fi->fib_nh[nhsel];
 373 +
 374 +                               if (nh->nh_flags & RTNH_F_DEAD)
 375 +                                       continue;
 376 +                               if (flp->flowi4_oif && flp->flowi4_oif != nh->nh_oif)
 377 +                                       continue;
 378 +
 379 +                               if (!(fib_flags & FIB_LOOKUP_NOREF))
 380 +                                       atomic_inc(&fi->fib_clntref);
 381 +
 382 +                               res->prefixlen = li->plen;
 383 +                               res->nh_sel = nhsel;
 384 +                               res->type = fa->fa_type;
 385 +                               res->scope = fi->fib_scope;
 386 +                               res->fi = fi;
 387 +                               res->table = tb;
 388 +                               res->fa_head = &li->falh;
 389 +#ifdef CONFIG_IP_FIB_TRIE_STATS
 390 +                               this_cpu_inc(stats->semantic_match_passed);
 391 +#endif
 392 +                               return err;
 393 +                       }
 394 +               }
 395 +
 396 +#ifdef CONFIG_IP_FIB_TRIE_STATS
 397 +               this_cpu_inc(stats->semantic_match_miss);
 398 +#endif
 399 +       }
 400 +       goto backtrace;
 401  }
 402  EXPORT_SYMBOL_GPL(fib_table_lookup);
 403