rhashtable: accept GFP flags in rhashtable_walk_init

In certain cases, the 802.11 mesh pathtable code wants to
iterate over all of the entries in the forwarding table from
the receive path, which is inside an RCU read-side critical
section.  Enable walks inside atomic sections by allowing
GFP_ATOMIC allocations for the walker state.

Change all existing callsites to pass in GFP_KERNEL.

Acked-by: Thomas Graf <[email protected]>
Signed-off-by: Bob Copeland <[email protected]>
[also adjust gfs2/glock.c and rhashtable tests]
Signed-off-by: Johannes Berg <[email protected]>

Author: bcopeland

fs/gfs2/glock.c

@@ -1913,7 +1913,7 @@ static int gfs2_glocks_open(struct inode *inode, struct file *file)
 		if (seq->buf)
 			seq->size = GFS2_SEQ_GOODSIZE;
 		gi->gl = NULL;
-		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);
+		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti, GFP_KERNEL);
 	}
 	return ret;
 }
@@ -1941,7 +1941,7 @@ static int gfs2_glstats_open(struct inode *inode, struct file *file)
 		if (seq->buf)
 			seq->size = GFS2_SEQ_GOODSIZE;
 		gi->gl = NULL;
-		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);
+		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti, GFP_KERNEL);
 	}
 	return ret;
 }

include/linux/rhashtable.h

@@ -346,7 +346,8 @@ struct bucket_table *rhashtable_insert_slow(struct rhashtable *ht,
 					    struct bucket_table *old_tbl);
 int rhashtable_insert_rehash(struct rhashtable *ht, struct bucket_table *tbl);
 
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter);
+int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
+			 gfp_t gfp);
 void rhashtable_walk_exit(struct rhashtable_iter *iter);
 int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU);
 void *rhashtable_walk_next(struct rhashtable_iter *iter);

lib/rhashtable.c

@@ -487,6 +487,7 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
  * rhashtable_walk_init - Initialise an iterator
  * @ht:		Table to walk over
  * @iter:	Hash table Iterator
+ * @gfp:	GFP flags for allocations
  *
  * This function prepares a hash table walk.
  *
@@ -504,14 +505,15 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
  * You must call rhashtable_walk_exit if this function returns
  * successfully.
  */
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter)
+int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
+			 gfp_t gfp)
 {
 	iter->ht = ht;
 	iter->p = NULL;
 	iter->slot = 0;
 	iter->skip = 0;
 
-	iter->walker = kmalloc(sizeof(*iter->walker), GFP_KERNEL);
+	iter->walker = kmalloc(sizeof(*iter->walker), gfp);
 	if (!iter->walker)
 		return -ENOMEM;
 

lib/test_rhashtable.c

@@ -143,7 +143,7 @@ static void test_bucket_stats(struct rhashtable *ht)
 	struct rhashtable_iter hti;
 	struct rhash_head *pos;
 
-	err = rhashtable_walk_init(ht, &hti);
+	err = rhashtable_walk_init(ht, &hti, GFP_KERNEL);
 	if (err) {
 		pr_warn("Test failed: allocation error");
 		return;

net/ipv6/ila/ila_xlat.c

@@ -501,7 +501,8 @@ static int ila_nl_dump_start(struct netlink_callback *cb)
 	struct ila_net *ilan = net_generic(net, ila_net_id);
 	struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args;
 
-	return rhashtable_walk_init(&ilan->rhash_table, &iter->rhiter);
+	return rhashtable_walk_init(&ilan->rhash_table, &iter->rhiter,
+				    GFP_KERNEL);
 }
 
 static int ila_nl_dump_done(struct netlink_callback *cb)

net/netfilter/nft_hash.c

@@ -192,7 +192,7 @@ static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set,
 	u8 genmask = nft_genmask_cur(read_pnet(&set->pnet));
 	int err;
 
-	err = rhashtable_walk_init(&priv->ht, &hti);
+	err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 	iter->err = err;
 	if (err)
 		return;
@@ -248,7 +248,7 @@ static void nft_hash_gc(struct work_struct *work)
 	priv = container_of(work, struct nft_hash, gc_work.work);
 	set  = nft_set_container_of(priv);
 
-	err = rhashtable_walk_init(&priv->ht, &hti);
+	err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 	if (err)
 		goto schedule;
 

net/netlink/af_netlink.c

@@ -2343,7 +2343,8 @@ static int netlink_walk_start(struct nl_seq_iter *iter)
 {
 	int err;
 
-	err = rhashtable_walk_init(&nl_table[iter->link].hash, &iter->hti);
+	err = rhashtable_walk_init(&nl_table[iter->link].hash, &iter->hti,
+				   GFP_KERNEL);
 	if (err) {
 		iter->link = MAX_LINKS;
 		return err;

net/sctp/proc.c

@@ -319,7 +319,8 @@ static int sctp_transport_walk_start(struct seq_file *seq)
 	struct sctp_ht_iter *iter = seq->private;
 	int err;
 
-	err = rhashtable_walk_init(&sctp_transport_hashtable, &iter->hti);
+	err = rhashtable_walk_init(&sctp_transport_hashtable, &iter->hti,
+				   GFP_KERNEL);
 	if (err)
 		return err;