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Message-Id: <E1baJ2O-00030u-FE@gondolin.me.apana.org.au>
Date: Thu, 18 Aug 2016 16:50:56 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: "David S. Miller" <davem@...emloft.net>,
Thomas Graf <tgraf@...g.ch>, netdev@...r.kernel.org
Subject: [PATCH 1/3] rhashtable: Remove GFP flag from rhashtable_walk_init
The commit 8f6fd83c6c5ec66a4a70c728535ddcdfef4f3697 ("rhashtable:
accept GFP flags in rhashtable_walk_init") added a GFP flag argument
to rhashtable_walk_init because some users wish to use the walker
in an unsleepable context.
In fact we don't need to allocate memory in rhashtable_walk_init
at all. The walker is always paired with an iterator so we could
just stash ourselves there.
This patch does that by introducing a new enter function to replace
the existing init function. This way we don't have to churn all
the existing users again.
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
---
include/linux/rhashtable.h | 14 ++++++++++---
lib/rhashtable.c | 46 +++++++++++++++++----------------------------
2 files changed, 29 insertions(+), 31 deletions(-)
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 3eef080..8b72ee7 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -173,7 +173,7 @@ struct rhashtable_walker {
struct rhashtable_iter {
struct rhashtable *ht;
struct rhash_head *p;
- struct rhashtable_walker *walker;
+ struct rhashtable_walker walker;
unsigned int slot;
unsigned int skip;
};
@@ -346,8 +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,
- gfp_t gfp);
+void rhashtable_walk_enter(struct rhashtable *ht,
+ struct rhashtable_iter *iter);
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);
@@ -906,4 +906,12 @@ static inline int rhashtable_replace_fast(
return err;
}
+/* Obsolete function, do not use in new code. */
+static inline int rhashtable_walk_init(struct rhashtable *ht,
+ struct rhashtable_iter *iter, gfp_t gfp)
+{
+ rhashtable_walk_enter(ht, iter);
+ return 0;
+}
+
#endif /* _LINUX_RHASHTABLE_H */
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 5d845ff..5b0a2b3 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -484,10 +484,9 @@ exit:
EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
/**
- * rhashtable_walk_init - Initialise an iterator
+ * rhashtable_walk_enter - Initialise an iterator
* @ht: Table to walk over
* @iter: Hash table Iterator
- * @gfp: GFP flags for allocations
*
* This function prepares a hash table walk.
*
@@ -502,30 +501,22 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
* This function may sleep so you must not call it from interrupt
* context or with spin locks held.
*
- * You must call rhashtable_walk_exit if this function returns
- * successfully.
+ * You must call rhashtable_walk_exit after this function returns.
*/
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
- gfp_t gfp)
+void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter)
{
iter->ht = ht;
iter->p = NULL;
iter->slot = 0;
iter->skip = 0;
- iter->walker = kmalloc(sizeof(*iter->walker), gfp);
- if (!iter->walker)
- return -ENOMEM;
-
spin_lock(&ht->lock);
- iter->walker->tbl =
+ iter->walker.tbl =
rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock));
- list_add(&iter->walker->list, &iter->walker->tbl->walkers);
+ list_add(&iter->walker.list, &iter->walker.tbl->walkers);
spin_unlock(&ht->lock);
-
- return 0;
}
-EXPORT_SYMBOL_GPL(rhashtable_walk_init);
+EXPORT_SYMBOL_GPL(rhashtable_walk_enter);
/**
* rhashtable_walk_exit - Free an iterator
@@ -536,10 +527,9 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_init);
void rhashtable_walk_exit(struct rhashtable_iter *iter)
{
spin_lock(&iter->ht->lock);
- if (iter->walker->tbl)
- list_del(&iter->walker->list);
+ if (iter->walker.tbl)
+ list_del(&iter->walker.list);
spin_unlock(&iter->ht->lock);
- kfree(iter->walker);
}
EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
@@ -565,12 +555,12 @@ int rhashtable_walk_start(struct rhashtable_iter *iter)
rcu_read_lock();
spin_lock(&ht->lock);
- if (iter->walker->tbl)
- list_del(&iter->walker->list);
+ if (iter->walker.tbl)
+ list_del(&iter->walker.list);
spin_unlock(&ht->lock);
- if (!iter->walker->tbl) {
- iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht);
+ if (!iter->walker.tbl) {
+ iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht);
return -EAGAIN;
}
@@ -592,7 +582,7 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_start);
*/
void *rhashtable_walk_next(struct rhashtable_iter *iter)
{
- struct bucket_table *tbl = iter->walker->tbl;
+ struct bucket_table *tbl = iter->walker.tbl;
struct rhashtable *ht = iter->ht;
struct rhash_head *p = iter->p;
@@ -625,8 +615,8 @@ next:
/* Ensure we see any new tables. */
smp_rmb();
- iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht);
- if (iter->walker->tbl) {
+ iter->walker.tbl = rht_dereference_rcu(tbl->future_tbl, ht);
+ if (iter->walker.tbl) {
iter->slot = 0;
iter->skip = 0;
return ERR_PTR(-EAGAIN);
@@ -646,7 +636,7 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
__releases(RCU)
{
struct rhashtable *ht;
- struct bucket_table *tbl = iter->walker->tbl;
+ struct bucket_table *tbl = iter->walker.tbl;
if (!tbl)
goto out;
@@ -655,9 +645,9 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
spin_lock(&ht->lock);
if (tbl->rehash < tbl->size)
- list_add(&iter->walker->list, &tbl->walkers);
+ list_add(&iter->walker.list, &tbl->walkers);
else
- iter->walker->tbl = NULL;
+ iter->walker.tbl = NULL;
spin_unlock(&ht->lock);
iter->p = NULL;
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