From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
This patch uses bpf_mem_cache_alloc/free for allocating and freeing
bpf_local_storage for task and cgroup storage.
The changes are similar to the previous patch. A few things that
worth to mention for bpf_local_storage:
The local_storage is freed when the last selem is deleted.
Before deleting a selem from local_storage, it needs to retrieve the
local_storage->smap because the bpf_selem_unlink_storage_nolock()
may have set it to NULL. Note that local_storage->smap may have
already been NULL when the selem created this local_storage has
been removed. In this case, call_rcu will be used to free the
local_storage.
Also, the bpf_ma (true or false) value is needed before calling
bpf_local_storage_free(). The bpf_ma can either be obtained from
the local_storage->smap (if available) or any of its selem's smap.
A new helper check_storage_bpf_ma() is added to obtain
bpf_ma for a deleting bpf_local_storage.
When bpf_local_storage_alloc getting a reused memory, all
fields are either in the correct values or will be initialized.
'cache[]' must already be all NULLs. 'list' must be empty.
Others will be initialized.
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
---
include/linux/bpf_local_storage.h | 1 +
kernel/bpf/bpf_local_storage.c | 130 ++++++++++++++++++++++++++----
2 files changed, 116 insertions(+), 15 deletions(-)
diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h
index 30efbcab2798..173ec7f43ed1 100644
--- a/include/linux/bpf_local_storage.h
+++ b/include/linux/bpf_local_storage.h
@@ -57,6 +57,7 @@ struct bpf_local_storage_map {
u16 elem_size;
u16 cache_idx;
struct bpf_mem_alloc selem_ma;
+ struct bpf_mem_alloc storage_ma;
bool bpf_ma;
};
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index 309ea727a5cb..dab2ff4c99d9 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -111,33 +111,74 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
return NULL;
}
+/* rcu tasks trace callback for bpf_ma == false */
+static void __bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
+{
+ struct bpf_local_storage *local_storage;
+
+ /* If RCU Tasks Trace grace period implies RCU grace period, do
+ * kfree(), else do kfree_rcu().
+ */
+ local_storage = container_of(rcu, struct bpf_local_storage, rcu);
+ if (rcu_trace_implies_rcu_gp())
+ kfree(local_storage);
+ else
+ kfree_rcu(local_storage, rcu);
+}
+
static void bpf_local_storage_free_rcu(struct rcu_head *rcu)
{
struct bpf_local_storage *local_storage;
local_storage = container_of(rcu, struct bpf_local_storage, rcu);
- kfree(local_storage);
+ bpf_mem_cache_raw_free(local_storage);
}
static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
{
- /* If RCU Tasks Trace grace period implies RCU grace period, do
- * kfree(), else do kfree_rcu().
- */
if (rcu_trace_implies_rcu_gp())
bpf_local_storage_free_rcu(rcu);
else
call_rcu(rcu, bpf_local_storage_free_rcu);
}
+/* Handle bpf_ma == false */
+static void __bpf_local_storage_free(struct bpf_local_storage *local_storage,
+ bool vanilla_rcu)
+{
+ if (vanilla_rcu)
+ kfree_rcu(local_storage, rcu);
+ else
+ call_rcu_tasks_trace(&local_storage->rcu,
+ __bpf_local_storage_free_trace_rcu);
+}
+
static void bpf_local_storage_free(struct bpf_local_storage *local_storage,
- bool reuse_now)
+ struct bpf_local_storage_map *smap,
+ bool bpf_ma, bool reuse_now)
{
- if (!reuse_now)
+ if (!bpf_ma) {
+ __bpf_local_storage_free(local_storage, reuse_now);
+ return;
+ }
+
+ if (!reuse_now) {
call_rcu_tasks_trace(&local_storage->rcu,
bpf_local_storage_free_trace_rcu);
- else
+ return;
+ }
+
+ if (smap) {
+ migrate_disable();
+ bpf_mem_cache_free(&smap->storage_ma, local_storage);
+ migrate_enable();
+ } else {
+ /* smap could be NULL if the selem that triggered
+ * this 'local_storage' creation had been long gone.
+ * In this case, directly do call_rcu().
+ */
call_rcu(&local_storage->rcu, bpf_local_storage_free_rcu);
+ }
}
/* rcu tasks trace callback for bpf_ma == false */
@@ -260,11 +301,47 @@ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_stor
return free_local_storage;
}
+static bool check_storage_bpf_ma(struct bpf_local_storage *local_storage,
+ struct bpf_local_storage_map *storage_smap,
+ struct bpf_local_storage_elem *selem)
+{
+
+ struct bpf_local_storage_map *selem_smap;
+
+ /* local_storage->smap may be NULL. If it is, get the bpf_ma
+ * from any selem in the local_storage->list. The bpf_ma of all
+ * local_storage and selem should have the same value
+ * for the same map type.
+ *
+ * If the local_storage->list is already empty, the caller will not
+ * care about the bpf_ma value also because the caller is not
+ * responsibile to free the local_storage.
+ */
+
+ if (storage_smap)
+ return storage_smap->bpf_ma;
+
+ if (!selem) {
+ struct hlist_node *n;
+
+ n = rcu_dereference_check(hlist_first_rcu(&local_storage->list),
+ bpf_rcu_lock_held());
+ if (!n)
+ return false;
+
+ selem = hlist_entry(n, struct bpf_local_storage_elem, snode);
+ }
+ selem_smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
+
+ return selem_smap->bpf_ma;
+}
+
static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
bool reuse_now)
{
+ struct bpf_local_storage_map *storage_smap;
struct bpf_local_storage *local_storage;
- bool free_local_storage = false;
+ bool bpf_ma, free_local_storage = false;
unsigned long flags;
if (unlikely(!selem_linked_to_storage_lockless(selem)))
@@ -273,6 +350,10 @@ static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
local_storage = rcu_dereference_check(selem->local_storage,
bpf_rcu_lock_held());
+ storage_smap = rcu_dereference_check(local_storage->smap,
+ bpf_rcu_lock_held());
+ bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, selem);
+
raw_spin_lock_irqsave(&local_storage->lock, flags);
if (likely(selem_linked_to_storage(selem)))
free_local_storage = bpf_selem_unlink_storage_nolock(
@@ -280,7 +361,7 @@ static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
if (free_local_storage)
- bpf_local_storage_free(local_storage, reuse_now);
+ bpf_local_storage_free(local_storage, storage_smap, bpf_ma, reuse_now);
}
void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
@@ -400,8 +481,15 @@ int bpf_local_storage_alloc(void *owner,
if (err)
return err;
- storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
- gfp_flags | __GFP_NOWARN);
+ if (smap->bpf_ma) {
+ migrate_disable();
+ storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags);
+ migrate_enable();
+ } else {
+ storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
+ gfp_flags | __GFP_NOWARN);
+ }
+
if (!storage) {
err = -ENOMEM;
goto uncharge;
@@ -447,7 +535,7 @@ int bpf_local_storage_alloc(void *owner,
return 0;
uncharge:
- bpf_local_storage_free(storage, true);
+ bpf_local_storage_free(storage, smap, smap->bpf_ma, true);
mem_uncharge(smap, owner, sizeof(*storage));
return err;
}
@@ -660,11 +748,15 @@ int bpf_local_storage_map_check_btf(const struct bpf_map *map,
void bpf_local_storage_destroy(struct bpf_local_storage *local_storage)
{
+ struct bpf_local_storage_map *storage_smap;
struct bpf_local_storage_elem *selem;
- bool free_storage = false;
+ bool bpf_ma, free_storage = false;
struct hlist_node *n;
unsigned long flags;
+ storage_smap = rcu_dereference_check(local_storage->smap, bpf_rcu_lock_held());
+ bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, NULL);
+
/* Neither the bpf_prog nor the bpf_map's syscall
* could be modifying the local_storage->list now.
* Thus, no elem can be added to or deleted from the
@@ -692,7 +784,7 @@ void bpf_local_storage_destroy(struct bpf_local_storage *local_storage)
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
if (free_storage)
- bpf_local_storage_free(local_storage, true);
+ bpf_local_storage_free(local_storage, storage_smap, bpf_ma, true);
}
u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map)
@@ -755,6 +847,12 @@ bpf_local_storage_map_alloc(union bpf_attr *attr,
err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false);
if (err)
goto free_smap;
+
+ err = bpf_mem_alloc_init(&smap->storage_ma, sizeof(struct bpf_local_storage), false);
+ if (err) {
+ bpf_mem_alloc_destroy(&smap->selem_ma);
+ goto free_smap;
+ }
}
smap->cache_idx = bpf_local_storage_cache_idx_get(cache);
@@ -829,8 +927,10 @@ void bpf_local_storage_map_free(struct bpf_map *map,
*/
synchronize_rcu();
- if (smap->bpf_ma)
+ if (smap->bpf_ma) {
bpf_mem_alloc_destroy(&smap->selem_ma);
+ bpf_mem_alloc_destroy(&smap->storage_ma);
+ }
kvfree(smap->buckets);
bpf_map_area_free(smap);
}
--
2.34.1
