From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
This patch uses bpf_mem_cache_alloc/free for allocating and freeing
bpf_local_storage.
The changes are similar to the previous patch when switching
bpf_local_storage_elem to bpf_mem_cache_alloc/free.
A few things that worth to mention for bpf_local_storage:
The local_storage is deleted 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.
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 | 50 ++++++++++++++++++++++++++-----
2 files changed, 43 insertions(+), 8 deletions(-)
diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h
index 550da364c8f9..ed35ce238b3d 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;
};
struct bpf_local_storage_data {
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index 228abb6b6e64..7f3ad118735e 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -111,7 +111,7 @@ 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)
@@ -126,13 +126,30 @@ static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
}
static void bpf_local_storage_free(struct bpf_local_storage *local_storage,
+ struct bpf_local_storage_map *smap,
bool reuse_now)
{
- if (!reuse_now)
+ if (!reuse_now) {
call_rcu_tasks_trace(&local_storage->rcu,
bpf_local_storage_free_trace_rcu);
- else
+ return;
+ }
+
+ if (smap) {
+ /* Instead of using the vanilla call_rcu(),
+ * bpf_mem_cache_free should be able to reuse local_storage
+ * immediately.
+ */
+ 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);
+ }
}
static void bpf_selem_free_rcu(struct rcu_head *rcu)
@@ -230,6 +247,7 @@ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_stor
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;
unsigned long flags;
@@ -240,6 +258,8 @@ 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());
raw_spin_lock_irqsave(&local_storage->lock, flags);
if (likely(selem_linked_to_storage(selem)))
free_local_storage = bpf_selem_unlink_storage_nolock(
@@ -247,7 +267,8 @@ 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,
+ reuse_now);
}
void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
@@ -367,8 +388,10 @@ int bpf_local_storage_alloc(void *owner,
if (err)
return err;
- storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
- gfp_flags | __GFP_NOWARN);
+ migrate_disable();
+ storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags);
+ migrate_enable();
+
if (!storage) {
err = -ENOMEM;
goto uncharge;
@@ -414,7 +437,7 @@ int bpf_local_storage_alloc(void *owner,
return 0;
uncharge:
- bpf_local_storage_free(storage, true);
+ bpf_local_storage_free(storage, smap, true);
mem_uncharge(smap, owner, sizeof(*storage));
return err;
}
@@ -627,11 +650,15 @@ 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;
struct hlist_node *n;
unsigned long flags;
+ storage_smap = rcu_dereference_check(local_storage->smap,
+ bpf_rcu_lock_held());
+
/* 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
@@ -659,7 +686,7 @@ 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, true);
}
u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map)
@@ -710,6 +737,12 @@ bpf_local_storage_map_alloc(union bpf_attr *attr,
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);
return &smap->map;
@@ -783,6 +816,7 @@ void bpf_local_storage_map_free(struct bpf_map *map,
synchronize_rcu();
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
