[PATCH bpf-next 3/9] bpf: Refactor the core bpf_task_storage_get logic into a new function

Martin KaFai Lau
2022-10-25T18:46:18Z

This patch creates a new function __bpf_task_storage_get() and
moves the core logic of the existing bpf_task_storage_get()
into this new function. This new function will be shared
by another new helper proto in the latter patch.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
kernel/bpf/bpf_task_storage.c | 44 +++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
index bce50ae03f42..2726435e3eda 100644
--- a/kernel/bpf/bpf_task_storage.c
+++ b/kernel/bpf/bpf_task_storage.c
@@ -227,37 +227,45 @@ static int bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key)
return err;
}

-/* *gfp_flags* is a hidden argument provided by the verifier */
-BPF_CALL_5(bpf_task_storage_get_recur, struct bpf_map *, map, struct task_struct *,
- task, void *, value, u64, flags, gfp_t, gfp_flags)
+/* Called by bpf_task_storage_get*() helpers */
+static void *__bpf_task_storage_get(struct bpf_map *map,
+ struct task_struct *task, void *value,
+ u64 flags, gfp_t gfp_flags)
{
struct bpf_local_storage_data *sdata;

- WARN_ON_ONCE(!bpf_rcu_lock_held());
- if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
- return (unsigned long)NULL;
-
- if (!task)
- return (unsigned long)NULL;
-
- if (!bpf_task_storage_trylock())
- return (unsigned long)NULL;
-
sdata = task_storage_lookup(task, map, true);
if (sdata)
- goto unlock;
+ return sdata->data;

/* only allocate new storage, when the task is refcounted */
if (refcount_read(&task->usage) &&
- (flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
+ (flags & BPF_LOCAL_STORAGE_GET_F_CREATE)) {
sdata = bpf_local_storage_update(
task, (struct bpf_local_storage_map *)map, value,
BPF_NOEXIST, gfp_flags);
+ return IS_ERR(sdata) ? NULL : sdata->data;
+ }

-unlock:
+ return NULL;
+}
+
+/* *gfp_flags* is a hidden argument provided by the verifier */
+BPF_CALL_5(bpf_task_storage_get_recur, struct bpf_map *, map, struct task_struct *,
+ task, void *, value, u64, flags, gfp_t, gfp_flags)
+{
+ void *data;
+
+ WARN_ON_ONCE(!bpf_rcu_lock_held());
+ if (flags & ~BPF_LOCAL_STORAGE_GET_F_CREATE || !task)
+ return (unsigned long)NULL;
+
+ if (!bpf_task_storage_trylock())
+ return (unsigned long)NULL;
+ data = __bpf_task_storage_get(map, task, value, flags,
+ gfp_flags);
bpf_task_storage_unlock();
- return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL :
- (unsigned long)sdata->data;
+ return (unsigned long)data;
}

BPF_CALL_2(bpf_task_storage_delete_recur, struct bpf_map *, map, struct task_struct *,
--
2.30.2