On Fri, Jan 08, 2021 at 03:19:47PM -0800, Song Liu wrote:
[ ... ]
> diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
> index dd5aedee99e73..9bd47ad2b26f1 100644
> --- a/kernel/bpf/bpf_local_storage.c
> +++ b/kernel/bpf/bpf_local_storage.c
> @@ -140,17 +140,18 @@ static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem)
> {
> struct bpf_local_storage *local_storage;
> bool free_local_storage = false;
> + unsigned long flags;
>
> if (unlikely(!selem_linked_to_storage(selem)))
> /* selem has already been unlinked from sk */
> return;
>
> local_storage = rcu_dereference(selem->local_storage);
> - raw_spin_lock_bh(&local_storage->lock);
> + raw_spin_lock_irqsave(&local_storage->lock, flags);
It will be useful to have a few words in commit message on this change
for future reference purpose.
Please also remove the in_irq() check from bpf_sk_storage.c
to avoid confusion in the future. It probably should
be in a separate patch.
[ ... ]
> diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
> index 4ef1959a78f27..f654b56907b69 100644
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 7425b3224891d..3d65c8ebfd594 100644
[ ... ]
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -96,6 +96,7 @@
> #include <linux/kasan.h>
> #include <linux/scs.h>
> #include <linux/io_uring.h>
> +#include <linux/bpf.h>
>
> #include <asm/pgalloc.h>
> #include <linux/uaccess.h>
> @@ -734,6 +735,7 @@ void __put_task_struct(struct task_struct *tsk)
> cgroup_free(tsk);
> task_numa_free(tsk, true);
> security_task_free(tsk);
> + bpf_task_storage_free(tsk);
> exit_creds(tsk);
If exit_creds() is traced by a bpf and this bpf is doing
bpf_task_storage_get(..., BPF_LOCAL_STORAGE_GET_F_CREATE),
new task storage will be created after bpf_task_storage_free().
I recalled there was an earlier discussion with KP and KP mentioned
BPF_LSM will not be called with a task that is going away.
It seems enabling bpf task storage in bpf tracing will break
this assumption and needs to be addressed?
