Re: [PATCH bpf-next 1/4] bpf: enable task local storage for tracing programs

On Mon, Jan 11, 2021 at 03:41:26PM -0800, Song Liu wrote:

quoted

On Jan 11, 2021, at 10:56 AM, Martin Lau [off-list ref] wrote:

On Fri, Jan 08, 2021 at 03:19:47PM -0800, Song Liu wrote:

[ ... ]

quoted

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.

Do you mean we allow bpf_sk_storage_get_tracing() and 
bpf_sk_storage_delete_tracing() in irq context? Like

Right.

However, after another thought, may be lets skip that for now
till a use case comes up and a test can be written.