Re: [PATCH v3 1/3] bpf: propagate cb_access from freplace programs
From: Alexei Starovoitov <hidden>
Date: 2026-09-20 17:06:42
Also in:
bpf, linux-kselftest, lkml, stable
On Mon, Sep 21, 2026 at 12:32 AM Weiming Shi [off-list ref] wrote:
Cc: stable@vger.kernel.org
Fixes: be8704ff07d2 ("bpf: Introduce dynamic program extensions")That shouldn't go to stable. Loading an EXT prog takes CAP_BPF + CAP_NET_ADMIN + CAP_PERFMON. [...]
+ if (prog->type == BPF_PROG_TYPE_EXT && READ_ONCE(prog->cb_access)) {
+ WRITE_ONCE(tgt_prog->cb_access, true);
+ /* Drain runs that observed cb_access=false before enabling freplace. */
+ synchronize_rcu();
+ }tc doesn't look at cb_access at all, yet every tc freplace that touches cb[] now waits for an RCU grace period in attach. This is a separate issue from the LWT one. Patch 2 resets the cb after the run whether the prog has cb_access or not, so it doesn't depend on this patch. Pls drop it from this series.