From 3aac1ead5eb6b76f3d2b8d111e6de1c2de23fb34 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Tue, 29 Sep 2020 14:45:50 +0200 Subject: bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In preparation for allowing multiple attachments of freplace programs, move the references to the target program and trampoline into the bpf_tracing_link structure when that is created. To do this atomically, introduce a new mutex in prog->aux to protect writing to the two pointers to target prog and trampoline, and rename the members to make it clear that they are related. With this change, it is no longer possible to attach the same tracing program multiple times (detaching in-between), since the reference from the tracing program to the target disappears on the first attach. However, since the next patch will let the caller supply an attach target, that will also make it possible to attach to the same place multiple times. Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/160138355059.48470.2503076992210324984.stgit@toke.dk --- kernel/bpf/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'kernel/bpf/core.c') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index c4ba45fa4fe1..cda674f1392f 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -99,6 +99,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag INIT_LIST_HEAD_RCU(&fp->aux->ksym.lnode); mutex_init(&fp->aux->used_maps_mutex); + mutex_init(&fp->aux->dst_mutex); return fp; } @@ -255,6 +256,7 @@ void __bpf_prog_free(struct bpf_prog *fp) { if (fp->aux) { mutex_destroy(&fp->aux->used_maps_mutex); + mutex_destroy(&fp->aux->dst_mutex); free_percpu(fp->aux->stats); kfree(fp->aux->poke_tab); kfree(fp->aux); @@ -2138,7 +2140,8 @@ static void bpf_prog_free_deferred(struct work_struct *work) if (aux->prog->has_callchain_buf) put_callchain_buffers(); #endif - bpf_trampoline_put(aux->trampoline); + if (aux->dst_trampoline) + bpf_trampoline_put(aux->dst_trampoline); for (i = 0; i < aux->func_cnt; i++) bpf_jit_free(aux->func[i]); if (aux->func_cnt) { @@ -2154,8 +2157,8 @@ void bpf_prog_free(struct bpf_prog *fp) { struct bpf_prog_aux *aux = fp->aux; - if (aux->linked_prog) - bpf_prog_put(aux->linked_prog); + if (aux->dst_prog) + bpf_prog_put(aux->dst_prog); INIT_WORK(&aux->work, bpf_prog_free_deferred); schedule_work(&aux->work); } -- cgit v1.2.3