From: David Vernet Date: Tue, 11 Apr 2023 04:16:32 +0000 (-0500) Subject: bpf: Remove bpf_cgroup_kptr_get() kfunc X-Git-Tag: v6.4-rc1~77^2~118^2~14 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=6499fe6edc4fd5b91aed4d5cd84bd113e1c58d5f;p=tomoyo%2Ftomoyo-test1.git bpf: Remove bpf_cgroup_kptr_get() kfunc Now that bpf_cgroup_acquire() is KF_RCU | KF_RET_NULL, bpf_cgroup_kptr_get() is redundant. Let's remove it, and update selftests to instead use bpf_cgroup_acquire() where appropriate. The next patch will update the BPF documentation to not mention bpf_cgroup_kptr_get(). Signed-off-by: David Vernet Link: https://lore.kernel.org/r/20230411041633.179404-2-void@manifault.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 71f0604bdc97..f04e60a4847f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2041,37 +2041,6 @@ __bpf_kfunc struct cgroup *bpf_cgroup_acquire(struct cgroup *cgrp) } /** - * bpf_cgroup_kptr_get - Acquire a reference on a struct cgroup kptr. A cgroup - * kptr acquired by this kfunc which is not subsequently stored in a map, must - * be released by calling bpf_cgroup_release(). - * @cgrpp: A pointer to a cgroup kptr on which a reference is being acquired. - */ -__bpf_kfunc struct cgroup *bpf_cgroup_kptr_get(struct cgroup **cgrpp) -{ - struct cgroup *cgrp; - - rcu_read_lock(); - /* Another context could remove the cgroup from the map and release it - * at any time, including after we've done the lookup above. This is - * safe because we're in an RCU read region, so the cgroup is - * guaranteed to remain valid until at least the rcu_read_unlock() - * below. - */ - cgrp = READ_ONCE(*cgrpp); - - if (cgrp && !cgroup_tryget(cgrp)) - /* If the cgroup had been removed from the map and freed as - * described above, cgroup_tryget() will return false. The - * cgroup will be freed at some point after the current RCU gp - * has ended, so just return NULL to the user. - */ - cgrp = NULL; - rcu_read_unlock(); - - return cgrp; -} - -/** * bpf_cgroup_release - Release the reference acquired on a cgroup. * If this kfunc is invoked in an RCU read region, the cgroup is guaranteed to * not be freed until the current grace period has ended, even if its refcount @@ -2314,7 +2283,6 @@ BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL) #ifdef CONFIG_CGROUPS BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL) -BTF_ID_FLAGS(func, bpf_cgroup_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cgroup_release, KF_RELEASE) BTF_ID_FLAGS(func, bpf_cgroup_ancestor, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cgroup_from_id, KF_ACQUIRE | KF_RET_NULL) diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h index b0e279f4652b..22914a70db54 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h @@ -21,10 +21,11 @@ struct hash_map { } __cgrps_kfunc_map SEC(".maps"); struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; -struct cgroup *bpf_cgroup_kptr_get(struct cgroup **pp) __ksym; void bpf_cgroup_release(struct cgroup *p) __ksym; struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym; struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym; +void bpf_rcu_read_lock(void) __ksym; +void bpf_rcu_read_unlock(void) __ksym; static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp) { diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c index 49347f12de39..0fa564a5cc5b 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c @@ -134,59 +134,6 @@ int BPF_PROG(cgrp_kfunc_acquire_unreleased, struct cgroup *cgrp, const char *pat } SEC("tp_btf/cgroup_mkdir") -__failure __msg("arg#0 expected pointer to map value") -int BPF_PROG(cgrp_kfunc_get_non_kptr_param, struct cgroup *cgrp, const char *path) -{ - struct cgroup *kptr; - - /* Cannot use bpf_cgroup_kptr_get() on a non-kptr, even on a valid cgroup. */ - kptr = bpf_cgroup_kptr_get(&cgrp); - if (!kptr) - return 0; - - bpf_cgroup_release(kptr); - - return 0; -} - -SEC("tp_btf/cgroup_mkdir") -__failure __msg("arg#0 expected pointer to map value") -int BPF_PROG(cgrp_kfunc_get_non_kptr_acquired, struct cgroup *cgrp, const char *path) -{ - struct cgroup *kptr, *acquired; - - acquired = bpf_cgroup_acquire(cgrp); - if (!acquired) - return 0; - - /* Cannot use bpf_cgroup_kptr_get() on a non-map-value, even if the kptr was acquired. */ - kptr = bpf_cgroup_kptr_get(&acquired); - bpf_cgroup_release(acquired); - if (!kptr) - return 0; - - bpf_cgroup_release(kptr); - - return 0; -} - -SEC("tp_btf/cgroup_mkdir") -__failure __msg("arg#0 expected pointer to map value") -int BPF_PROG(cgrp_kfunc_get_null, struct cgroup *cgrp, const char *path) -{ - struct cgroup *kptr; - - /* Cannot use bpf_cgroup_kptr_get() on a NULL pointer. */ - kptr = bpf_cgroup_kptr_get(NULL); - if (!kptr) - return 0; - - bpf_cgroup_release(kptr); - - return 0; -} - -SEC("tp_btf/cgroup_mkdir") __failure __msg("Unreleased reference") int BPF_PROG(cgrp_kfunc_xchg_unreleased, struct cgroup *cgrp, const char *path) { @@ -207,8 +154,8 @@ int BPF_PROG(cgrp_kfunc_xchg_unreleased, struct cgroup *cgrp, const char *path) } SEC("tp_btf/cgroup_mkdir") -__failure __msg("Unreleased reference") -int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup *cgrp, const char *path) +__failure __msg("must be referenced or trusted") +int BPF_PROG(cgrp_kfunc_rcu_get_release, struct cgroup *cgrp, const char *path) { struct cgroup *kptr; struct __cgrps_kfunc_map_value *v; @@ -217,11 +164,12 @@ int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup *cgrp, const char *path) if (!v) return 0; - kptr = bpf_cgroup_kptr_get(&v->cgrp); - if (!kptr) - return 0; - - /* Kptr acquired above is never released. */ + bpf_rcu_read_lock(); + kptr = v->cgrp; + if (kptr) + /* Can't release a cgroup kptr stored in a map. */ + bpf_cgroup_release(kptr); + bpf_rcu_read_unlock(); return 0; } diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c index e9dbd1af05a7..5354455a01be 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c @@ -126,13 +126,11 @@ int BPF_PROG(test_cgrp_get_release, struct cgroup *cgrp, const char *path) return 0; } - kptr = bpf_cgroup_kptr_get(&v->cgrp); - if (!kptr) { + bpf_rcu_read_lock(); + kptr = v->cgrp; + if (!kptr) err = 3; - return 0; - } - - bpf_cgroup_release(kptr); + bpf_rcu_read_unlock(); return 0; }