diff options
| author | Mykyta Yatsenko <yatsenko@meta.com> | 2025-10-26 20:38:52 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-10-27 09:56:27 -0700 |
| commit | 2c52e8943a437af6093d8b0f0920f1764f0e5f64 (patch) | |
| tree | 68e993ce0973cc679de4fb7087f64068b77b22f8 | |
| parent | d869d56ca848415b1169ba08b4f92a32968de8a2 (diff) | |
bpf: dispatch to sleepable file dynptr
File dynptr reads may sleep when the requested folios are not in
the page cache. To avoid sleeping in non-sleepable contexts while still
supporting valid sleepable use, given that dynptrs are non-sleepable by
default, enable sleeping only when bpf_dynptr_from_file() is invoked
from a sleepable context.
This change:
* Introduces a sleepable constructor: bpf_dynptr_from_file_sleepable()
* Override non-sleepable constructor with sleepable if it's always
called in sleepable context
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251026203853.135105-10-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | include/linux/bpf.h | 3 | ||||
| -rw-r--r-- | kernel/bpf/helpers.c | 5 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 10 |
3 files changed, 15 insertions, 3 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 14f800773997..a47d67db3be5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -670,6 +670,9 @@ static inline bool bpf_map_has_internal_structs(struct bpf_map *map) void bpf_map_free_internal_structs(struct bpf_map *map, void *obj); +int bpf_dynptr_from_file_sleepable(struct file *file, u32 flags, + struct bpf_dynptr *ptr__uninit); + extern const struct bpf_map_ops bpf_map_offload_ops; /* bpf_type_flag contains a set of flags that are applicable to the values of diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 99a7def0b978..930e132f440f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -4336,6 +4336,11 @@ __bpf_kfunc int bpf_dynptr_from_file(struct file *file, u32 flags, struct bpf_dy return make_file_dynptr(file, flags, false, (struct bpf_dynptr_kern *)ptr__uninit); } +int bpf_dynptr_from_file_sleepable(struct file *file, u32 flags, struct bpf_dynptr *ptr__uninit) +{ + return make_file_dynptr(file, flags, true, (struct bpf_dynptr_kern *)ptr__uninit); +} + __bpf_kfunc int bpf_dynptr_file_discard(struct bpf_dynptr *dynptr) { struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)dynptr; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 61589be91c65..542e23fb19c7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3124,7 +3124,8 @@ struct bpf_kfunc_btf_tab { u32 nr_descs; }; -static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc); +static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc, + int insn_idx); static int kfunc_desc_cmp_by_id_off(const void *a, const void *b) { @@ -21869,7 +21870,7 @@ static int fixup_call_args(struct bpf_verifier_env *env) } /* replace a generic kfunc with a specialized version if necessary */ -static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc) +static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc, int insn_idx) { struct bpf_prog *prog = env->prog; bool seen_direct_write; @@ -21904,6 +21905,9 @@ static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc } else if (func_id == special_kfunc_list[KF_bpf_remove_dentry_xattr]) { if (bpf_lsm_has_d_inode_locked(prog)) addr = (unsigned long)bpf_remove_dentry_xattr_locked; + } else if (func_id == special_kfunc_list[KF_bpf_dynptr_from_file]) { + if (!env->insn_aux_data[insn_idx].non_sleepable) + addr = (unsigned long)bpf_dynptr_from_file_sleepable; } set_imm: @@ -21963,7 +21967,7 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return -EFAULT; } - err = specialize_kfunc(env, desc); + err = specialize_kfunc(env, desc, insn_idx); if (err) return err; |