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authorAndrii Nakryiko2019-11-17 09:28:03 -0800
committerDaniel Borkmann2019-11-18 11:41:59 +0100
commit85192dbf4de08795afe2b88e52a36fc6abfc3dba (patch)
tree52379ced52c2c2ed5f023073a1aeeb52779e376d /kernel/bpf
parent1e0bd5a091e5d9e0f1d5b0e6329b87bb1792f784 (diff)
bpf: Convert bpf_prog refcnt to atomic64_t
Similarly to bpf_map's refcnt/usercnt, convert bpf_prog's refcnt to atomic64 and remove artificial 32k limit. This allows to make bpf_prog's refcounting non-failing, simplifying logic of users of bpf_prog_add/bpf_prog_inc. Validated compilation by running allyesconfig kernel build. Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191117172806.2195367-3-andriin@fb.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/inode.c5
-rw-r--r--kernel/bpf/syscall.c30
2 files changed, 12 insertions, 23 deletions
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 2f17f24258dc..ecf42bec38c0 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -31,7 +31,7 @@ static void *bpf_any_get(void *raw, enum bpf_type type)
{
switch (type) {
case BPF_TYPE_PROG:
- raw = bpf_prog_inc(raw);
+ bpf_prog_inc(raw);
break;
case BPF_TYPE_MAP:
bpf_map_inc_with_uref(raw);
@@ -534,7 +534,8 @@ static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type
if (!bpf_prog_get_ok(prog, &type, false))
return ERR_PTR(-EINVAL);
- return bpf_prog_inc(prog);
+ bpf_prog_inc(prog);
+ return prog;
}
struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 20030751b7a2..52fe4bacb330 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1339,7 +1339,7 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred)
static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
{
- if (atomic_dec_and_test(&prog->aux->refcnt)) {
+ if (atomic64_dec_and_test(&prog->aux->refcnt)) {
perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0);
/* bpf_prog_free_id() must be called first */
bpf_prog_free_id(prog, do_idr_lock);
@@ -1445,16 +1445,9 @@ static struct bpf_prog *____bpf_prog_get(struct fd f)
return f.file->private_data;
}
-/* prog's refcnt limit */
-#define BPF_MAX_REFCNT 32768
-
-struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i)
+void bpf_prog_add(struct bpf_prog *prog, int i)
{
- if (atomic_add_return(i, &prog->aux->refcnt) > BPF_MAX_REFCNT) {
- atomic_sub(i, &prog->aux->refcnt);
- return ERR_PTR(-EBUSY);
- }
- return prog;
+ atomic64_add(i, &prog->aux->refcnt);
}
EXPORT_SYMBOL_GPL(bpf_prog_add);
@@ -1465,13 +1458,13 @@ void bpf_prog_sub(struct bpf_prog *prog, int i)
* path holds a reference to the program, thus atomic_sub() can
* be safely used in such cases!
*/
- WARN_ON(atomic_sub_return(i, &prog->aux->refcnt) == 0);
+ WARN_ON(atomic64_sub_return(i, &prog->aux->refcnt) == 0);
}
EXPORT_SYMBOL_GPL(bpf_prog_sub);
-struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
+void bpf_prog_inc(struct bpf_prog *prog)
{
- return bpf_prog_add(prog, 1);
+ atomic64_inc(&prog->aux->refcnt);
}
EXPORT_SYMBOL_GPL(bpf_prog_inc);
@@ -1480,12 +1473,7 @@ struct bpf_prog *bpf_prog_inc_not_zero(struct bpf_prog *prog)
{
int refold;
- refold = atomic_fetch_add_unless(&prog->aux->refcnt, 1, 0);
-
- if (refold >= BPF_MAX_REFCNT) {
- __bpf_prog_put(prog, false);
- return ERR_PTR(-EBUSY);
- }
+ refold = atomic64_fetch_add_unless(&prog->aux->refcnt, 1, 0);
if (!refold)
return ERR_PTR(-ENOENT);
@@ -1523,7 +1511,7 @@ static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type,
goto out;
}
- prog = bpf_prog_inc(prog);
+ bpf_prog_inc(prog);
out:
fdput(f);
return prog;
@@ -1714,7 +1702,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
prog->orig_prog = NULL;
prog->jited = 0;
- atomic_set(&prog->aux->refcnt, 1);
+ atomic64_set(&prog->aux->refcnt, 1);
prog->gpl_compatible = is_gpl ? 1 : 0;
if (bpf_prog_is_dev_bound(prog->aux)) {