[PATCH bpf-next v2 06/15] bpf: offload: factor out netdev checking at allocation time

[Jakub Kicinski]

Add a helper to check if netdev could be found and whether it
has .ndo_bpf callback.  There is no need to check the callback
every time it's invoked, ndos can't reasonably be swapped for
a set without .ndp_bpf while program is loaded.

bpf_dev_offload_check() will also be used by map offload.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Reviewed-by: Quentin Monnet <quentin.mon...@netronome.com>
---
 kernel/bpf/offload.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index 001ddfde7874..cdd1e19a668b 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -30,9 +30,19 @@
 static DECLARE_RWSEM(bpf_devs_lock);
 static LIST_HEAD(bpf_prog_offload_devs);
 
+static int bpf_dev_offload_check(struct net_device *netdev)
+{
+       if (!netdev)
+               return -EINVAL;
+       if (!netdev->netdev_ops->ndo_bpf)
+               return -EOPNOTSUPP;
+       return 0;
+}
+
 int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
 {
        struct bpf_prog_offload *offload;
+       int err;
 
        if (attr->prog_type != BPF_PROG_TYPE_SCHED_CLS &&
            attr->prog_type != BPF_PROG_TYPE_XDP)
@@ -49,12 +59,15 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union 
bpf_attr *attr)
 
        offload->netdev = dev_get_by_index(current->nsproxy->net_ns,
                                           attr->prog_ifindex);
-       if (!offload->netdev)
-               goto err_free;
+       err = bpf_dev_offload_check(offload->netdev);
+       if (err)
+               goto err_maybe_put;
 
        down_write(&bpf_devs_lock);
-       if (offload->netdev->reg_state != NETREG_REGISTERED)
+       if (offload->netdev->reg_state != NETREG_REGISTERED) {
+               err = -EINVAL;
                goto err_unlock;
+       }
        prog->aux->offload = offload;
        list_add_tail(&offload->offloads, &bpf_prog_offload_devs);
        dev_put(offload->netdev);
@@ -63,10 +76,11 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union 
bpf_attr *attr)
        return 0;
 err_unlock:
        up_write(&bpf_devs_lock);
-       dev_put(offload->netdev);
-err_free:
+err_maybe_put:
+       if (offload->netdev)
+               dev_put(offload->netdev);
        kfree(offload);
-       return -EINVAL;
+       return err;
 }
 
 static int __bpf_offload_ndo(struct bpf_prog *prog, enum bpf_netdev_command 
cmd,
@@ -80,8 +94,6 @@ static int __bpf_offload_ndo(struct bpf_prog *prog, enum 
bpf_netdev_command cmd,
        if (!offload)
                return -ENODEV;
        netdev = offload->netdev;
-       if (!netdev->netdev_ops->ndo_bpf)
-               return -EOPNOTSUPP;
 
        data->command = cmd;
 
-- 
2.15.1