Commit e0d3974a authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Daniel Borkmann
Browse files

bpf: offload: don't require rtnl for dev list manipulation 



We don't need the RTNL lock for all operations on offload state.
We only need to hold it around ndo calls.  The device offload
initialization doesn't require it.  The soon-to-come querying
of the offload info will only need it partially.  We will also
be able to remove the waitqueue in following patches.

Use struct rw_semaphore because map offload will require sleeping
with the semaphore held for read.

Suggested-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent fb982666

kernel/bpf/offload.c

+24 −10
Original line number Diff line number Diff line
@@ -20,13 +20,16 @@ 
#include <linux/netdevice.h>

#include <linux/printk.h>

#include <linux/rtnetlink.h>

#include <linux/rwsem.h>



/* protected by RTNL */

/* Protects bpf_prog_offload_devs and offload members of all progs.

 * RTNL lock cannot be taken when holding this lock.

 */

static DECLARE_RWSEM(bpf_devs_lock);

static LIST_HEAD(bpf_prog_offload_devs);



int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)

{

	struct net *net = current->nsproxy->net_ns;

	struct bpf_dev_offload *offload;



	if (attr->prog_type != BPF_PROG_TYPE_SCHED_CLS &&
@@ -43,19 +46,26 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr) 
	offload->prog = prog;

	init_waitqueue_head(&offload->verifier_done);



	rtnl_lock();

	offload->netdev = __dev_get_by_index(net, attr->prog_ifindex);

	if (!offload->netdev) {

		rtnl_unlock();

		kfree(offload);

		return -EINVAL;

	}

	offload->netdev = dev_get_by_index(current->nsproxy->net_ns,

					   attr->prog_ifindex);

	if (!offload->netdev)

		goto err_free;



	down_write(&bpf_devs_lock);

	if (offload->netdev->reg_state != NETREG_REGISTERED)

		goto err_unlock;

	prog->aux->offload = offload;

	list_add_tail(&offload->offloads, &bpf_prog_offload_devs);

	rtnl_unlock();

	dev_put(offload->netdev);

	up_write(&bpf_devs_lock);



	return 0;

err_unlock:

	up_write(&bpf_devs_lock);

	dev_put(offload->netdev);

err_free:

	kfree(offload);

	return -EINVAL;

}



static int __bpf_offload_ndo(struct bpf_prog *prog, enum bpf_netdev_command cmd,
@@ -126,7 +136,9 @@ void bpf_prog_offload_destroy(struct bpf_prog *prog) 
	wake_up(&offload->verifier_done);



	rtnl_lock();

	down_write(&bpf_devs_lock);

	__bpf_prog_offload_destroy(prog);

	up_write(&bpf_devs_lock);

	rtnl_unlock();



	kfree(offload);
@@ -181,11 +193,13 @@ static int bpf_offload_notification(struct notifier_block *notifier, 
		if (netdev->reg_state != NETREG_UNREGISTERING)

			break;



		down_write(&bpf_devs_lock);

		list_for_each_entry_safe(offload, tmp, &bpf_prog_offload_devs,

					 offloads) {

			if (offload->netdev == netdev)

				__bpf_prog_offload_destroy(offload->prog);

		}

		up_write(&bpf_devs_lock);

		break;

	default:

		break;

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