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

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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: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jakub Kicinski 2017-12-27 18:39:03 -08:00 committed by Daniel Borkmann
parent fb982666e3
commit e0d3974ac7
1 changed files with 24 additions and 10 deletions
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34
kernel/bpf/offload.c
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@ -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;