* [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference()
@ 2021-06-28 23:00 Toke Høiland-Jørgensen
2021-06-28 23:05 ` Paul E. McKenney
2021-06-28 23:55 ` Martin KaFai Lau
0 siblings, 2 replies; 4+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-06-28 23:00 UTC (permalink / raw)
To: bpf, netdev
Cc: Martin KaFai Lau, Hangbin Liu, Jesper Dangaard Brouer,
Magnus Karlsson, Paul E . McKenney, Jakub Kicinski,
Toke Høiland-Jørgensen, kernel test robot
There were a couple of READ_ONCE()-invocations left-over by the devmap RCU
conversion. Convert these to rcu_dereference() as well to avoid complaints
from sparse.
Fixes: 782347b6bcad ("xdp: Add proper __rcu annotations to redirect map entries")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
kernel/bpf/devmap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 2f6bd75cd682..7a0c008f751b 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -558,7 +558,7 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
for (i = 0; i < map->max_entries; i++) {
- dst = READ_ONCE(dtab->netdev_map[i]);
+ dst = rcu_dereference(dtab->netdev_map[i]);
if (!is_valid_dst(dst, xdp, exclude_ifindex))
continue;
@@ -654,7 +654,7 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
for (i = 0; i < map->max_entries; i++) {
- dst = READ_ONCE(dtab->netdev_map[i]);
+ dst = rcu_dereference(dtab->netdev_map[i]);
if (!dst || dst->dev->ifindex == exclude_ifindex)
continue;
--
2.32.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference()
2021-06-28 23:00 [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference() Toke Høiland-Jørgensen
@ 2021-06-28 23:05 ` Paul E. McKenney
2021-06-28 23:55 ` Martin KaFai Lau
1 sibling, 0 replies; 4+ messages in thread
From: Paul E. McKenney @ 2021-06-28 23:05 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: bpf, netdev, Martin KaFai Lau, Hangbin Liu,
Jesper Dangaard Brouer, Magnus Karlsson, Jakub Kicinski,
kernel test robot
On Tue, Jun 29, 2021 at 01:00:51AM +0200, Toke Høiland-Jørgensen wrote:
> There were a couple of READ_ONCE()-invocations left-over by the devmap RCU
> conversion. Convert these to rcu_dereference() as well to avoid complaints
> from sparse.
>
> Fixes: 782347b6bcad ("xdp: Add proper __rcu annotations to redirect map entries")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> kernel/bpf/devmap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index 2f6bd75cd682..7a0c008f751b 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -558,7 +558,7 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
>
> if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
> for (i = 0; i < map->max_entries; i++) {
> - dst = READ_ONCE(dtab->netdev_map[i]);
> + dst = rcu_dereference(dtab->netdev_map[i]);
> if (!is_valid_dst(dst, xdp, exclude_ifindex))
> continue;
>
> @@ -654,7 +654,7 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
>
> if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
> for (i = 0; i < map->max_entries; i++) {
> - dst = READ_ONCE(dtab->netdev_map[i]);
> + dst = rcu_dereference(dtab->netdev_map[i]);
> if (!dst || dst->dev->ifindex == exclude_ifindex)
> continue;
>
> --
> 2.32.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference()
2021-06-28 23:00 [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference() Toke Høiland-Jørgensen
2021-06-28 23:05 ` Paul E. McKenney
@ 2021-06-28 23:55 ` Martin KaFai Lau
2021-06-29 9:37 ` Toke Høiland-Jørgensen
1 sibling, 1 reply; 4+ messages in thread
From: Martin KaFai Lau @ 2021-06-28 23:55 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: bpf, netdev, Hangbin Liu, Jesper Dangaard Brouer,
Magnus Karlsson, Paul E . McKenney, Jakub Kicinski,
kernel test robot
On Tue, Jun 29, 2021 at 01:00:51AM +0200, Toke Høiland-Jørgensen wrote:
> There were a couple of READ_ONCE()-invocations left-over by the devmap RCU
> conversion. Convert these to rcu_dereference() as well to avoid complaints
> from sparse.
>
> Fixes: 782347b6bcad ("xdp: Add proper __rcu annotations to redirect map entries")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
> kernel/bpf/devmap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index 2f6bd75cd682..7a0c008f751b 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -558,7 +558,7 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
>
> if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
> for (i = 0; i < map->max_entries; i++) {
> - dst = READ_ONCE(dtab->netdev_map[i]);
> + dst = rcu_dereference(dtab->netdev_map[i]);
__dev_map_lookup_elem() uses rcu_dereference_check(dtab->netdev_map[key], rcu_read_lock_bh_held()).
It is not needed here?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference()
2021-06-28 23:55 ` Martin KaFai Lau
@ 2021-06-29 9:37 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 4+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-06-29 9:37 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: bpf, netdev, Hangbin Liu, Jesper Dangaard Brouer,
Magnus Karlsson, Paul E . McKenney, Jakub Kicinski,
kernel test robot
Martin KaFai Lau <kafai@fb.com> writes:
> On Tue, Jun 29, 2021 at 01:00:51AM +0200, Toke Høiland-Jørgensen wrote:
>> There were a couple of READ_ONCE()-invocations left-over by the devmap RCU
>> conversion. Convert these to rcu_dereference() as well to avoid complaints
>> from sparse.
>>
>> Fixes: 782347b6bcad ("xdp: Add proper __rcu annotations to redirect map entries")
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>> kernel/bpf/devmap.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
>> index 2f6bd75cd682..7a0c008f751b 100644
>> --- a/kernel/bpf/devmap.c
>> +++ b/kernel/bpf/devmap.c
>> @@ -558,7 +558,7 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
>>
>> if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
>> for (i = 0; i < map->max_entries; i++) {
>> - dst = READ_ONCE(dtab->netdev_map[i]);
>> + dst = rcu_dereference(dtab->netdev_map[i]);
> __dev_map_lookup_elem() uses rcu_dereference_check(dtab->netdev_map[key], rcu_read_lock_bh_held()).
> It is not needed here?
Hmm, I somehow managed to convince myself last night that it wasn't, but
looking at it again now I think you're right. Will send a v2.
-Toke
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-06-28 23:00 [PATCH bpf-next] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference() Toke Høiland-Jørgensen
2021-06-28 23:05 ` Paul E. McKenney
2021-06-28 23:55 ` Martin KaFai Lau
2021-06-29 9:37 ` Toke Høiland-Jørgensen
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