* [PATCH bpf v3] xdp: Handle device unregister for devmap_hash map type
@ 2019-10-18 19:44 Toke Høiland-Jørgensen
2019-10-18 21:18 ` Martin Lau
0 siblings, 1 reply; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2019-10-18 19:44 UTC (permalink / raw)
To: daniel, ast
Cc: Toke Høiland-Jørgensen, bpf, netdev, kafai, Tetsuo Handa
It seems I forgot to add handling of devmap_hash type maps to the device
unregister hook for devmaps. This omission causes devices to not be
properly released, which causes hangs.
Fix this by adding the missing handler.
Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
v3:
- Use u32 for loop iterator variable
- Since we're holding the lock we can just iterate with hlist_for_each_entry_safe()
v2:
- Grab the update lock while walking the map and removing entries.
kernel/bpf/devmap.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index c0a48f336997..012dbfb0f54b 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -719,6 +719,31 @@ const struct bpf_map_ops dev_map_hash_ops = {
.map_check_btf = map_check_no_btf,
};
+static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
+ struct net_device *netdev)
+{
+ unsigned long flags;
+ u32 i;
+
+ spin_lock_irqsave(&dtab->index_lock, flags);
+ for (i = 0; i < dtab->n_buckets; i++) {
+ struct bpf_dtab_netdev *dev;
+ struct hlist_head *head;
+ struct hlist_node *next;
+
+ head = dev_map_index_hash(dtab, i);
+
+ hlist_for_each_entry_safe(dev, next, head, index_hlist) {
+ if (netdev != dev->dev)
+ continue;
+
+ hlist_del_rcu(&dev->index_hlist);
+ call_rcu(&dev->rcu, __dev_map_entry_free);
+ }
+ }
+ spin_unlock_irqrestore(&dtab->index_lock, flags);
+}
+
static int dev_map_notification(struct notifier_block *notifier,
ulong event, void *ptr)
{
@@ -735,6 +760,11 @@ static int dev_map_notification(struct notifier_block *notifier,
*/
rcu_read_lock();
list_for_each_entry_rcu(dtab, &dev_map_list, list) {
+ if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ dev_map_hash_remove_netdev(dtab, netdev);
+ continue;
+ }
+
for (i = 0; i < dtab->map.max_entries; i++) {
struct bpf_dtab_netdev *dev, *odev;
--
2.23.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf v3] xdp: Handle device unregister for devmap_hash map type
2019-10-18 19:44 [PATCH bpf v3] xdp: Handle device unregister for devmap_hash map type Toke Høiland-Jørgensen
@ 2019-10-18 21:18 ` Martin Lau
2019-10-19 11:16 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 3+ messages in thread
From: Martin Lau @ 2019-10-18 21:18 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: daniel, Alexei Starovoitov, bpf, netdev, Tetsuo Handa
On Fri, Oct 18, 2019 at 09:44:18PM +0200, Toke Høiland-Jørgensen wrote:
> It seems I forgot to add handling of devmap_hash type maps to the device
> unregister hook for devmaps. This omission causes devices to not be
> properly released, which causes hangs.
>
> Fix this by adding the missing handler.
>
> Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index")
> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
> v3:
> - Use u32 for loop iterator variable
> - Since we're holding the lock we can just iterate with hlist_for_each_entry_safe()
> v2:
> - Grab the update lock while walking the map and removing entries.
>
> kernel/bpf/devmap.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index c0a48f336997..012dbfb0f54b 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -719,6 +719,31 @@ const struct bpf_map_ops dev_map_hash_ops = {
> .map_check_btf = map_check_no_btf,
> };
>
> +static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
> + struct net_device *netdev)
> +{
> + unsigned long flags;
> + u32 i;
> +
> + spin_lock_irqsave(&dtab->index_lock, flags);
> + for (i = 0; i < dtab->n_buckets; i++) {
> + struct bpf_dtab_netdev *dev;
> + struct hlist_head *head;
> + struct hlist_node *next;
> +
> + head = dev_map_index_hash(dtab, i);
> +
> + hlist_for_each_entry_safe(dev, next, head, index_hlist) {
> + if (netdev != dev->dev)
> + continue;
> +
> + hlist_del_rcu(&dev->index_hlist);
There is another issue...
"dtab->items--;"
> + call_rcu(&dev->rcu, __dev_map_entry_free);
> + }
> + }
> + spin_unlock_irqrestore(&dtab->index_lock, flags);
> +}
> +
> static int dev_map_notification(struct notifier_block *notifier,
> ulong event, void *ptr)
> {
> @@ -735,6 +760,11 @@ static int dev_map_notification(struct notifier_block *notifier,
> */
> rcu_read_lock();
> list_for_each_entry_rcu(dtab, &dev_map_list, list) {
> + if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
> + dev_map_hash_remove_netdev(dtab, netdev);
> + continue;
> + }
> +
> for (i = 0; i < dtab->map.max_entries; i++) {
> struct bpf_dtab_netdev *dev, *odev;
>
> --
> 2.23.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf v3] xdp: Handle device unregister for devmap_hash map type
2019-10-18 21:18 ` Martin Lau
@ 2019-10-19 11:16 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2019-10-19 11:16 UTC (permalink / raw)
To: Martin Lau; +Cc: daniel, Alexei Starovoitov, bpf, netdev, Tetsuo Handa
Martin Lau <kafai@fb.com> writes:
> On Fri, Oct 18, 2019 at 09:44:18PM +0200, Toke Høiland-Jørgensen wrote:
>> It seems I forgot to add handling of devmap_hash type maps to the device
>> unregister hook for devmaps. This omission causes devices to not be
>> properly released, which causes hangs.
>>
>> Fix this by adding the missing handler.
>>
>> Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index")
>> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>> v3:
>> - Use u32 for loop iterator variable
>> - Since we're holding the lock we can just iterate with hlist_for_each_entry_safe()
>> v2:
>> - Grab the update lock while walking the map and removing entries.
>>
>> kernel/bpf/devmap.c | 30 ++++++++++++++++++++++++++++++
>> 1 file changed, 30 insertions(+)
>>
>> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
>> index c0a48f336997..012dbfb0f54b 100644
>> --- a/kernel/bpf/devmap.c
>> +++ b/kernel/bpf/devmap.c
>> @@ -719,6 +719,31 @@ const struct bpf_map_ops dev_map_hash_ops = {
>> .map_check_btf = map_check_no_btf,
>> };
>>
>> +static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
>> + struct net_device *netdev)
>> +{
>> + unsigned long flags;
>> + u32 i;
>> +
>> + spin_lock_irqsave(&dtab->index_lock, flags);
>> + for (i = 0; i < dtab->n_buckets; i++) {
>> + struct bpf_dtab_netdev *dev;
>> + struct hlist_head *head;
>> + struct hlist_node *next;
>> +
>> + head = dev_map_index_hash(dtab, i);
>> +
>> + hlist_for_each_entry_safe(dev, next, head, index_hlist) {
>> + if (netdev != dev->dev)
>> + continue;
>> +
>> + hlist_del_rcu(&dev->index_hlist);
> There is another issue...
> "dtab->items--;"
Right, of course. Thanks for your diligence in spotting my silly
mistakes! Will send a v4 :)
-Toke
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-10-18 19:44 [PATCH bpf v3] xdp: Handle device unregister for devmap_hash map type Toke Høiland-Jørgensen
2019-10-18 21:18 ` Martin Lau
2019-10-19 11:16 ` Toke Høiland-Jørgensen
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