* [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type
@ 2019-10-17 10:52 Toke Høiland-Jørgensen
2019-10-17 19:02 ` Martin Lau
0 siblings, 1 reply; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2019-10-17 10:52 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>
---
v2:
- Grab the update lock while walking the map and removing entries.
kernel/bpf/devmap.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index d27f3b60ff6d..a0a1153da5ae 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -719,6 +719,38 @@ 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;
+ int i;
+
+ spin_lock_irqsave(&dtab->index_lock, flags);
+ for (i = 0; i < dtab->n_buckets; i++) {
+ struct bpf_dtab_netdev *dev, *odev;
+ struct hlist_head *head;
+
+ head = dev_map_index_hash(dtab, i);
+ dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
+ struct bpf_dtab_netdev,
+ index_hlist);
+
+ while (dev) {
+ odev = (netdev == dev->dev) ? dev : NULL;
+ dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
+ struct bpf_dtab_netdev,
+ index_hlist);
+
+ if (odev) {
+ hlist_del_rcu(&odev->index_hlist);
+ call_rcu(&odev->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 +767,11 @@ 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] 5+ messages in thread
* Re: [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type
2019-10-17 10:52 [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type Toke Høiland-Jørgensen
@ 2019-10-17 19:02 ` Martin Lau
2019-10-18 10:26 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 5+ messages in thread
From: Martin Lau @ 2019-10-17 19:02 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: daniel, Alexei Starovoitov, bpf, netdev, Tetsuo Handa
On Thu, Oct 17, 2019 at 12:52:32PM +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>
> ---
> v2:
> - Grab the update lock while walking the map and removing entries.
>
> kernel/bpf/devmap.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index d27f3b60ff6d..a0a1153da5ae 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -719,6 +719,38 @@ 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;
> + int i;
dtab->n_buckets is u32.
> +
> + spin_lock_irqsave(&dtab->index_lock, flags);
> + for (i = 0; i < dtab->n_buckets; i++) {
> + struct bpf_dtab_netdev *dev, *odev;
> + struct hlist_head *head;
> +
> + head = dev_map_index_hash(dtab, i);
> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
The spinlock has already been held. Is rcu_deref still needed?
> + struct bpf_dtab_netdev,
> + index_hlist);
> +
> + while (dev) {
> + odev = (netdev == dev->dev) ? dev : NULL;
> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
> + struct bpf_dtab_netdev,
> + index_hlist);
> +
> + if (odev) {
> + hlist_del_rcu(&odev->index_hlist);
> + call_rcu(&odev->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 +767,11 @@ 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] 5+ messages in thread
* Re: [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type
2019-10-17 19:02 ` Martin Lau
@ 2019-10-18 10:26 ` Toke Høiland-Jørgensen
2019-10-18 16:50 ` Martin Lau
0 siblings, 1 reply; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2019-10-18 10:26 UTC (permalink / raw)
To: Martin Lau; +Cc: daniel, Alexei Starovoitov, bpf, netdev, Tetsuo Handa
Martin Lau <kafai@fb.com> writes:
> On Thu, Oct 17, 2019 at 12:52:32PM +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>
>> ---
>> v2:
>> - Grab the update lock while walking the map and removing entries.
>>
>> kernel/bpf/devmap.c | 37 +++++++++++++++++++++++++++++++++++++
>> 1 file changed, 37 insertions(+)
>>
>> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
>> index d27f3b60ff6d..a0a1153da5ae 100644
>> --- a/kernel/bpf/devmap.c
>> +++ b/kernel/bpf/devmap.c
>> @@ -719,6 +719,38 @@ 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;
>> + int i;
> dtab->n_buckets is u32.
Oh, right, will fix.
>> +
>> + spin_lock_irqsave(&dtab->index_lock, flags);
>> + for (i = 0; i < dtab->n_buckets; i++) {
>> + struct bpf_dtab_netdev *dev, *odev;
>> + struct hlist_head *head;
>> +
>> + head = dev_map_index_hash(dtab, i);
>> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
> The spinlock has already been held. Is rcu_deref still needed?
I guess it's not strictly needed, but since it's an rcu-protected list,
and hlist_first_rcu() returns an __rcu-annotated type, I think we will
get a 'sparse' warning if it's omitted, no?
And since it's just a READ_ONCE, it doesn't actually hurt since this is
not the fast path, so I'd lean towards just keeping it? WDYT?
-Toke
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type
2019-10-18 10:26 ` Toke Høiland-Jørgensen
@ 2019-10-18 16:50 ` Martin Lau
2019-10-18 19:28 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 5+ messages in thread
From: Martin Lau @ 2019-10-18 16:50 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: daniel, Alexei Starovoitov, bpf, netdev, Tetsuo Handa
On Fri, Oct 18, 2019 at 12:26:55PM +0200, Toke Høiland-Jørgensen wrote:
> Martin Lau <kafai@fb.com> writes:
>
> > On Thu, Oct 17, 2019 at 12:52:32PM +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>
> >> ---
> >> v2:
> >> - Grab the update lock while walking the map and removing entries.
> >>
> >> kernel/bpf/devmap.c | 37 +++++++++++++++++++++++++++++++++++++
> >> 1 file changed, 37 insertions(+)
> >>
> >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> >> index d27f3b60ff6d..a0a1153da5ae 100644
> >> --- a/kernel/bpf/devmap.c
> >> +++ b/kernel/bpf/devmap.c
> >> @@ -719,6 +719,38 @@ 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;
> >> + int i;
> > dtab->n_buckets is u32.
>
> Oh, right, will fix.
>
> >> +
> >> + spin_lock_irqsave(&dtab->index_lock, flags);
> >> + for (i = 0; i < dtab->n_buckets; i++) {
> >> + struct bpf_dtab_netdev *dev, *odev;
> >> + struct hlist_head *head;
> >> +
> >> + head = dev_map_index_hash(dtab, i);
> >> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
> > The spinlock has already been held. Is rcu_deref still needed?
>
> I guess it's not strictly needed, but since it's an rcu-protected list,
> and hlist_first_rcu() returns an __rcu-annotated type, I think we will
> get a 'sparse' warning if it's omitted, no?
>
> And since it's just a READ_ONCE, it doesn't actually hurt since this is
> not the fast path, so I'd lean towards just keeping it? WDYT?
>
Can hlist_for_each_safe() be used instead then?
A bonus is the following long line will go away.
I think the change will be simpler also.
> + struct bpf_dtab_netdev,
> + index_hlist);
> +
> + while (dev) {
> + odev = (netdev == dev->dev) ? dev : NULL;
> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
> + struct bpf_dtab_netdev,
> + index_hlist);
> +
> + if (odev) {
> + hlist_del_rcu(&odev->index_hlist);
> + call_rcu(&odev->rcu,
> + __dev_map_entry_free);
> + }
> + }
> + }
> + spin_unlock_irqrestore(&dtab->index_lock, flags);
> +}
> +
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type
2019-10-18 16:50 ` Martin Lau
@ 2019-10-18 19:28 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2019-10-18 19:28 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 12:26:55PM +0200, Toke Høiland-Jørgensen wrote:
>> Martin Lau <kafai@fb.com> writes:
>>
>> > On Thu, Oct 17, 2019 at 12:52:32PM +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>
>> >> ---
>> >> v2:
>> >> - Grab the update lock while walking the map and removing entries.
>> >>
>> >> kernel/bpf/devmap.c | 37 +++++++++++++++++++++++++++++++++++++
>> >> 1 file changed, 37 insertions(+)
>> >>
>> >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
>> >> index d27f3b60ff6d..a0a1153da5ae 100644
>> >> --- a/kernel/bpf/devmap.c
>> >> +++ b/kernel/bpf/devmap.c
>> >> @@ -719,6 +719,38 @@ 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;
>> >> + int i;
>> > dtab->n_buckets is u32.
>>
>> Oh, right, will fix.
>>
>> >> +
>> >> + spin_lock_irqsave(&dtab->index_lock, flags);
>> >> + for (i = 0; i < dtab->n_buckets; i++) {
>> >> + struct bpf_dtab_netdev *dev, *odev;
>> >> + struct hlist_head *head;
>> >> +
>> >> + head = dev_map_index_hash(dtab, i);
>> >> + dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
>> > The spinlock has already been held. Is rcu_deref still needed?
>>
>> I guess it's not strictly needed, but since it's an rcu-protected list,
>> and hlist_first_rcu() returns an __rcu-annotated type, I think we will
>> get a 'sparse' warning if it's omitted, no?
>>
>> And since it's just a READ_ONCE, it doesn't actually hurt since this is
>> not the fast path, so I'd lean towards just keeping it? WDYT?
>>
> Can hlist_for_each_safe() be used instead then?
> A bonus is the following long line will go away.
> I think the change will be simpler also.
Ohhh, yes it can! I was looking for that variant of the for_each macro
(the removal-safe one) and scratching my head as to why it wasn't there.
Dunno how I missed that; thanks, will fix and resend! :)
-Toke
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-10-18 19:28 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-17 10:52 [PATCH bpf v2] xdp: Handle device unregister for devmap_hash map type Toke Høiland-Jørgensen
2019-10-17 19:02 ` Martin Lau
2019-10-18 10:26 ` Toke Høiland-Jørgensen
2019-10-18 16:50 ` Martin Lau
2019-10-18 19:28 ` Toke Høiland-Jørgensen
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).