[PATCH bpf] libbpf: fix race when pinning maps in parallel

[PATCH bpf] libbpf: fix race when pinning maps in parallel

[Martynas Pumputis]

When loading in parallel multiple programs which use the same to-be
pinned map, it is possible that two instances of the loader will call
bpf_object__create_maps() at the same time. If the map doesn't exist
when both instances call bpf_object__reuse_map(), then one of the
instances will fail with EEXIST when calling bpf_map__pin().

Fix the race by retrying creating a map if bpf_map__pin() returns
EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
Fix race condition with map pinning").

Cc: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Martynas Pumputis <m@lambda.lt>
---
 tools/lib/bpf/libbpf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1e04ce724240..7a31c7c3cd21 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
 	char *cp, errmsg[STRERR_BUFSIZE];
 	unsigned int i, j;
 	int err;
+	bool retried = false;
 
 	for (i = 0; i < obj->nr_maps; i++) {
 		map = &obj->maps[i];
 
+retry:
 		if (map->pin_path) {
 			err = bpf_object__reuse_map(map);
 			if (err) {
@@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
 		if (map->pin_path && !map->pinned) {
 			err = bpf_map__pin(map, NULL);
 			if (err) {
+				zclose(map->fd);
+				if (!retried && err == EEXIST) {
+					retried = true;
+					goto retry;
+				}
 				pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
 					map->name, map->pin_path, err);
-				zclose(map->fd);
 				goto err_out;
 			}
 		}
-- 
2.32.0

Re: [PATCH bpf] libbpf: fix race when pinning maps in parallel

[Andrii Nakryiko]

On Mon, Jul 5, 2021 at 12:08 PM Martynas Pumputis <m@lambda.lt> wrote:
>
> When loading in parallel multiple programs which use the same to-be
> pinned map, it is possible that two instances of the loader will call
> bpf_object__create_maps() at the same time. If the map doesn't exist
> when both instances call bpf_object__reuse_map(), then one of the
> instances will fail with EEXIST when calling bpf_map__pin().
>
> Fix the race by retrying creating a map if bpf_map__pin() returns
> EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
> Fix race condition with map pinning").
>
> Cc: Joe Stringer <joe@wand.net.nz>
> Signed-off-by: Martynas Pumputis <m@lambda.lt>
> ---
>  tools/lib/bpf/libbpf.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 1e04ce724240..7a31c7c3cd21 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
>         char *cp, errmsg[STRERR_BUFSIZE];
>         unsigned int i, j;
>         int err;
> +       bool retried = false;

retried has to be reset for each map, so just move it inside the for
loop? you can also generalize it to retry_cnt (> 1 attempts) to allow
for more extreme cases of multiple loaders fighting very heavily

>
>         for (i = 0; i < obj->nr_maps; i++) {
>                 map = &obj->maps[i];
>
> +retry:
>                 if (map->pin_path) {
>                         err = bpf_object__reuse_map(map);
>                         if (err) {
> @@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
>                 if (map->pin_path && !map->pinned) {
>                         err = bpf_map__pin(map, NULL);
>                         if (err) {
> +                               zclose(map->fd);
> +                               if (!retried && err == EEXIST) {

so I'm also wondering... should we commit at this point to trying to
pin and not attempt to re-create the map? I'm worried that
bpf_object__create_map() is not designed and tested to be called
multiple times for the same bpf_map, but it's technically possible for
it to be called multiple times in this scenario. Check the inner map
creation scenario, for example (btw, I think there is a bug in
bpf_object__create_map clean up for inner map, care to take a look at
that as well?).

So unless we want to allow map re-creation if (in a highly unlikely
scenario) someone already unpinned the other instance, I'd say we
should just bpf_map__pin() here directly, maybe in a short loop to
allow for a few attempts.

> +                                       retried = true;
> +                                       goto retry;
> +                               }
>                                 pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
>                                         map->name, map->pin_path, err);
> -                               zclose(map->fd);
>                                 goto err_out;
>                         }
>                 }
> --
> 2.32.0
>

Re: [PATCH bpf] libbpf: fix race when pinning maps in parallel

[Martynas Pumputis]

On 7/8/21 12:38 AM, Andrii Nakryiko wrote:
> On Mon, Jul 5, 2021 at 12:08 PM Martynas Pumputis <m@lambda.lt> wrote:
>>
>> When loading in parallel multiple programs which use the same to-be
>> pinned map, it is possible that two instances of the loader will call
>> bpf_object__create_maps() at the same time. If the map doesn't exist
>> when both instances call bpf_object__reuse_map(), then one of the
>> instances will fail with EEXIST when calling bpf_map__pin().
>>
>> Fix the race by retrying creating a map if bpf_map__pin() returns
>> EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
>> Fix race condition with map pinning").
>>
>> Cc: Joe Stringer <joe@wand.net.nz>
>> Signed-off-by: Martynas Pumputis <m@lambda.lt>
>> ---
>>   tools/lib/bpf/libbpf.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index 1e04ce724240..7a31c7c3cd21 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
>>          char *cp, errmsg[STRERR_BUFSIZE];
>>          unsigned int i, j;
>>          int err;
>> +       bool retried = false;
> 
> retried has to be reset for each map, so just move it inside the for
> loop? you can also generalize it to retry_cnt (> 1 attempts) to allow
> for more extreme cases of multiple loaders fighting very heavily

If we move "retried = false" to inside the loop, then there is no need 
for retry_cnt. Single retry for each map should be enough to resolve the 
race. In any case, I'm going to move "retried = false", as you suggested.

> 
>>
>>          for (i = 0; i < obj->nr_maps; i++) {
>>                  map = &obj->maps[i];
>>
>> +retry:
>>                  if (map->pin_path) {
>>                          err = bpf_object__reuse_map(map);
>>                          if (err) {
>> @@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
>>                  if (map->pin_path && !map->pinned) {
>>                          err = bpf_map__pin(map, NULL);
>>                          if (err) {
>> +                               zclose(map->fd);
>> +                               if (!retried && err == EEXIST) {
> 
> so I'm also wondering... should we commit at this point to trying to
> pin and not attempt to re-create the map? I'm worried that
> bpf_object__create_map() is not designed and tested to be called
> multiple times for the same bpf_map, but it's technically possible for
> it to be called multiple times in this scenario. Check the inner map

Good call. I'm going to add "if (retried && map->fd < 0) { return 
-ENOENT; }" after the "if (map->pinned) { err = bpf_object__reuse_map() 
... }" statement. This should prevent from invoking 
bpf_object__create_map() multiple times.

> creation scenario, for example (btw, I think there is a bug in
> bpf_object__create_map clean up for inner map, care to take a look at
> that as well?).

In the case of the inner map, it should be destroyed inside 
bpf_object__create_map() after a successful BPF_MAP_CREATE. So AFAIU, 
there should be no need for the cleanup. Or do I miss something?

> 
> So unless we want to allow map re-creation if (in a highly unlikely
> scenario) someone already unpinned the other instance, I'd say we
> should just bpf_map__pin() here directly, maybe in a short loop to
> allow for a few attempts.
> 
>> +                                       retried = true;
>> +                                       goto retry;
>> +                               }
>>                                  pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
>>                                          map->name, map->pin_path, err);
>> -                               zclose(map->fd);
>>                                  goto err_out;
>>                          }
>>                  }
>> --
>> 2.32.0
>>

Re: [PATCH bpf] libbpf: fix race when pinning maps in parallel

[Andrii Nakryiko]

On Thu, Jul 8, 2021 at 8:50 AM Martynas Pumputis <m@lambda.lt> wrote:
>
>
>
> On 7/8/21 12:38 AM, Andrii Nakryiko wrote:
> > On Mon, Jul 5, 2021 at 12:08 PM Martynas Pumputis <m@lambda.lt> wrote:
> >>
> >> When loading in parallel multiple programs which use the same to-be
> >> pinned map, it is possible that two instances of the loader will call
> >> bpf_object__create_maps() at the same time. If the map doesn't exist
> >> when both instances call bpf_object__reuse_map(), then one of the
> >> instances will fail with EEXIST when calling bpf_map__pin().
> >>
> >> Fix the race by retrying creating a map if bpf_map__pin() returns
> >> EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
> >> Fix race condition with map pinning").
> >>
> >> Cc: Joe Stringer <joe@wand.net.nz>
> >> Signed-off-by: Martynas Pumputis <m@lambda.lt>
> >> ---
> >>   tools/lib/bpf/libbpf.c | 8 +++++++-
> >>   1 file changed, 7 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> >> index 1e04ce724240..7a31c7c3cd21 100644
> >> --- a/tools/lib/bpf/libbpf.c
> >> +++ b/tools/lib/bpf/libbpf.c
> >> @@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
> >>          char *cp, errmsg[STRERR_BUFSIZE];
> >>          unsigned int i, j;
> >>          int err;
> >> +       bool retried = false;
> >
> > retried has to be reset for each map, so just move it inside the for
> > loop? you can also generalize it to retry_cnt (> 1 attempts) to allow
> > for more extreme cases of multiple loaders fighting very heavily
>
> If we move "retried = false" to inside the loop, then there is no need
> for retry_cnt. Single retry for each map should be enough to resolve the
> race. In any case, I'm going to move "retried = false", as you suggested.

Right, I was originally thinking about the case where already pinned
map might get unpinned. But then subsequently rejected the idea of
re-creating the map :) So single retry should do.

>
> >
> >>
> >>          for (i = 0; i < obj->nr_maps; i++) {
> >>                  map = &obj->maps[i];
> >>
> >> +retry:
> >>                  if (map->pin_path) {
> >>                          err = bpf_object__reuse_map(map);
> >>                          if (err) {
> >> @@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
> >>                  if (map->pin_path && !map->pinned) {
> >>                          err = bpf_map__pin(map, NULL);
> >>                          if (err) {
> >> +                               zclose(map->fd);
> >> +                               if (!retried && err == EEXIST) {
> >
> > so I'm also wondering... should we commit at this point to trying to
> > pin and not attempt to re-create the map? I'm worried that
> > bpf_object__create_map() is not designed and tested to be called
> > multiple times for the same bpf_map, but it's technically possible for
> > it to be called multiple times in this scenario. Check the inner map
>
> Good call. I'm going to add "if (retried && map->fd < 0) { return
> -ENOENT; }" after the "if (map->pinned) { err = bpf_object__reuse_map()
> ... }" statement. This should prevent from invoking
> bpf_object__create_map() multiple times.
>
> > creation scenario, for example (btw, I think there is a bug in
> > bpf_object__create_map clean up for inner map, care to take a look at
> > that as well?).
>
> In the case of the inner map, it should be destroyed inside
> bpf_object__create_map() after a successful BPF_MAP_CREATE. So AFAIU,
> there should be no need for the cleanup. Or do I miss something?

But if outer map creation fails, we won't do
bpf_map__destroy(map->inner_map);, which is one bug. And then with
your retry logic we also don't clean up the internal state of the
bpf_map, which is another one. It would be good to add a self-test
simulating such situations (e.g., by specifying wrong key_size for
outer_map, but correct inner_map definition). Not sure how to reliably
simulate this pinning race, though.

Can you please add at least the first test case?

>
> >
> > So unless we want to allow map re-creation if (in a highly unlikely
> > scenario) someone already unpinned the other instance, I'd say we
> > should just bpf_map__pin() here directly, maybe in a short loop to
> > allow for a few attempts.
> >
> >> +                                       retried = true;
> >> +                                       goto retry;
> >> +                               }
> >>                                  pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
> >>                                          map->name, map->pin_path, err);
> >> -                               zclose(map->fd);
> >>                                  goto err_out;
> >>                          }
> >>                  }
> >> --
> >> 2.32.0
> >>

Re: [PATCH bpf] libbpf: fix race when pinning maps in parallel

[Martynas Pumputis]

On 7/8/21 10:33 PM, Andrii Nakryiko wrote:
> On Thu, Jul 8, 2021 at 8:50 AM Martynas Pumputis <m@lambda.lt> wrote:
>>
>>
>>
>> On 7/8/21 12:38 AM, Andrii Nakryiko wrote:
>>> On Mon, Jul 5, 2021 at 12:08 PM Martynas Pumputis <m@lambda.lt> wrote:
>>>>
>>>> When loading in parallel multiple programs which use the same to-be
>>>> pinned map, it is possible that two instances of the loader will call
>>>> bpf_object__create_maps() at the same time. If the map doesn't exist
>>>> when both instances call bpf_object__reuse_map(), then one of the
>>>> instances will fail with EEXIST when calling bpf_map__pin().
>>>>
>>>> Fix the race by retrying creating a map if bpf_map__pin() returns
>>>> EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
>>>> Fix race condition with map pinning").
>>>>
>>>> Cc: Joe Stringer <joe@wand.net.nz>
>>>> Signed-off-by: Martynas Pumputis <m@lambda.lt>
>>>> ---
>>>>    tools/lib/bpf/libbpf.c | 8 +++++++-
>>>>    1 file changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>>>> index 1e04ce724240..7a31c7c3cd21 100644
>>>> --- a/tools/lib/bpf/libbpf.c
>>>> +++ b/tools/lib/bpf/libbpf.c
>>>> @@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
>>>>           char *cp, errmsg[STRERR_BUFSIZE];
>>>>           unsigned int i, j;
>>>>           int err;
>>>> +       bool retried = false;
>>>
>>> retried has to be reset for each map, so just move it inside the for
>>> loop? you can also generalize it to retry_cnt (> 1 attempts) to allow
>>> for more extreme cases of multiple loaders fighting very heavily
>>
>> If we move "retried = false" to inside the loop, then there is no need
>> for retry_cnt. Single retry for each map should be enough to resolve the
>> race. In any case, I'm going to move "retried = false", as you suggested.
> 
> Right, I was originally thinking about the case where already pinned
> map might get unpinned. But then subsequently rejected the idea of
> re-creating the map :) So single retry should do.
> 
>>
>>>
>>>>
>>>>           for (i = 0; i < obj->nr_maps; i++) {
>>>>                   map = &obj->maps[i];
>>>>
>>>> +retry:
>>>>                   if (map->pin_path) {
>>>>                           err = bpf_object__reuse_map(map);
>>>>                           if (err) {
>>>> @@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
>>>>                   if (map->pin_path && !map->pinned) {
>>>>                           err = bpf_map__pin(map, NULL);
>>>>                           if (err) {
>>>> +                               zclose(map->fd);
>>>> +                               if (!retried && err == EEXIST) {
>>>
>>> so I'm also wondering... should we commit at this point to trying to
>>> pin and not attempt to re-create the map? I'm worried that
>>> bpf_object__create_map() is not designed and tested to be called
>>> multiple times for the same bpf_map, but it's technically possible for
>>> it to be called multiple times in this scenario. Check the inner map
>>
>> Good call. I'm going to add "if (retried && map->fd < 0) { return
>> -ENOENT; }" after the "if (map->pinned) { err = bpf_object__reuse_map()
>> ... }" statement. This should prevent from invoking
>> bpf_object__create_map() multiple times.
>>
>>> creation scenario, for example (btw, I think there is a bug in
>>> bpf_object__create_map clean up for inner map, care to take a look at
>>> that as well?).
>>
>> In the case of the inner map, it should be destroyed inside
>> bpf_object__create_map() after a successful BPF_MAP_CREATE. So AFAIU,
>> there should be no need for the cleanup. Or do I miss something?
> 
> But if outer map creation fails, we won't do
> bpf_map__destroy(map->inner_map);, which is one bug. And then with
> your retry logic we also don't clean up the internal state of the
> bpf_map, which is another one. It would be good to add a self-test
> simulating such situations (e.g., by specifying wrong key_size for
> outer_map, but correct inner_map definition). Not sure how to reliably
> simulate this pinning race, though.
> 
> Can you please add at least the first test case?

Yep, I've sent the patch with a test case for the first bug. Thanks for 
explaining.

Anyway, regarding the proposed retry, I think the safest approach is to 
bail before invoking bpf_object__create_map() for the second time (when 
we retry). This would avoid any issues with idempotence of 
bpf_object__create_map() and should solve most of the cases (except when 
a map gets unpinned before the retry, but I expect this to be a very 
unusual and rare situation).

> 
>>
>>>
>>> So unless we want to allow map re-creation if (in a highly unlikely
>>> scenario) someone already unpinned the other instance, I'd say we
>>> should just bpf_map__pin() here directly, maybe in a short loop to
>>> allow for a few attempts.
>>>
>>>> +                                       retried = true;
>>>> +                                       goto retry;
>>>> +                               }
>>>>                                   pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
>>>>                                           map->name, map->pin_path, err);
>>>> -                               zclose(map->fd);
>>>>                                   goto err_out;
>>>>                           }
>>>>                   }
>>>> --
>>>> 2.32.0
>>>>

Re: [PATCH bpf] libbpf: fix race when pinning maps in parallel

[Martynas Pumputis]

On 7/8/21 10:33 PM, Andrii Nakryiko wrote:
> On Thu, Jul 8, 2021 at 8:50 AM Martynas Pumputis <m@lambda.lt> wrote:
>>
>>
>>
>> On 7/8/21 12:38 AM, Andrii Nakryiko wrote:
>>> On Mon, Jul 5, 2021 at 12:08 PM Martynas Pumputis <m@lambda.lt> wrote:
>>>>
>>>> When loading in parallel multiple programs which use the same to-be
>>>> pinned map, it is possible that two instances of the loader will call
>>>> bpf_object__create_maps() at the same time. If the map doesn't exist
>>>> when both instances call bpf_object__reuse_map(), then one of the
>>>> instances will fail with EEXIST when calling bpf_map__pin().
>>>>
>>>> Fix the race by retrying creating a map if bpf_map__pin() returns
>>>> EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
>>>> Fix race condition with map pinning").
>>>>
>>>> Cc: Joe Stringer <joe@wand.net.nz>
>>>> Signed-off-by: Martynas Pumputis <m@lambda.lt>
>>>> ---
>>>>    tools/lib/bpf/libbpf.c | 8 +++++++-
>>>>    1 file changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>>>> index 1e04ce724240..7a31c7c3cd21 100644
>>>> --- a/tools/lib/bpf/libbpf.c
>>>> +++ b/tools/lib/bpf/libbpf.c
>>>> @@ -4616,10 +4616,12 @@ bpf_object__create_maps(struct bpf_object *obj)
>>>>           char *cp, errmsg[STRERR_BUFSIZE];
>>>>           unsigned int i, j;
>>>>           int err;
>>>> +       bool retried = false;
>>>
>>> retried has to be reset for each map, so just move it inside the for
>>> loop? you can also generalize it to retry_cnt (> 1 attempts) to allow
>>> for more extreme cases of multiple loaders fighting very heavily
>>
>> If we move "retried = false" to inside the loop, then there is no need
>> for retry_cnt. Single retry for each map should be enough to resolve the
>> race. In any case, I'm going to move "retried = false", as you suggested.
> 
> Right, I was originally thinking about the case where already pinned
> map might get unpinned. But then subsequently rejected the idea of
> re-creating the map :) So single retry should do.
> 
>>
>>>
>>>>
>>>>           for (i = 0; i < obj->nr_maps; i++) {
>>>>                   map = &obj->maps[i];
>>>>
>>>> +retry:
>>>>                   if (map->pin_path) {
>>>>                           err = bpf_object__reuse_map(map);
>>>>                           if (err) {
>>>> @@ -4660,9 +4662,13 @@ bpf_object__create_maps(struct bpf_object *obj)
>>>>                   if (map->pin_path && !map->pinned) {
>>>>                           err = bpf_map__pin(map, NULL);
>>>>                           if (err) {
>>>> +                               zclose(map->fd);
>>>> +                               if (!retried && err == EEXIST) {
>>>
>>> so I'm also wondering... should we commit at this point to trying to
>>> pin and not attempt to re-create the map? I'm worried that
>>> bpf_object__create_map() is not designed and tested to be called
>>> multiple times for the same bpf_map, but it's technically possible for
>>> it to be called multiple times in this scenario. Check the inner map
>>
>> Good call. I'm going to add "if (retried && map->fd < 0) { return
>> -ENOENT; }" after the "if (map->pinned) { err = bpf_object__reuse_map()
>> ... }" statement. This should prevent from invoking
>> bpf_object__create_map() multiple times.
>>
>>> creation scenario, for example (btw, I think there is a bug in
>>> bpf_object__create_map clean up for inner map, care to take a look at
>>> that as well?).
>>
>> In the case of the inner map, it should be destroyed inside
>> bpf_object__create_map() after a successful BPF_MAP_CREATE. So AFAIU,
>> there should be no need for the cleanup. Or do I miss something?
> 
> But if outer map creation fails, we won't do
> bpf_map__destroy(map->inner_map);, which is one bug. And then with
> your retry logic we also don't clean up the internal state of the
> bpf_map, which is another one. It would be good to add a self-test
> simulating such situations (e.g., by specifying wrong key_size for
> outer_map, but correct inner_map definition). Not sure how to reliably
> simulate this pinning race, though.

Regarding the second case (i.e., not cleaning up the internal state), I 
think no additional cleanup is needed with this patch [1] (main diff 
from prev vsn is that we call bpf_object__map_create() only once).

The relevant calls are the following:

- bpf_object__create_map(): map->inner_map is destroyed anyway after a 
successful call, map->fd is closed if pinning fails.
- bpf_object__populate_internal_map(): created map elements will be 
destroyed upon close(map->fd).
- init_map_slots(): slots are freed after their initialization.

[1]: https://gist.github.com/brb/fff66e47586373fdc1fe39b88175036c

> 
> Can you please add at least the first test case?
> 
>>
>>>
>>> So unless we want to allow map re-creation if (in a highly unlikely
>>> scenario) someone already unpinned the other instance, I'd say we
>>> should just bpf_map__pin() here directly, maybe in a short loop to
>>> allow for a few attempts.
>>>
>>>> +                                       retried = true;
>>>> +                                       goto retry;
>>>> +                               }
>>>>                                   pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
>>>>                                           map->name, map->pin_path, err);
>>>> -                               zclose(map->fd);
>>>>                                   goto err_out;
>>>>                           }
>>>>                   }
>>>> --
>>>> 2.32.0
>>>>