try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
implement the corresponding function we should call module_put to drop
the refcount.
Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
Signed-off-by: Hangyu Hua <[email protected]>
---
net/sched/cls_api.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 2621550bfddc..92bfb892e638 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
return PTR_ERR(ops);
if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
+ module_put(ops->owner);
return -EOPNOTSUPP;
}
--
2.34.1
On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
> try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
> implement the corresponding function we should call module_put to drop
> the refcount.
Hi Hangyu Hua,
Is this correct even if try_module_get() is
not called via tcf_proto_lookup_ops() ?
> Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
> Signed-off-by: Hangyu Hua <[email protected]>
> ---
> net/sched/cls_api.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 2621550bfddc..92bfb892e638 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
> return PTR_ERR(ops);
> if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
> NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
> + module_put(ops->owner);
> return -EOPNOTSUPP;
> }
>
> --
> 2.34.1
>
>
On 5/6/2023 20:31, Simon Horman wrote:
> On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
>> try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
>> implement the corresponding function we should call module_put to drop
>> the refcount.
>
> Hi Hangyu Hua,
>
> Is this correct even if try_module_get() is
> not called via tcf_proto_lookup_ops() ?
>
tcf_proto_lookup_ops will return error if try_module_get() is not called
in tcf_proto_lookup_ops(). I am not sure what you mean?
Thanks,
Hangyu
>> Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
>> Signed-off-by: Hangyu Hua <[email protected]>
>> ---
>> net/sched/cls_api.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> index 2621550bfddc..92bfb892e638 100644
>> --- a/net/sched/cls_api.c
>> +++ b/net/sched/cls_api.c
>> @@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
>> return PTR_ERR(ops);
>> if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
>> NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
>> + module_put(ops->owner);
>> return -EOPNOTSUPP;
>> }
>>
>> --
>> 2.34.1
>>
>>
On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
> try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
> implement the corresponding function we should call module_put to drop
> the refcount.
>
Code seems reasonable. But commit message is pretty hard to understand.
Please, replace "corresponding" with "required".
Also change the first sentence, do not use "can". From what I see, successful
execution of tcf_proto_lookup_ops always means we now hold reference to module.
CC me in v2, I'll give you Reviewed-by.
> Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
> Signed-off-by: Hangyu Hua <[email protected]>
> ---
> net/sched/cls_api.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 2621550bfddc..92bfb892e638 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
> return PTR_ERR(ops);
> if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
> NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
> + module_put(ops->owner);
> return -EOPNOTSUPP;
> }
>
> --
> 2.34.1
>
>
On Tue, Jun 06, 2023 at 10:13:44AM +0800, Hangyu Hua wrote:
> On 5/6/2023 20:31, Simon Horman wrote:
> > On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
> > > try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
> > > implement the corresponding function we should call module_put to drop
> > > the refcount.
> >
> > Hi Hangyu Hua,
> >
> > Is this correct even if try_module_get() is
> > not called via tcf_proto_lookup_ops() ?
> >
>
> tcf_proto_lookup_ops will return error if try_module_get() is not called in
> tcf_proto_lookup_ops(). I am not sure what you mean?
Thanks,
I think that answers my question.
My concern was if there is a situation where module_put() is
now called, but there was not in fact a reference that should
be released.
...
Mon, Jun 05, 2023 at 09:01:58AM CEST, [email protected] wrote:
>try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
>implement the corresponding function we should call module_put to drop
>the refcount.
Who's "we"? Use imperative mood. Tell the codebase what to do, what to
change, etc.
Code-wise, this is fine. Please fix the patch description.
>
>Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
>Signed-off-by: Hangyu Hua <[email protected]>
>---
> net/sched/cls_api.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>index 2621550bfddc..92bfb892e638 100644
>--- a/net/sched/cls_api.c
>+++ b/net/sched/cls_api.c
>@@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
> return PTR_ERR(ops);
> if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
> NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
>+ module_put(ops->owner);
> return -EOPNOTSUPP;
> }
>
>--
>2.34.1
>
On 6/6/2023 16:53, Larysa Zaremba wrote:
> On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
>> try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
>> implement the corresponding function we should call module_put to drop
>> the refcount.
>>
>
> Code seems reasonable. But commit message is pretty hard to understand.
> Please, replace "corresponding" with "required".
> Also change the first sentence, do not use "can". From what I see, successful
> execution of tcf_proto_lookup_ops always means we now hold reference to module.
>
> CC me in v2, I'll give you Reviewed-by.
>
I apologize for my incorrect English expression. I will send a v2 later.
Thanks,
Hangyu
>> Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
>> Signed-off-by: Hangyu Hua <[email protected]>
>> ---
>> net/sched/cls_api.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> index 2621550bfddc..92bfb892e638 100644
>> --- a/net/sched/cls_api.c
>> +++ b/net/sched/cls_api.c
>> @@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
>> return PTR_ERR(ops);
>> if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
>> NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
>> + module_put(ops->owner);
>> return -EOPNOTSUPP;
>> }
>>
>> --
>> 2.34.1
>>
>>