* Attempt to auto-load em_cmp.ko results in negative module refcnt @ 2015-02-16 10:59 Ignacy Gawedzki 2015-02-16 15:03 ` Ignacy Gawedzki 0 siblings, 1 reply; 9+ messages in thread From: Ignacy Gawedzki @ 2015-02-16 10:59 UTC (permalink / raw) To: netdev Hi, This simple test case tc qdisc add dev eth0 root handle 1: htb tc class add dev eth0 root classid 1: htb rate 1Gbit tc class add dev eth0 parent 1: classid 1:1 htb rate 1Gbit tc filter add dev eth0 parent 1: basic match 'cmp(u8 at 0 eq 0)' classid 1:1 fails with the following RTNETLINK answers: No such file or directory We have an error talking to the kernel if em_cmp.ko is not loaded beforehand. After that, lsmod shows that em_cmp.ko is loaded indeed, but its usage count is -1 and an attempd to unload the module results in a "BUG at kernel/module.c:752". This has been broken pretty recently, I'm currently attempting a git bisect on this. -- Ignacy Gawędzki R&D Engineer Green Communications ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Attempt to auto-load em_cmp.ko results in negative module refcnt 2015-02-16 10:59 Attempt to auto-load em_cmp.ko results in negative module refcnt Ignacy Gawedzki @ 2015-02-16 15:03 ` Ignacy Gawedzki 2015-02-16 18:13 ` [PATCH net] ematch: Fix auto-loading of ematch modules Ignacy Gawędzki 0 siblings, 1 reply; 9+ messages in thread From: Ignacy Gawedzki @ 2015-02-16 15:03 UTC (permalink / raw) To: netdev On Mon, Feb 16, 2015 at 11:59:12AM +0100, thus spake Ignacy Gawedzki: > This has been broken pretty recently, I'm currently attempting a git bisect on > this. Okay, the bisect tells this appeared with e513cc1c07e2ab93a4514eec9833e031df3e30bb, FWIW. -- Ignacy Gawędzki R&D Engineer Green Communications ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH net] ematch: Fix auto-loading of ematch modules. 2015-02-16 15:03 ` Ignacy Gawedzki @ 2015-02-16 18:13 ` Ignacy Gawędzki 2015-02-16 18:36 ` Cong Wang 0 siblings, 1 reply; 9+ messages in thread From: Ignacy Gawędzki @ 2015-02-16 18:13 UTC (permalink / raw) To: netdev In tcf_em_validate(), when calling tcf_em_lookup(), don't put the resulting pointer directly into em->ops, if the function is to possibly return -EAGAIN after module auto-loading. Otherwise, module_put() will be called by tcf_em_tree_destroy() on em->ops->owner, while it has already been called by tcf_em_validate() before return. Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> --- net/sched/ematch.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/sched/ematch.c b/net/sched/ematch.c index 6742200..39fbe2f 100644 --- a/net/sched/ematch.c +++ b/net/sched/ematch.c @@ -176,6 +176,7 @@ static int tcf_em_validate(struct tcf_proto *tp, { int err = -EINVAL; struct tcf_ematch_hdr *em_hdr = nla_data(nla); + struct tcf_ematch_ops *em_ops; int data_len = nla_len(nla) - sizeof(*em_hdr); void *data = (void *) em_hdr + sizeof(*em_hdr); struct net *net = dev_net(qdisc_dev(tp->q)); @@ -213,27 +214,29 @@ static int tcf_em_validate(struct tcf_proto *tp, * here. Be aware, the destroy function assumes that the * module is held if the ops field is non zero. */ - em->ops = tcf_em_lookup(em_hdr->kind); + em_ops = tcf_em_lookup(em_hdr->kind); - if (em->ops == NULL) { + if (em_ops == NULL) { err = -ENOENT; #ifdef CONFIG_MODULES __rtnl_unlock(); request_module("ematch-kind-%u", em_hdr->kind); rtnl_lock(); - em->ops = tcf_em_lookup(em_hdr->kind); - if (em->ops) { + em_ops = tcf_em_lookup(em_hdr->kind); + if (em_ops) { /* We dropped the RTNL mutex in order to * perform the module load. Tell the caller * to replay the request. */ - module_put(em->ops->owner); + module_put(em_ops->owner); err = -EAGAIN; } #endif goto errout; } + em->ops = em_ops; + /* ematch module provides expected length of data, so we * can do a basic sanity check. */ -- 2.1.0 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH net] ematch: Fix auto-loading of ematch modules. 2015-02-16 18:13 ` [PATCH net] ematch: Fix auto-loading of ematch modules Ignacy Gawędzki @ 2015-02-16 18:36 ` Cong Wang 2015-02-16 18:50 ` Ignacy Gawędzki 0 siblings, 1 reply; 9+ messages in thread From: Cong Wang @ 2015-02-16 18:36 UTC (permalink / raw) To: Ignacy Gawędzki, netdev On Mon, Feb 16, 2015 at 10:13 AM, Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> wrote: > In tcf_em_validate(), when calling tcf_em_lookup(), don't put the resulting > pointer directly into em->ops, if the function is to possibly return -EAGAIN > after module auto-loading. Otherwise, module_put() will be called by > tcf_em_tree_destroy() on em->ops->owner, while it has already been called by > tcf_em_validate() before return. > Or simply reset em->ops to NULL after module_put()? ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net] ematch: Fix auto-loading of ematch modules. 2015-02-16 18:36 ` Cong Wang @ 2015-02-16 18:50 ` Ignacy Gawędzki 2015-02-17 18:00 ` Cong Wang 0 siblings, 1 reply; 9+ messages in thread From: Ignacy Gawędzki @ 2015-02-16 18:50 UTC (permalink / raw) To: Cong Wang; +Cc: netdev On Mon, Feb 16, 2015 at 10:36:06AM -0800, thus spake Cong Wang: > On Mon, Feb 16, 2015 at 10:13 AM, Ignacy Gawędzki > <ignacy.gawedzki@green-communications.fr> wrote: > > In tcf_em_validate(), when calling tcf_em_lookup(), don't put the resulting > > pointer directly into em->ops, if the function is to possibly return -EAGAIN > > after module auto-loading. Otherwise, module_put() will be called by > > tcf_em_tree_destroy() on em->ops->owner, while it has already been called by > > tcf_em_validate() before return. > > > > Or simply reset em->ops to NULL after module_put()? Yeah, why not. I just got my inspiration from what's done in cls_api.c and act_api.c. What do you think, should the same simplification be applied to cls_api.c? -- Ignacy Gawędzki R&D Engineer Green Communications ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net] ematch: Fix auto-loading of ematch modules. 2015-02-16 18:50 ` Ignacy Gawędzki @ 2015-02-17 18:00 ` Cong Wang 2015-02-17 19:15 ` [PATCH net v2] " Ignacy Gawędzki 0 siblings, 1 reply; 9+ messages in thread From: Cong Wang @ 2015-02-17 18:00 UTC (permalink / raw) To: Ignacy Gawędzki, Cong Wang, netdev On Mon, Feb 16, 2015 at 10:50 AM, Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> wrote: > On Mon, Feb 16, 2015 at 10:36:06AM -0800, thus spake Cong Wang: >> On Mon, Feb 16, 2015 at 10:13 AM, Ignacy Gawędzki >> <ignacy.gawedzki@green-communications.fr> wrote: >> > In tcf_em_validate(), when calling tcf_em_lookup(), don't put the resulting >> > pointer directly into em->ops, if the function is to possibly return -EAGAIN >> > after module auto-loading. Otherwise, module_put() will be called by >> > tcf_em_tree_destroy() on em->ops->owner, while it has already been called by >> > tcf_em_validate() before return. >> > >> >> Or simply reset em->ops to NULL after module_put()? > > Yeah, why not. I just got my inspiration from what's done in cls_api.c and > act_api.c. What do you think, should the same simplification be applied to > cls_api.c? > I prefer the smaller change, we don't have to align with cls_api.c. Yeah, you can always clean it up for net-next. Thanks. ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH net v2] ematch: Fix auto-loading of ematch modules. 2015-02-17 18:00 ` Cong Wang @ 2015-02-17 19:15 ` Ignacy Gawędzki 2015-02-18 5:17 ` Cong Wang 2015-02-20 20:31 ` David Miller 0 siblings, 2 replies; 9+ messages in thread From: Ignacy Gawędzki @ 2015-02-17 19:15 UTC (permalink / raw) To: netdev In tcf_em_validate(), after calling request_module() to load the kind-specific module, set em->ops to NULL before returning -EAGAIN, so that module_put() is not called again by tcf_em_tree_destroy(). Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> --- net/sched/ematch.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/sched/ematch.c b/net/sched/ematch.c index 6742200..fbb7ebf 100644 --- a/net/sched/ematch.c +++ b/net/sched/ematch.c @@ -228,6 +228,7 @@ static int tcf_em_validate(struct tcf_proto *tp, * to replay the request. */ module_put(em->ops->owner); + em->ops = NULL; err = -EAGAIN; } #endif -- 2.1.0 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH net v2] ematch: Fix auto-loading of ematch modules. 2015-02-17 19:15 ` [PATCH net v2] " Ignacy Gawędzki @ 2015-02-18 5:17 ` Cong Wang 2015-02-20 20:31 ` David Miller 1 sibling, 0 replies; 9+ messages in thread From: Cong Wang @ 2015-02-18 5:17 UTC (permalink / raw) To: Ignacy Gawędzki, netdev On Tue, Feb 17, 2015 at 11:15 AM, Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> wrote: > In tcf_em_validate(), after calling request_module() to load the > kind-specific module, set em->ops to NULL before returning -EAGAIN, so > that module_put() is not called again by tcf_em_tree_destroy(). > > Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> Acked-by: Cong Wang <cwang@twopensource.com> ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v2] ematch: Fix auto-loading of ematch modules. 2015-02-17 19:15 ` [PATCH net v2] " Ignacy Gawędzki 2015-02-18 5:17 ` Cong Wang @ 2015-02-20 20:31 ` David Miller 1 sibling, 0 replies; 9+ messages in thread From: David Miller @ 2015-02-20 20:31 UTC (permalink / raw) To: ignacy.gawedzki; +Cc: netdev From: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> Date: Tue, 17 Feb 2015 20:15:20 +0100 > In tcf_em_validate(), after calling request_module() to load the > kind-specific module, set em->ops to NULL before returning -EAGAIN, so > that module_put() is not called again by tcf_em_tree_destroy(). > > Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> Applied and queued up for -stable, thanks. ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2015-02-20 20:31 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-02-16 10:59 Attempt to auto-load em_cmp.ko results in negative module refcnt Ignacy Gawedzki 2015-02-16 15:03 ` Ignacy Gawedzki 2015-02-16 18:13 ` [PATCH net] ematch: Fix auto-loading of ematch modules Ignacy Gawędzki 2015-02-16 18:36 ` Cong Wang 2015-02-16 18:50 ` Ignacy Gawędzki 2015-02-17 18:00 ` Cong Wang 2015-02-17 19:15 ` [PATCH net v2] " Ignacy Gawędzki 2015-02-18 5:17 ` Cong Wang 2015-02-20 20:31 ` David Miller
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.