[Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>

list_for_each_entry_rcu has built-in RCU and lock checking.
Pass cond argument to list_for_each_entry_rcu.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
---
 drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
index 089e201d7550..e6abdbcb4ffb 100644
--- a/drivers/infiniband/hw/hfi1/verbs.c
+++ b/drivers/infiniband/hw/hfi1/verbs.c
@@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
 				       opa_get_lid(packet->dlid, 9B));
 		if (!mcast)
 			goto drop;
-		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
+		list_for_each_entry_rcu(p, &mcast->qp_list, list,
+					lock_is_held(&(ibp->rvp.lock).dep_map)) {
 			packet->qp = p->qp;
 			if (hfi1_do_pkey_check(packet))
 				goto drop;
-- 
2.17.1

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Jason Gunthorpe]

On Wed, Jan 08, 2020 at 12:59:12AM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Pass cond argument to list_for_each_entry_rcu.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> index 089e201d7550..e6abdbcb4ffb 100644
> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>  				       opa_get_lid(packet->dlid, 9B));
>  		if (!mcast)
>  			goto drop;
> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> +		list_for_each_entry_rcu(p, &mcast->qp_list, list,
> +					lock_is_held(&(ibp->rvp.lock).dep_map)) {

Why .dep_map? Does this compile?

Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: Jason Gunthorpe <jgg@ziepe.ca>

On Wed, Jan 08, 2020 at 12:59:12AM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Pass cond argument to list_for_each_entry_rcu.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> index 089e201d7550..e6abdbcb4ffb 100644
> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>  				       opa_get_lid(packet->dlid, 9B));
>  		if (!mcast)
>  			goto drop;
> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> +		list_for_each_entry_rcu(p, &mcast->qp_list, list,
> +					lock_is_held(&(ibp->rvp.lock).dep_map)) {

Why .dep_map? Does this compile?

Alternatively, it can be lockdep_is_held(ibp->rvp.lock).
Please refer to the macro(link below) and let me know if the usage of lock_is_held()
in the patch is correct.

https://elixir.bootlin.com/linux/v5.5-rc2/source/include/linux/lockdep.h#L364

Thanks,
Madhuparna
Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: madhuparnabhowmik04@gmail.com

From: Jason Gunthorpe <jgg@ziepe.ca>

On Wed, Jan 08, 2020 at 12:59:12AM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Pass cond argument to list_for_each_entry_rcu.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> index 089e201d7550..e6abdbcb4ffb 100644
> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>  				       opa_get_lid(packet->dlid, 9B));
>  		if (!mcast)
>  			goto drop;
> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> +		list_for_each_entry_rcu(p, &mcast->qp_list, list,
> +					lock_is_held(&(ibp->rvp.lock).dep_map)) {

Why .dep_map? Does this compile?

Yes, it compiles.

Alternatively, it can be lockdep_is_held(ibp->rvp.lock).
Please refer to the macro(link below) and let me know if the usage of lock_is_held()
in the patch is correct.

https://elixir.bootlin.com/linux/v5.5-rc2/source/include/linux/lockdep.h#L364

Thanks,
Madhuparna

Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Jason Gunthorpe]

On Wed, Jan 08, 2020 at 01:38:50PM +0530, madhuparnabhowmik04@gmail.com wrote:

> Alternatively, it can be lockdep_is_held(ibp->rvp.lock).
> Please refer to the macro(link below) and let me know if the usage of lock_is_held()
> in the patch is correct.

lock_is_held is the normal way to write this

Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Joel Fernandes]

On Wed, Jan 08, 2020 at 01:35:07PM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Jason Gunthorpe <jgg@ziepe.ca>
> 
> On Wed, Jan 08, 2020 at 12:59:12AM +0530, madhuparnabhowmik04@gmail.com wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > 
> > list_for_each_entry_rcu has built-in RCU and lock checking.
> > Pass cond argument to list_for_each_entry_rcu.
> > 
> > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> > index 089e201d7550..e6abdbcb4ffb 100644
> > +++ b/drivers/infiniband/hw/hfi1/verbs.c
> > @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
> >  				       opa_get_lid(packet->dlid, 9B));
> >  		if (!mcast)
> >  			goto drop;
> > -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> > +		list_for_each_entry_rcu(p, &mcast->qp_list, list,
> > +					lock_is_held(&(ibp->rvp.lock).dep_map)) {
> 
> Why .dep_map? Does this compile?

Yeah, have you really compiled this? Don't send patches without at least
compile testing !!

> Alternatively, it can be lockdep_is_held(ibp->rvp.lock).
> Please refer to the macro(link below) and let me know if the usage of lock_is_held()
> in the patch is correct.
> 
> https://elixir.bootlin.com/linux/v5.5-rc2/source/include/linux/lockdep.h#L364

Please use lockdep_is_held(). Thanks.

thanks,

 - Joel

> 
> Thanks,
> Madhuparna
> Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Madhuparna Bhowmik]

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On Fri, Feb 14, 2020 at 10:55 PM Dennis Dalessandro <
dennis.dalessandro@intel.com> wrote:

> On 2/14/2020 10:43 AM, Madhuparna Bhowmik wrote:
> >
> >
> > On Wed, Jan 15, 2020 at 12:05 AM <madhuparnabhowmik04@gmail.com
> > <mailto:madhuparnabhowmik04@gmail.com>> wrote:
> >
> >     From: Dennis Dalessandro <dennis.dalessandro@intel.com
> >     <mailto:dennis.dalessandro@intel.com>>
> >
> >     On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> >      > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> >      >> On Tue, Jan 14, 2020 at 09:53:45PM +0530,
> >      >> madhuparnabhowmik04@gmail.com
> >     <mailto:madhuparnabhowmik04@gmail.com> wrote:
> >      >>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com
> >     <mailto:madhuparnabhowmik04@gmail.com>>
> >      >>>
> >      >>> list_for_each_entry_rcu has built-in RCU and lock checking.
> >      >>> Pass cond argument to list_for_each_entry_rcu.
> >      >>>
> >      >>> Signed-off-by: Madhuparna Bhowmik
> >     <madhuparnabhowmik04@gmail.com <mailto:madhuparnabhowmik04@gmail.com
> >>
> >      >>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
> >      >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >      >>>
> >      >>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> >      >>> b/drivers/infiniband/hw/hfi1/verbs.c
> >      >>> index 089e201d7550..22f2d4fd2577 100644
> >      >>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> >      >>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
> >      >>> hfi1_packet *packet,
> >      >>>                          opa_get_lid(packet->dlid, 9B));
> >      >>>           if (!mcast)
> >      >>>               goto drop;
> >      >>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> >      >>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
> >      >>> lockdep_is_held(&(ibp->rvp.lock))) {
> >      >>
> >      >> Okay, this looks reasonable
> >      >>
> >      >> Mike, Dennis, is this the right lock to test?
> >      >>
> >      >
> >      > I'm looking at that right now actually, I don't think this is
> >     correct.
> >      > Wanted to talk to Mike before I send a response though.
> >      >
> >      > -Denny
> >
> >     That's definitely going to throw a ton of lock dep messages. It's not
> >     really the right lock either. Instead what we probably need to do is
> >     what we do in the non-multicast part of the code and take the
> >     rcu_read_lock().
> >
> >     I'd say hold off on this and we'll fix it right. Same goes for the
> >     qib one.
> >
> >     Alright, thank you for reviewing.
> >
> >     The rdmavt one though looks to be OK. I'll give it a test.
> >
> > Hi,
> > I just wanted to follow up on this.
> > Any updates?
> > Also, is the bug fixed now?
> >
> > Thank you,
> > Madhuparna
> >
> >     Thank you,
> >     Madhuparna
> >
> >     -Denny
> >
>
> I've got a patch going through internal discussion and testing for
> adding rcu read locking.
>
> The RDMAVT patch, I was OK with going in, I guess I just mentioned that
> in a reply rather than adding an RB tag. Let me go ahead and do that.
>
> Thank you very much for the update and Reviewed By.

Regards,
Madhuparna

-Denny
>

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Dennis Dalessandro]

On 2/14/2020 10:43 AM, Madhuparna Bhowmik wrote:
> 
> 
> On Wed, Jan 15, 2020 at 12:05 AM <madhuparnabhowmik04@gmail.com 
> <mailto:madhuparnabhowmik04@gmail.com>> wrote:
> 
>     From: Dennis Dalessandro <dennis.dalessandro@intel.com
>     <mailto:dennis.dalessandro@intel.com>>
> 
>     On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
>      > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
>      >> On Tue, Jan 14, 2020 at 09:53:45PM +0530,
>      >> madhuparnabhowmik04@gmail.com
>     <mailto:madhuparnabhowmik04@gmail.com> wrote:
>      >>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com
>     <mailto:madhuparnabhowmik04@gmail.com>>
>      >>>
>      >>> list_for_each_entry_rcu has built-in RCU and lock checking.
>      >>> Pass cond argument to list_for_each_entry_rcu.
>      >>>
>      >>> Signed-off-by: Madhuparna Bhowmik
>     <madhuparnabhowmik04@gmail.com <mailto:madhuparnabhowmik04@gmail.com>>
>      >>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>      >>>   1 file changed, 1 insertion(+), 1 deletion(-)
>      >>>
>      >>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c
>      >>> b/drivers/infiniband/hw/hfi1/verbs.c
>      >>> index 089e201d7550..22f2d4fd2577 100644
>      >>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
>      >>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
>      >>> hfi1_packet *packet,
>      >>>                          opa_get_lid(packet->dlid, 9B));
>      >>>           if (!mcast)
>      >>>               goto drop;
>      >>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
>      >>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
>      >>> lockdep_is_held(&(ibp->rvp.lock))) {
>      >>
>      >> Okay, this looks reasonable
>      >>
>      >> Mike, Dennis, is this the right lock to test?
>      >>
>      >
>      > I'm looking at that right now actually, I don't think this is
>     correct.
>      > Wanted to talk to Mike before I send a response though.
>      >
>      > -Denny
> 
>     That's definitely going to throw a ton of lock dep messages. It's not
>     really the right lock either. Instead what we probably need to do is
>     what we do in the non-multicast part of the code and take the
>     rcu_read_lock().
> 
>     I'd say hold off on this and we'll fix it right. Same goes for the
>     qib one.
> 
>     Alright, thank you for reviewing.
> 
>     The rdmavt one though looks to be OK. I'll give it a test.
> 
> Hi,
> I just wanted to follow up on this.
> Any updates?
> Also, is the bug fixed now?
> 
> Thank you,
> Madhuparna
> 
>     Thank you,
>     Madhuparna
> 
>     -Denny
> 

I've got a patch going through internal discussion and testing for 
adding rcu read locking.

The RDMAVT patch, I was OK with going in, I guess I just mentioned that 
in a reply rather than adding an RB tag. Let me go ahead and do that.

-Denny
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Madhuparna Bhowmik]

[-- Attachment #1.1: Type: text/plain, Size: 2096 bytes --]

On Wed, Jan 15, 2020 at 12:05 AM <madhuparnabhowmik04@gmail.com> wrote:

> From: Dennis Dalessandro <dennis.dalessandro@intel.com>
>
> On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> >> On Tue, Jan 14, 2020 at 09:53:45PM +0530,
> >> madhuparnabhowmik04@gmail.com wrote:
> >>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >>>
> >>> list_for_each_entry_rcu has built-in RCU and lock checking.
> >>> Pass cond argument to list_for_each_entry_rcu.
> >>>
> >>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> >>> b/drivers/infiniband/hw/hfi1/verbs.c
> >>> index 089e201d7550..22f2d4fd2577 100644
> >>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> >>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
> >>> hfi1_packet *packet,
> >>>                          opa_get_lid(packet->dlid, 9B));
> >>>           if (!mcast)
> >>>               goto drop;
> >>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> >>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
> >>> lockdep_is_held(&(ibp->rvp.lock))) {
> >>
> >> Okay, this looks reasonable
> >>
> >> Mike, Dennis, is this the right lock to test?
> >>
> >
> > I'm looking at that right now actually, I don't think this is correct.
> > Wanted to talk to Mike before I send a response though.
> >
> > -Denny
>
> That's definitely going to throw a ton of lock dep messages. It's not
> really the right lock either. Instead what we probably need to do is
> what we do in the non-multicast part of the code and take the
> rcu_read_lock().
>
> I'd say hold off on this and we'll fix it right. Same goes for the qib one.
>
> Alright, thank you for reviewing.
>
> The rdmavt one though looks to be OK. I'll give it a test.
>
> Hi,
I just wanted to follow up on this.
Any updates?
Also, is the bug fixed now?

Thank you,
Madhuparna



> Thank you,
> Madhuparna
>
> -Denny
>

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Dennis Dalessandro]

On 1/14/2020 2:41 PM, Jason Gunthorpe wrote:
> On Tue, Jan 14, 2020 at 01:24:00PM -0500, Dennis Dalessandro wrote:
>> On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
>>> On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
>>>> On Tue, Jan 14, 2020 at 09:53:45PM +0530,
>>>> madhuparnabhowmik04@gmail.com wrote:
>>>>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>>>
>>>>> list_for_each_entry_rcu has built-in RCU and lock checking.
>>>>> Pass cond argument to list_for_each_entry_rcu.
>>>>>
>>>>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>>>    drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c
>>>>> b/drivers/infiniband/hw/hfi1/verbs.c
>>>>> index 089e201d7550..22f2d4fd2577 100644
>>>>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
>>>>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
>>>>> hfi1_packet *packet,
>>>>>                           opa_get_lid(packet->dlid, 9B));
>>>>>            if (!mcast)
>>>>>                goto drop;
>>>>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
>>>>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
>>>>> lockdep_is_held(&(ibp->rvp.lock))) {
>>>>
>>>> Okay, this looks reasonable
>>>>
>>>> Mike, Dennis, is this the right lock to test?
>>>>
>>>
>>> I'm looking at that right now actually, I don't think this is correct.
>>> Wanted to talk to Mike before I send a response though.
>>>
>>> -Denny
>>
>> That's definitely going to throw a ton of lock dep messages. It's not really
>> the right lock either. Instead what we probably need to do is what we do in
>> the non-multicast part of the code and take the rcu_read_lock().
> 
> Uh.. why is this using the _rcu varient without holding the rcu lock?
> That is quite wrong already.
>

Yep, seems like a bug to me. Patch forthcoming.

-Denny

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Jason Gunthorpe]

On Tue, Jan 14, 2020 at 01:24:00PM -0500, Dennis Dalessandro wrote:
> On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> > > On Tue, Jan 14, 2020 at 09:53:45PM +0530,
> > > madhuparnabhowmik04@gmail.com wrote:
> > > > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > > > 
> > > > list_for_each_entry_rcu has built-in RCU and lock checking.
> > > > Pass cond argument to list_for_each_entry_rcu.
> > > > 
> > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > > >   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
> > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> > > > b/drivers/infiniband/hw/hfi1/verbs.c
> > > > index 089e201d7550..22f2d4fd2577 100644
> > > > +++ b/drivers/infiniband/hw/hfi1/verbs.c
> > > > @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
> > > > hfi1_packet *packet,
> > > >                          opa_get_lid(packet->dlid, 9B));
> > > >           if (!mcast)
> > > >               goto drop;
> > > > -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> > > > +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
> > > > lockdep_is_held(&(ibp->rvp.lock))) {
> > > 
> > > Okay, this looks reasonable
> > > 
> > > Mike, Dennis, is this the right lock to test?
> > > 
> > 
> > I'm looking at that right now actually, I don't think this is correct.
> > Wanted to talk to Mike before I send a response though.
> > 
> > -Denny
> 
> That's definitely going to throw a ton of lock dep messages. It's not really
> the right lock either. Instead what we probably need to do is what we do in
> the non-multicast part of the code and take the rcu_read_lock().

Uh.. why is this using the _rcu varient without holding the rcu lock?
That is quite wrong already.

Jason
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Joel Fernandes]

On Wed, Jan 15, 2020 at 12:04:58AM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Dennis Dalessandro <dennis.dalessandro@intel.com>
> 
> On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> > > On Tue, Jan 14, 2020 at 09:53:45PM +0530,
> > > madhuparnabhowmik04@gmail.com wrote:
> > > > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > > > 
> > > > list_for_each_entry_rcu has built-in RCU and lock checking.
> > > > Pass cond argument to list_for_each_entry_rcu.
> > > > 
> > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > > >   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
> > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> > > > b/drivers/infiniband/hw/hfi1/verbs.c
> > > > index 089e201d7550..22f2d4fd2577 100644
> > > > +++ b/drivers/infiniband/hw/hfi1/verbs.c
> > > > @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
> > > > hfi1_packet *packet,
> > > >                          opa_get_lid(packet->dlid, 9B));
> > > >           if (!mcast)
> > > >               goto drop;
> > > > -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> > > > +        list_for_each_entry_rcu(p, &mcast->qp_list, list,
> > > > lockdep_is_held(&(ibp->rvp.lock))) {
> > > 
> > > Okay, this looks reasonable
> > > 
> > > Mike, Dennis, is this the right lock to test?
> > > 
> > 
> > I'm looking at that right now actually, I don't think this is correct.
> > Wanted to talk to Mike before I send a response though.
> > 
> > -Denny
> 
> That's definitely going to throw a ton of lock dep messages. It's not really
> the right lock either. Instead what we probably need to do is what we do in
> the non-multicast part of the code and take the rcu_read_lock().
> 
> I'd say hold off on this and we'll fix it right. Same goes for the qib one.
> 
> Alright, thank you for reviewing.
> 
> The rdmavt one though looks to be OK. I'll give it a test.

Madhuparna, there seems to be an issue with your mail client where it is not
quoting text correctly, either there is a '>' missing or there are too many.
Can you look into it and figure what's wrong with it?

thanks,

 - Joel

> 
> Thank you,
> Madhuparna
> 
> -Denny
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: Dennis Dalessandro <dennis.dalessandro@intel.com>

On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
>> On Tue, Jan 14, 2020 at 09:53:45PM +0530, 
>> madhuparnabhowmik04@gmail.com wrote:
>>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>
>>> list_for_each_entry_rcu has built-in RCU and lock checking.
>>> Pass cond argument to list_for_each_entry_rcu.
>>>
>>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c 
>>> b/drivers/infiniband/hw/hfi1/verbs.c
>>> index 089e201d7550..22f2d4fd2577 100644
>>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
>>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct 
>>> hfi1_packet *packet,
>>>                          opa_get_lid(packet->dlid, 9B));
>>>           if (!mcast)
>>>               goto drop;
>>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
>>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list, 
>>> lockdep_is_held(&(ibp->rvp.lock))) {
>>
>> Okay, this looks reasonable
>>
>> Mike, Dennis, is this the right lock to test?
>>
> 
> I'm looking at that right now actually, I don't think this is correct. 
> Wanted to talk to Mike before I send a response though.
> 
> -Denny

That's definitely going to throw a ton of lock dep messages. It's not 
really the right lock either. Instead what we probably need to do is 
what we do in the non-multicast part of the code and take the 
rcu_read_lock().

I'd say hold off on this and we'll fix it right. Same goes for the qib one.

Alright, thank you for reviewing.

The rdmavt one though looks to be OK. I'll give it a test.

Thank you,
Madhuparna

-Denny
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Dennis Dalessandro]

On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
>> On Tue, Jan 14, 2020 at 09:53:45PM +0530, 
>> madhuparnabhowmik04@gmail.com wrote:
>>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>
>>> list_for_each_entry_rcu has built-in RCU and lock checking.
>>> Pass cond argument to list_for_each_entry_rcu.
>>>
>>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c 
>>> b/drivers/infiniband/hw/hfi1/verbs.c
>>> index 089e201d7550..22f2d4fd2577 100644
>>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
>>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct 
>>> hfi1_packet *packet,
>>>                          opa_get_lid(packet->dlid, 9B));
>>>           if (!mcast)
>>>               goto drop;
>>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) {
>>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list, 
>>> lockdep_is_held(&(ibp->rvp.lock))) {
>>
>> Okay, this looks reasonable
>>
>> Mike, Dennis, is this the right lock to test?
>>
> 
> I'm looking at that right now actually, I don't think this is correct. 
> Wanted to talk to Mike before I send a response though.
> 
> -Denny

That's definitely going to throw a ton of lock dep messages. It's not 
really the right lock either. Instead what we probably need to do is 
what we do in the non-multicast part of the code and take the 
rcu_read_lock().

I'd say hold off on this and we'll fix it right. Same goes for the qib one.

The rdmavt one though looks to be OK. I'll give it a test.

-Denny
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Dennis Dalessandro]

On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> On Tue, Jan 14, 2020 at 09:53:45PM +0530, madhuparnabhowmik04@gmail.com wrote:
>> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>
>> list_for_each_entry_rcu has built-in RCU and lock checking.
>> Pass cond argument to list_for_each_entry_rcu.
>>
>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
>> index 089e201d7550..22f2d4fd2577 100644
>> +++ b/drivers/infiniband/hw/hfi1/verbs.c
>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>>   				       opa_get_lid(packet->dlid, 9B));
>>   		if (!mcast)
>>   			goto drop;
>> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
>> +		list_for_each_entry_rcu(p, &mcast->qp_list, list, lockdep_is_held(&(ibp->rvp.lock))) {
> 
> Okay, this looks reasonable
> 
> Mike, Dennis, is this the right lock to test?
> 

I'm looking at that right now actually, I don't think this is correct. 
Wanted to talk to Mike before I send a response though.

-Denny
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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Jason Gunthorpe]

On Tue, Jan 14, 2020 at 09:53:45PM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Pass cond argument to list_for_each_entry_rcu.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>  drivers/infiniband/hw/hfi1/verbs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> index 089e201d7550..22f2d4fd2577 100644
> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>  				       opa_get_lid(packet->dlid, 9B));
>  		if (!mcast)
>  			goto drop;
> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> +		list_for_each_entry_rcu(p, &mcast->qp_list, list, lockdep_is_held(&(ibp->rvp.lock))) {

Okay, this looks reasonable

Mike, Dennis, is this the right lock to test?

Jason
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[Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>

list_for_each_entry_rcu has built-in RCU and lock checking.
Pass cond argument to list_for_each_entry_rcu.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
---
 drivers/infiniband/hw/hfi1/verbs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
index 089e201d7550..22f2d4fd2577 100644
--- a/drivers/infiniband/hw/hfi1/verbs.c
+++ b/drivers/infiniband/hw/hfi1/verbs.c
@@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
 				       opa_get_lid(packet->dlid, 9B));
 		if (!mcast)
 			goto drop;
-		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
+		list_for_each_entry_rcu(p, &mcast->qp_list, list, lockdep_is_held(&(ibp->rvp.lock))) {
 			packet->qp = p->qp;
 			if (hfi1_do_pkey_check(packet))
 				goto drop;
-- 
2.17.1

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Madhuparna Bhowmik]

[-- Attachment #1.1: Type: text/plain, Size: 1433 bytes --]

On Tue, Jan 7, 2020 at 11:56 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:

> On Tue, Jan 07, 2020 at 11:05:08PM +0530, madhuparnabhowmik04@gmail.com
> wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >
> > list_for_each_entry_rcu has built-in RCU and lock checking.
> > Pass cond argument to list_for_each_entry_rcu.
> >
> > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> b/drivers/infiniband/hw/hfi1/verbs.c
> > index 089e201d7550..cab2ff185240 100644
> > +++ b/drivers/infiniband/hw/hfi1/verbs.c
> > @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct
> hfi1_packet *packet,
> >                                      opa_get_lid(packet->dlid, 9B));
> >               if (!mcast)
> >                       goto drop;
> > -             list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> > +             list_for_each_entry_rcu(p, &mcast->qp_list, list
> > +
>  lock_is_held(&(ibp->rvp.lock).dep_map)) {
>
> This is missing a ',' and isn't indented properly. Does it even
> compile?
>
> I am really sorry about this, I will resend this patch.
Yes, it compiles, though I guess after testing I edited it by mistake.

Thanks,
Madhuparna


> The idea seems sound though.
>
> Jason
>
ᐧ

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Re: [Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[Jason Gunthorpe]

On Tue, Jan 07, 2020 at 11:05:08PM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Pass cond argument to list_for_each_entry_rcu.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
>  drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
> index 089e201d7550..cab2ff185240 100644
> +++ b/drivers/infiniband/hw/hfi1/verbs.c
> @@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
>  				       opa_get_lid(packet->dlid, 9B));
>  		if (!mcast)
>  			goto drop;
> -		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> +		list_for_each_entry_rcu(p, &mcast->qp_list, list
> +								lock_is_held(&(ibp->rvp.lock).dep_map)) {

This is missing a ',' and isn't indented properly. Does it even
compile?

The idea seems sound though.

Jason
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[Linux-kernel-mentees] [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking

[madhuparnabhowmik04]

From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>

list_for_each_entry_rcu has built-in RCU and lock checking.
Pass cond argument to list_for_each_entry_rcu.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
---
 drivers/infiniband/hw/hfi1/verbs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
index 089e201d7550..cab2ff185240 100644
--- a/drivers/infiniband/hw/hfi1/verbs.c
+++ b/drivers/infiniband/hw/hfi1/verbs.c
@@ -515,7 +515,8 @@ static inline void hfi1_handle_packet(struct hfi1_packet *packet,
 				       opa_get_lid(packet->dlid, 9B));
 		if (!mcast)
 			goto drop;
-		list_for_each_entry_rcu(p, &mcast->qp_list, list) {
+		list_for_each_entry_rcu(p, &mcast->qp_list, list
+								lock_is_held(&(ibp->rvp.lock).dep_map)) {
 			packet->qp = p->qp;
 			if (hfi1_do_pkey_check(packet))
 				goto drop;
-- 
2.17.1

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