RE: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
> -Original Message- > From: Derek Su > Sent: Wednesday, March 25, 2020 12:17 PM > To: Zhang, Chen > Cc: qemu-devel@nongnu.org; lizhij...@cn.fujitsu.com; > jasow...@redhat.com; dere...@qnap.com > Subject: Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in > packet_enqueue() > > Jing-Wei Su 於 2020年3月25日 週三 上午10:05 > 寫道： > > > > Zhang, Chen 於 2020年3月25日 週三 上午 > 9:37寫道： > > > > > > > > > > > > > -Original Message- > > > > From: Jing-Wei Su > > > > Sent: Tuesday, March 24, 2020 10:47 AM > > > > To: Zhang, Chen > > > > Cc: qemu-devel@nongnu.org; lizhij...@cn.fujitsu.com; > > > > jasow...@redhat.com; dere...@qnap.com > > > > Subject: Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in > > > > packet_enqueue() > > > > > > > > Zhang, Chen 於 2020年3月24日 週二 上午 > 3:24 > > > > 寫道： > > > > > > > > > > > > > > > > > > > > > -Original Message- > > > > > > From: Derek Su > > > > > > Sent: Monday, March 23, 2020 1:48 AM > > > > > > To: qemu-devel@nongnu.org > > > > > > Cc: Zhang, Chen ; > > > > > > lizhij...@cn.fujitsu.com; jasow...@redhat.com; > > > > > > dere...@qnap.com > > > > > > Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in > > > > > > packet_enqueue() > > > > > > > > > > > > The patch is to fix the "pkt" memory leak in packet_enqueue(). > > > > > > The allocated "pkt" needs to be freed if the colo compare > > > > > > primary or secondary queue is too big. > > > > > > > > > > Hi Derek, > > > > > > > > > > Thank you for the patch. > > > > > I re-think this issue in a big view, looks just free the pkg is > > > > > not enough in > > > > this situation. > > > > > The root cause is network is too busy to compare, So, better > > > > > choice is notify COLO frame to do a checkpoint and clean up all > > > > > the network queue. This work maybe decrease COLO network > > > > > performance but seams > > > > better than drop lots of pkg. > > > > > > > > > > Thanks > > > > > Zhang Chen > > > > > > > > > > > > > Hello, Zhang > > > > > > > > Got it. > > > > What is the concern of the massive "drop packets"? > > > > Does the behavior make the COLO do checkpoint periodically (~20 > > > > seconds) instead of doing immediate checkpoint when encountering > > > > different response packets? > > > > > > The concern of the "drop packets" is guest will lose network > > > connection with most of real clients until next periodic force > > > checkpoint. COLO designed for dynamic control checkpoint, so I think do > a checkpoint here will help guest supply service faster. > > > > > > > I see. > > I'll update the patch with your suggestion later. > > > > Hi, Zhang > Here is the idea and pseudo code to handle the "drop packet". > > ``` > ret = packet_enqueue > (1) ret == 0 > compare connection > (2) ret == -1 > send packet > (3) ret == queue insertion fail > do checkpoint > send all queued primary packets > remove all queued secondary packets ``` > > Do you have any comment for the handling? Looks good for me. Thanks Zhang Chen > > Thanks > Derek > > > > > > > > > It seems that frequent checkpoints caused by the full queue (busy > > > > network) instead of different > > > > response packets may harm the high speed network (10 Gbps or > > > > higher) performance dramatically. > > > > > > Yes, maybe I can send a patch to make user adjust queue size depend on > it's own environment. > > > But with larger queue size, colo-compare will spend much time to do > > > compare packet when network Is real busy status. > > > > Thank you. The user-configurable queue size will be very helpful. > > > > Thanks. > > Derek Su > > > > > > > > Thanks > > > Zhang Chen > > > > > > > > > > > Thanks > > > > Derek > > > > > > > > > &
Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
Jing-Wei Su 於 2020年3月25日 週三 上午10:05寫道：
>
> Zhang, Chen 於 2020年3月25日 週三 上午9:37寫道：
> >
> >
> >
> > > -Original Message-
> > > From: Jing-Wei Su
> > > Sent: Tuesday, March 24, 2020 10:47 AM
> > > To: Zhang, Chen
> > > Cc: qemu-devel@nongnu.org; lizhij...@cn.fujitsu.com;
> > > jasow...@redhat.com; dere...@qnap.com
> > > Subject: Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > > packet_enqueue()
> > >
> > > Zhang, Chen 於 2020年3月24日 週二 上午3:24
> > > 寫道：
> > > >
> > > >
> > > >
> > > > > -Original Message-
> > > > > From: Derek Su
> > > > > Sent: Monday, March 23, 2020 1:48 AM
> > > > > To: qemu-devel@nongnu.org
> > > > > Cc: Zhang, Chen ; lizhij...@cn.fujitsu.com;
> > > > > jasow...@redhat.com; dere...@qnap.com
> > > > > Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > > > > packet_enqueue()
> > > > >
> > > > > The patch is to fix the "pkt" memory leak in packet_enqueue().
> > > > > The allocated "pkt" needs to be freed if the colo compare primary or
> > > > > secondary queue is too big.
> > > >
> > > > Hi Derek,
> > > >
> > > > Thank you for the patch.
> > > > I re-think this issue in a big view, looks just free the pkg is not
> > > > enough in
> > > this situation.
> > > > The root cause is network is too busy to compare, So, better choice is
> > > > notify COLO frame to do a checkpoint and clean up all the network
> > > > queue. This work maybe decrease COLO network performance but seams
> > > better than drop lots of pkg.
> > > >
> > > > Thanks
> > > > Zhang Chen
> > > >
> > >
> > > Hello, Zhang
> > >
> > > Got it.
> > > What is the concern of the massive "drop packets"?
> > > Does the behavior make the COLO do checkpoint periodically (~20 seconds)
> > > instead of doing immediate checkpoint when encountering different
> > > response packets?
> >
> > The concern of the "drop packets" is guest will lose network connection with
> > most of real clients until next periodic force checkpoint. COLO designed
> > for dynamic
> > control checkpoint, so I think do a checkpoint here will help guest supply
> > service faster.
> >
>
> I see.
> I'll update the patch with your suggestion later.
>
Hi, Zhang
Here is the idea and pseudo code to handle the "drop packet".
```
ret = packet_enqueue
(1) ret == 0
compare connection
(2) ret == -1
send packet
(3) ret == queue insertion fail
do checkpoint
send all queued primary packets
remove all queued secondary packets
```
Do you have any comment for the handling?
Thanks
Derek
> > >
> > > It seems that frequent checkpoints caused by the full queue (busy
> > > network) instead of different
> > > response packets may harm the high speed network (10 Gbps or higher)
> > > performance dramatically.
> >
> > Yes, maybe I can send a patch to make user adjust queue size depend on it's
> > own environment.
> > But with larger queue size, colo-compare will spend much time to do compare
> > packet when network
> > Is real busy status.
>
> Thank you. The user-configurable queue size will be very helpful.
>
> Thanks.
> Derek Su
>
> >
> > Thanks
> > Zhang Chen
> >
> > >
> > > Thanks
> > > Derek
> > >
> > > > >
> > > > > Signed-off-by: Derek Su
> > > > > ---
> > > > > net/colo-compare.c | 23 +++
> > > > > 1 file changed, 15 insertions(+), 8 deletions(-)
> > > > >
> > > > > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > > > > 7ee17f2cf8..cdd87b2aa8 100644
> > > > > --- a/net/colo-compare.c
> > > > > +++ b/net/colo-compare.c
> > > > > @@ -120,6 +120,10 @@ enum {
> > > > > SECONDARY_IN,
> > > > > };
> > > > >
> > > > > +static const char *colo_mode[] = {
> > > > > +[PRIMARY_IN] = "primary",
> > > > > +[SECONDARY_IN] = "secondary",
> > > > > +};
> > > > >
> > > > > static
Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
Zhang, Chen 於 2020年3月25日 週三 上午9:37寫道：
>
>
>
> > -Original Message-
> > From: Jing-Wei Su
> > Sent: Tuesday, March 24, 2020 10:47 AM
> > To: Zhang, Chen
> > Cc: qemu-devel@nongnu.org; lizhij...@cn.fujitsu.com;
> > jasow...@redhat.com; dere...@qnap.com
> > Subject: Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > packet_enqueue()
> >
> > Zhang, Chen 於 2020年3月24日 週二 上午3:24
> > 寫道：
> > >
> > >
> > >
> > > > -Original Message-
> > > > From: Derek Su
> > > > Sent: Monday, March 23, 2020 1:48 AM
> > > > To: qemu-devel@nongnu.org
> > > > Cc: Zhang, Chen ; lizhij...@cn.fujitsu.com;
> > > > jasow...@redhat.com; dere...@qnap.com
> > > > Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > > > packet_enqueue()
> > > >
> > > > The patch is to fix the "pkt" memory leak in packet_enqueue().
> > > > The allocated "pkt" needs to be freed if the colo compare primary or
> > > > secondary queue is too big.
> > >
> > > Hi Derek,
> > >
> > > Thank you for the patch.
> > > I re-think this issue in a big view, looks just free the pkg is not
> > > enough in
> > this situation.
> > > The root cause is network is too busy to compare, So, better choice is
> > > notify COLO frame to do a checkpoint and clean up all the network
> > > queue. This work maybe decrease COLO network performance but seams
> > better than drop lots of pkg.
> > >
> > > Thanks
> > > Zhang Chen
> > >
> >
> > Hello, Zhang
> >
> > Got it.
> > What is the concern of the massive "drop packets"?
> > Does the behavior make the COLO do checkpoint periodically (~20 seconds)
> > instead of doing immediate checkpoint when encountering different
> > response packets?
>
> The concern of the "drop packets" is guest will lose network connection with
> most of real clients until next periodic force checkpoint. COLO designed for
> dynamic
> control checkpoint, so I think do a checkpoint here will help guest supply
> service faster.
>
I see.
I'll update the patch with your suggestion later.
> >
> > It seems that frequent checkpoints caused by the full queue (busy
> > network) instead of different
> > response packets may harm the high speed network (10 Gbps or higher)
> > performance dramatically.
>
> Yes, maybe I can send a patch to make user adjust queue size depend on it's
> own environment.
> But with larger queue size, colo-compare will spend much time to do compare
> packet when network
> Is real busy status.
Thank you. The user-configurable queue size will be very helpful.
Thanks.
Derek Su
>
> Thanks
> Zhang Chen
>
> >
> > Thanks
> > Derek
> >
> > > >
> > > > Signed-off-by: Derek Su
> > > > ---
> > > > net/colo-compare.c | 23 +++
> > > > 1 file changed, 15 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > > > 7ee17f2cf8..cdd87b2aa8 100644
> > > > --- a/net/colo-compare.c
> > > > +++ b/net/colo-compare.c
> > > > @@ -120,6 +120,10 @@ enum {
> > > > SECONDARY_IN,
> > > > };
> > > >
> > > > +static const char *colo_mode[] = {
> > > > +[PRIMARY_IN] = "primary",
> > > > +[SECONDARY_IN] = "secondary",
> > > > +};
> > > >
> > > > static int compare_chr_send(CompareState *s,
> > > > const uint8_t *buf, @@ -215,6 +219,7 @@
> > > > static int packet_enqueue(CompareState *s, int mode, Connection
> > **con)
> > > > ConnectionKey key;
> > > > Packet *pkt = NULL;
> > > > Connection *conn;
> > > > +int ret;
> > > >
> > > > if (mode == PRIMARY_IN) {
> > > > pkt = packet_new(s->pri_rs.buf, @@ -243,16 +248,18 @@
> > > > static int packet_enqueue(CompareState *s, int mode, Connection
> > **con)
> > > > }
> > > >
> > > > if (mode == PRIMARY_IN) {
> > > > -if (!colo_insert_packet(>primary_list, pkt,
> > > > >pack)) {
> > > > -error_report("colo compare primary queue size too big,"
> > > > - "drop packet");
> > > > -}
> > > > +ret = colo_insert_packet(>primary_list, pkt,
> > > > + >pack);
> > > > } else {
> > > > -if (!colo_insert_packet(>secondary_list, pkt,
> > > > >sack)) {
> > > > -error_report("colo compare secondary queue size too big,"
> > > > - "drop packet");
> > > > -}
> > > > +ret = colo_insert_packet(>secondary_list, pkt,
> > > > + >sack);
> > > > }
> > > > +
> > > > +if (!ret) {
> > > > +error_report("colo compare %s queue size too big,"
> > > > + "drop packet", colo_mode[mode]);
> > > > +packet_destroy(pkt, NULL);
> > > > +pkt = NULL;
> > > > +}
> > > > +
> > > > *con = conn;
> > > >
> > > > return 0;
> > > > --
> > > > 2.17.1
> > >
RE: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
> -Original Message-
> From: Jing-Wei Su
> Sent: Tuesday, March 24, 2020 10:47 AM
> To: Zhang, Chen
> Cc: qemu-devel@nongnu.org; lizhij...@cn.fujitsu.com;
> jasow...@redhat.com; dere...@qnap.com
> Subject: Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> packet_enqueue()
>
> Zhang, Chen 於 2020年3月24日 週二 上午3:24
> 寫道：
> >
> >
> >
> > > -Original Message-
> > > From: Derek Su
> > > Sent: Monday, March 23, 2020 1:48 AM
> > > To: qemu-devel@nongnu.org
> > > Cc: Zhang, Chen ; lizhij...@cn.fujitsu.com;
> > > jasow...@redhat.com; dere...@qnap.com
> > > Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > > packet_enqueue()
> > >
> > > The patch is to fix the "pkt" memory leak in packet_enqueue().
> > > The allocated "pkt" needs to be freed if the colo compare primary or
> > > secondary queue is too big.
> >
> > Hi Derek,
> >
> > Thank you for the patch.
> > I re-think this issue in a big view, looks just free the pkg is not enough
> > in
> this situation.
> > The root cause is network is too busy to compare, So, better choice is
> > notify COLO frame to do a checkpoint and clean up all the network
> > queue. This work maybe decrease COLO network performance but seams
> better than drop lots of pkg.
> >
> > Thanks
> > Zhang Chen
> >
>
> Hello, Zhang
>
> Got it.
> What is the concern of the massive "drop packets"?
> Does the behavior make the COLO do checkpoint periodically (~20 seconds)
> instead of doing immediate checkpoint when encountering different
> response packets?
The concern of the "drop packets" is guest will lose network connection with
most of real clients until next periodic force checkpoint. COLO designed for
dynamic
control checkpoint, so I think do a checkpoint here will help guest supply
service faster.
>
> It seems that frequent checkpoints caused by the full queue (busy
> network) instead of different
> response packets may harm the high speed network (10 Gbps or higher)
> performance dramatically.
Yes, maybe I can send a patch to make user adjust queue size depend on it's own
environment.
But with larger queue size, colo-compare will spend much time to do compare
packet when network
Is real busy status.
Thanks
Zhang Chen
>
> Thanks
> Derek
>
> > >
> > > Signed-off-by: Derek Su
> > > ---
> > > net/colo-compare.c | 23 +++
> > > 1 file changed, 15 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > > 7ee17f2cf8..cdd87b2aa8 100644
> > > --- a/net/colo-compare.c
> > > +++ b/net/colo-compare.c
> > > @@ -120,6 +120,10 @@ enum {
> > > SECONDARY_IN,
> > > };
> > >
> > > +static const char *colo_mode[] = {
> > > +[PRIMARY_IN] = "primary",
> > > +[SECONDARY_IN] = "secondary",
> > > +};
> > >
> > > static int compare_chr_send(CompareState *s,
> > > const uint8_t *buf, @@ -215,6 +219,7 @@
> > > static int packet_enqueue(CompareState *s, int mode, Connection
> **con)
> > > ConnectionKey key;
> > > Packet *pkt = NULL;
> > > Connection *conn;
> > > +int ret;
> > >
> > > if (mode == PRIMARY_IN) {
> > > pkt = packet_new(s->pri_rs.buf, @@ -243,16 +248,18 @@
> > > static int packet_enqueue(CompareState *s, int mode, Connection
> **con)
> > > }
> > >
> > > if (mode == PRIMARY_IN) {
> > > -if (!colo_insert_packet(>primary_list, pkt, >pack)) {
> > > -error_report("colo compare primary queue size too big,"
> > > - "drop packet");
> > > -}
> > > +ret = colo_insert_packet(>primary_list, pkt,
> > > + >pack);
> > > } else {
> > > -if (!colo_insert_packet(>secondary_list, pkt,
> > > >sack)) {
> > > -error_report("colo compare secondary queue size too big,"
> > > - "drop packet");
> > > -}
> > > +ret = colo_insert_packet(>secondary_list, pkt,
> > > + >sack);
> > > }
> > > +
> > > +if (!ret) {
> > > +error_report("colo compare %s queue size too big,"
> > > + "drop packet", colo_mode[mode]);
> > > +packet_destroy(pkt, NULL);
> > > +pkt = NULL;
> > > +}
> > > +
> > > *con = conn;
> > >
> > > return 0;
> > > --
> > > 2.17.1
> >
Re: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
Zhang, Chen 於 2020年3月24日 週二 上午3:24寫道：
>
>
>
> > -Original Message-
> > From: Derek Su
> > Sent: Monday, March 23, 2020 1:48 AM
> > To: qemu-devel@nongnu.org
> > Cc: Zhang, Chen ; lizhij...@cn.fujitsu.com;
> > jasow...@redhat.com; dere...@qnap.com
> > Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> > packet_enqueue()
> >
> > The patch is to fix the "pkt" memory leak in packet_enqueue().
> > The allocated "pkt" needs to be freed if the colo compare primary or
> > secondary queue is too big.
>
> Hi Derek,
>
> Thank you for the patch.
> I re-think this issue in a big view, looks just free the pkg is not enough in
> this situation.
> The root cause is network is too busy to compare, So, better choice is notify
> COLO frame
> to do a checkpoint and clean up all the network queue. This work maybe
> decrease
> COLO network performance but seams better than drop lots of pkg.
>
> Thanks
> Zhang Chen
>
Hello, Zhang
Got it.
What is the concern of the massive "drop packets"?
Does the behavior make the COLO do checkpoint periodically (~20 seconds)
instead of doing immediate checkpoint when encountering different
response packets?
It seems that frequent checkpoints caused by the full queue (busy
network) instead of different
response packets may harm the high speed network (10 Gbps or higher)
performance dramatically.
Thanks
Derek
> >
> > Signed-off-by: Derek Su
> > ---
> > net/colo-compare.c | 23 +++
> > 1 file changed, 15 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > 7ee17f2cf8..cdd87b2aa8 100644
> > --- a/net/colo-compare.c
> > +++ b/net/colo-compare.c
> > @@ -120,6 +120,10 @@ enum {
> > SECONDARY_IN,
> > };
> >
> > +static const char *colo_mode[] = {
> > +[PRIMARY_IN] = "primary",
> > +[SECONDARY_IN] = "secondary",
> > +};
> >
> > static int compare_chr_send(CompareState *s,
> > const uint8_t *buf, @@ -215,6 +219,7 @@ static
> > int
> > packet_enqueue(CompareState *s, int mode, Connection **con)
> > ConnectionKey key;
> > Packet *pkt = NULL;
> > Connection *conn;
> > +int ret;
> >
> > if (mode == PRIMARY_IN) {
> > pkt = packet_new(s->pri_rs.buf, @@ -243,16 +248,18 @@ static int
> > packet_enqueue(CompareState *s, int mode, Connection **con)
> > }
> >
> > if (mode == PRIMARY_IN) {
> > -if (!colo_insert_packet(>primary_list, pkt, >pack)) {
> > -error_report("colo compare primary queue size too big,"
> > - "drop packet");
> > -}
> > +ret = colo_insert_packet(>primary_list, pkt,
> > + >pack);
> > } else {
> > -if (!colo_insert_packet(>secondary_list, pkt, >sack)) {
> > -error_report("colo compare secondary queue size too big,"
> > - "drop packet");
> > -}
> > +ret = colo_insert_packet(>secondary_list, pkt,
> > + >sack);
> > }
> > +
> > +if (!ret) {
> > +error_report("colo compare %s queue size too big,"
> > + "drop packet", colo_mode[mode]);
> > +packet_destroy(pkt, NULL);
> > +pkt = NULL;
> > +}
> > +
> > *con = conn;
> >
> > return 0;
> > --
> > 2.17.1
>
RE: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in packet_enqueue()
> -Original Message-
> From: Derek Su
> Sent: Monday, March 23, 2020 1:48 AM
> To: qemu-devel@nongnu.org
> Cc: Zhang, Chen ; lizhij...@cn.fujitsu.com;
> jasow...@redhat.com; dere...@qnap.com
> Subject: [PATCH v2 1/1] net/colo-compare.c: Fix memory leak in
> packet_enqueue()
>
> The patch is to fix the "pkt" memory leak in packet_enqueue().
> The allocated "pkt" needs to be freed if the colo compare primary or
> secondary queue is too big.
Hi Derek,
Thank you for the patch.
I re-think this issue in a big view, looks just free the pkg is not enough in
this situation.
The root cause is network is too busy to compare, So, better choice is notify
COLO frame
to do a checkpoint and clean up all the network queue. This work maybe decrease
COLO network performance but seams better than drop lots of pkg.
Thanks
Zhang Chen
>
> Signed-off-by: Derek Su
> ---
> net/colo-compare.c | 23 +++
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/net/colo-compare.c b/net/colo-compare.c index
> 7ee17f2cf8..cdd87b2aa8 100644
> --- a/net/colo-compare.c
> +++ b/net/colo-compare.c
> @@ -120,6 +120,10 @@ enum {
> SECONDARY_IN,
> };
>
> +static const char *colo_mode[] = {
> +[PRIMARY_IN] = "primary",
> +[SECONDARY_IN] = "secondary",
> +};
>
> static int compare_chr_send(CompareState *s,
> const uint8_t *buf, @@ -215,6 +219,7 @@ static
> int
> packet_enqueue(CompareState *s, int mode, Connection **con)
> ConnectionKey key;
> Packet *pkt = NULL;
> Connection *conn;
> +int ret;
>
> if (mode == PRIMARY_IN) {
> pkt = packet_new(s->pri_rs.buf, @@ -243,16 +248,18 @@ static int
> packet_enqueue(CompareState *s, int mode, Connection **con)
> }
>
> if (mode == PRIMARY_IN) {
> -if (!colo_insert_packet(>primary_list, pkt, >pack)) {
> -error_report("colo compare primary queue size too big,"
> - "drop packet");
> -}
> +ret = colo_insert_packet(>primary_list, pkt,
> + >pack);
> } else {
> -if (!colo_insert_packet(>secondary_list, pkt, >sack)) {
> -error_report("colo compare secondary queue size too big,"
> - "drop packet");
> -}
> +ret = colo_insert_packet(>secondary_list, pkt,
> + >sack);
> }
> +
> +if (!ret) {
> +error_report("colo compare %s queue size too big,"
> + "drop packet", colo_mode[mode]);
> +packet_destroy(pkt, NULL);
> +pkt = NULL;
> +}
> +
> *con = conn;
>
> return 0;
> --
> 2.17.1
