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References: <20211008235830.127167-1-ferruh.yigit@intel.com>
In-Reply-To: <20211008235830.127167-1-ferruh.yigit@intel.com>
From: Igor Ryzhov <iryzhov@nfware.com>
Date: Wed, 17 Nov 2021 19:42:40 +0300
Message-ID: <CAF+s_Fx7U8njih7+WW=8AVG+riuyLggQHy0V93bg3HK+x_9ZCw@mail.gmail.com>
Subject: Re: [PATCH] kni: restrict bifurcated device support
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: Elad Nachman <eladv6@gmail.com>, dev@dpdk.org, stable@dpdk.org,
Eric Christian <erclists@gmail.com>,
Stephen Hemminger <stephen@networkplumber.org>
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--00000000000097a04d05d0febbb0
Content-Type: text/plain; charset="UTF-8"
Acked-by: Igor Ryzhov <iryzhov@nfware.com>
On Sat, Oct 9, 2021 at 2:58 AM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> To enable bifurcated device support, rtnl_lock is released before calling
> userspace callbacks and asynchronous requests are enabled.
>
> But these changes caused more issues, like bug #809, #816. To reduce the
> scope of the problems, the bifurcated device support related changes are
> only enabled when it is requested explicitly with new 'enable_bifurcated'
> module parameter.
> And bifurcated device support is disabled by default.
>
> So the bifurcated device related problems are isolated and they can be
> fixed without impacting all use cases.
>
> Bugzilla ID: 816
> Fixes: 631217c76135 ("kni: fix kernel deadlock with bifurcated device")
> Cc: stable@dpdk.org
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> ---
> Cc: Igor Ryzhov <iryzhov@nfware.com>
> Cc: Elad Nachman <eladv6@gmail.com>
> Cc: Eric Christian <erclists@gmail.com>
> Cc: Stephen Hemminger <stephen@networkplumber.org>
> ---
> .../prog_guide/kernel_nic_interface.rst | 28 +++++++++++++
> kernel/linux/kni/kni_dev.h | 3 ++
> kernel/linux/kni/kni_misc.c | 36 ++++++++++++++++
> kernel/linux/kni/kni_net.c | 42 +++++++++++--------
> 4 files changed, 92 insertions(+), 17 deletions(-)
>
> diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst
> b/doc/guides/prog_guide/kernel_nic_interface.rst
> index 1ce03ec1a374..771c7d7fdac4 100644
> --- a/doc/guides/prog_guide/kernel_nic_interface.rst
> +++ b/doc/guides/prog_guide/kernel_nic_interface.rst
> @@ -56,6 +56,12 @@ can be specified when the module is loaded to control
> its behavior:
> off Interfaces will be created with carrier state
> set to off.
> on Interfaces will be created with carrier state
> set to on.
> (charp)
> + parm: enable_bifurcated: Enable request processing support
> for
> + bifurcated drivers, which means releasing rtnl_lock
> before calling
> + userspace callback and supporting async requests
> (default=off):
> + on Enable request processing support for
> bifurcated drivers.
> + (charp)
> +
>
> Loading the ``rte_kni`` kernel module without any optional parameters is
> the typical way a DPDK application gets packets into and out of the kernel
> @@ -174,6 +180,28 @@ To set the default carrier state to *off*:
> If the ``carrier`` parameter is not specified, the default carrier state
> of KNI interfaces will be set to *off*.
>
> +.. _kni_bifurcated_device_support:
> +
> +Bifurcated Device Support
> +~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +User callbacks are executed while kernel module holds the ``rtnl`` lock,
> this
> +causes a deadlock when callbacks run control commands on another Linux
> kernel
> +network interface.
> +
> +Bifurcated devices has kernel network driver part and to prevent deadlock
> for
> +them ``enable_bifurcated`` is used.
> +
> +To enable bifurcated device support:
> +
> +.. code-block:: console
> +
> + # insmod <build_dir>/kernel/linux/kni/rte_kni.ko enable_bifurcated=on
> +
> +Enabling bifurcated device support releases ``rtnl`` lock before calling
> +callback and locks it back after callback. Also enables asynchronous
> request to
> +support callbacks that requires rtnl lock to work (interface down).
> +
> KNI Creation and Deletion
> -------------------------
>
> diff --git a/kernel/linux/kni/kni_dev.h b/kernel/linux/kni/kni_dev.h
> index c15da311ba25..e8633486eeb8 100644
> --- a/kernel/linux/kni/kni_dev.h
> +++ b/kernel/linux/kni/kni_dev.h
> @@ -34,6 +34,9 @@
> /* Default carrier state for created KNI network interfaces */
> extern uint32_t kni_dflt_carrier;
>
> +/* Request processing support for bifurcated drivers. */
> +extern uint32_t bifurcated_support;
> +
> /**
> * A structure describing the private information for a kni device.
> */
> diff --git a/kernel/linux/kni/kni_misc.c b/kernel/linux/kni/kni_misc.c
> index 2b464c438113..aae977c187a9 100644
> --- a/kernel/linux/kni/kni_misc.c
> +++ b/kernel/linux/kni/kni_misc.c
> @@ -41,6 +41,10 @@ static uint32_t multiple_kthread_on;
> static char *carrier;
> uint32_t kni_dflt_carrier;
>
> +/* Request processing support for bifurcated drivers. */
> +static char *enable_bifurcated;
> +uint32_t bifurcated_support;
> +
> #define KNI_DEV_IN_USE_BIT_NUM 0 /* Bit number for device in use */
>
> static int kni_net_id;
> @@ -568,6 +572,22 @@ kni_parse_carrier_state(void)
> return 0;
> }
>
> +static int __init
> +kni_parse_bifurcated_support(void)
> +{
> + if (!enable_bifurcated) {
> + bifurcated_support = 0;
> + return 0;
> + }
> +
> + if (strcmp(enable_bifurcated, "on") == 0)
> + bifurcated_support = 1;
> + else
> + return -1;
> +
> + return 0;
> +}
> +
> static int __init
> kni_init(void)
> {
> @@ -593,6 +613,13 @@ kni_init(void)
> else
> pr_debug("Default carrier state set to on.\n");
>
> + if (kni_parse_bifurcated_support() < 0) {
> + pr_err("Invalid parameter for bifurcated support\n");
> + return -EINVAL;
> + }
> + if (bifurcated_support == 1)
> + pr_debug("bifurcated support is enabled.\n");
> +
> #ifdef HAVE_SIMPLIFIED_PERNET_OPERATIONS
> rc = register_pernet_subsys(&kni_net_ops);
> #else
> @@ -659,3 +686,12 @@ MODULE_PARM_DESC(carrier,
> "\t\ton Interfaces will be created with carrier state set to on.\n"
> "\t\t"
> );
> +
> +module_param(enable_bifurcated, charp, 0644);
> +MODULE_PARM_DESC(enable_bifurcated,
> +"Enable request processing support for bifurcated drivers, "
> +"which means releasing rtnl_lock before calling userspace callback and "
> +"supporting async requests (default=off):\n"
> +"\t\ton Enable request processing support for bifurcated drivers.\n"
> +"\t\t"
> +);
> diff --git a/kernel/linux/kni/kni_net.c b/kernel/linux/kni/kni_net.c
> index 611719b5ee27..29e5b9e21f9e 100644
> --- a/kernel/linux/kni/kni_net.c
> +++ b/kernel/linux/kni/kni_net.c
> @@ -113,12 +113,14 @@ kni_net_process_request(struct net_device *dev,
> struct rte_kni_request *req)
>
> ASSERT_RTNL();
>
> - /* If we need to wait and RTNL mutex is held
> - * drop the mutex and hold reference to keep device
> - */
> - if (req->async == 0) {
> - dev_hold(dev);
> - rtnl_unlock();
> + if (bifurcated_support) {
> + /* If we need to wait and RTNL mutex is held
> + * drop the mutex and hold reference to keep device
> + */
> + if (req->async == 0) {
> + dev_hold(dev);
> + rtnl_unlock();
> + }
> }
>
> mutex_lock(&kni->sync_lock);
> @@ -132,12 +134,14 @@ kni_net_process_request(struct net_device *dev,
> struct rte_kni_request *req)
> goto fail;
> }
>
> - /* No result available since request is handled
> - * asynchronously. set response to success.
> - */
> - if (req->async != 0) {
> - req->result = 0;
> - goto async;
> + if (bifurcated_support) {
> + /* No result available since request is handled
> + * asynchronously. set response to success.
> + */
> + if (req->async != 0) {
> + req->result = 0;
> + goto async;
> + }
> }
>
> ret_val = wait_event_interruptible_timeout(kni->wq,
> @@ -160,9 +164,11 @@ kni_net_process_request(struct net_device *dev,
> struct rte_kni_request *req)
>
> fail:
> mutex_unlock(&kni->sync_lock);
> - if (req->async == 0) {
> - rtnl_lock();
> - dev_put(dev);
> + if (bifurcated_support) {
> + if (req->async == 0) {
> + rtnl_lock();
> + dev_put(dev);
> + }
> }
> return ret;
> }
> @@ -207,8 +213,10 @@ kni_net_release(struct net_device *dev)
> /* Setting if_up to 0 means down */
> req.if_up = 0;
>
> - /* request async because of the deadlock problem */
> - req.async = 1;
> + if (bifurcated_support) {
> + /* request async because of the deadlock problem */
> + req.async = 1;
> + }
>
> ret = kni_net_process_request(dev, &req);
>
> --
> 2.31.1
>
>
--00000000000097a04d05d0febbb0
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr">Acked-by: Igor Ryzhov <<a href=3D"mailto:iryzhov@nfware=
.com">iryzhov@nfware.com</a>></div><br><div class=3D"gmail_quote"><div d=
ir=3D"ltr" class=3D"gmail_attr">On Sat, Oct 9, 2021 at 2:58 AM Ferruh Yigit=
<<a href=3D"mailto:ferruh.yigit@intel.com">ferruh.yigit@intel.com</a>&g=
t; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0p=
x 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color=
:rgb(204,204,204);padding-left:1ex">To enable bifurcated device support, rt=
nl_lock is released before calling<br>
userspace callbacks and asynchronous requests are enabled.<br>
<br>
But these changes caused more issues, like bug #809, #816. To reduce the<br=
>
scope of the problems, the bifurcated device support related changes are<br=
>
only enabled when it is requested explicitly with new 'enable_bifurcate=
d'<br>
module parameter.<br>
And bifurcated device support is disabled by default.<br>
<br>
So the bifurcated device related problems are isolated and they can be<br>
fixed without impacting all use cases.<br>
<br>
Bugzilla ID: 816<br>
Fixes: 631217c76135 ("kni: fix kernel deadlock with bifurcated device&=
quot;)<br>
Cc: <a href=3D"mailto:stable@dpdk.org" target=3D"_blank">stable@dpdk.org</a=
><br>
<br>
Signed-off-by: Ferruh Yigit <<a href=3D"mailto:ferruh.yigit@intel.com" t=
arget=3D"_blank">ferruh.yigit@intel.com</a>><br>
---<br>
Cc: Igor Ryzhov <<a href=3D"mailto:iryzhov@nfware.com" target=3D"_blank"=
>iryzhov@nfware.com</a>><br>
Cc: Elad Nachman <<a href=3D"mailto:eladv6@gmail.com" target=3D"_blank">=
eladv6@gmail.com</a>><br>
Cc: Eric Christian <<a href=3D"mailto:erclists@gmail.com" target=3D"_bla=
nk">erclists@gmail.com</a>><br>
Cc: Stephen Hemminger <<a href=3D"mailto:stephen@networkplumber.org" tar=
get=3D"_blank">stephen@networkplumber.org</a>><br>
---<br>
=C2=A0.../prog_guide/kernel_nic_interface.rst=C2=A0 =C2=A0 =C2=A0 =C2=A0| 2=
8 +++++++++++++<br>
=C2=A0kernel/linux/kni/kni_dev.h=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 |=C2=A0 3 ++<br>
=C2=A0kernel/linux/kni/kni_misc.c=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0| 36 ++++++++++++++++<br>
=C2=A0kernel/linux/kni/kni_net.c=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 | 42 +++++++++++--------<br>
=C2=A04 files changed, 92 insertions(+), 17 deletions(-)<br>
<br>
diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/pr=
og_guide/kernel_nic_interface.rst<br>
index 1ce03ec1a374..771c7d7fdac4 100644<br>
--- a/doc/guides/prog_guide/kernel_nic_interface.rst<br>
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst<br>
@@ -56,6 +56,12 @@ can be specified when the module is loaded to control it=
s behavior:<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0off=C2=A0 =C2=A0Interfaces will be created with carrier state set to off=
.<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0on=C2=A0 =C2=A0 Interfaces will be created with carrier state set to on.=
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 (charp)<br>
+=C2=A0 =C2=A0 parm:=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0enable_bifurca=
ted: Enable request processing support for<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 bifu=
rcated drivers, which means releasing rtnl_lock before calling<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 user=
space callback and supporting async requests (default=3Doff):<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 on=
=C2=A0 =C2=A0 Enable request processing support for bifurcated drivers.<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0(charp)<br>
+<br>
<br>
=C2=A0Loading the ``rte_kni`` kernel module without any optional parameters=
is<br>
=C2=A0the typical way a DPDK application gets packets into and out of the k=
ernel<br>
@@ -174,6 +180,28 @@ To set the default carrier state to *off*:<br>
=C2=A0If the ``carrier`` parameter is not specified, the default carrier st=
ate<br>
=C2=A0of KNI interfaces will be set to *off*.<br>
<br>
+.. _kni_bifurcated_device_support:<br>
+<br>
+Bifurcated Device Support<br>
+~~~~~~~~~~~~~~~~~~~~~~~~~<br>
+<br>
+User callbacks are executed while kernel module holds the ``rtnl`` lock, t=
his<br>
+causes a deadlock when callbacks run control commands on another Linux ker=
nel<br>
+network interface.<br>
+<br>
+Bifurcated devices has kernel network driver part and to prevent deadlock =
for<br>
+them ``enable_bifurcated`` is used.<br>
+<br>
+To enable bifurcated device support:<br>
+<br>
+.. code-block:: console<br>
+<br>
+=C2=A0 =C2=A0 # insmod <build_dir>/kernel/linux/kni/rte_kni.ko enabl=
e_bifurcated=3Don<br>
+<br>
+Enabling bifurcated device support releases ``rtnl`` lock before calling<b=
r>
+callback and locks it back after callback. Also enables asynchronous reque=
st to<br>
+support callbacks that requires rtnl lock to work (interface down).<br>
+<br>
=C2=A0KNI Creation and Deletion<br>
=C2=A0-------------------------<br>
<br>
diff --git a/kernel/linux/kni/kni_dev.h b/kernel/linux/kni/kni_dev.h<br>
index c15da311ba25..e8633486eeb8 100644<br>
--- a/kernel/linux/kni/kni_dev.h<br>
+++ b/kernel/linux/kni/kni_dev.h<br>
@@ -34,6 +34,9 @@<br>
=C2=A0/* Default carrier state for created KNI network interfaces */<br>
=C2=A0extern uint32_t kni_dflt_carrier;<br>
<br>
+/* Request processing support for bifurcated drivers. */<br>
+extern uint32_t bifurcated_support;<br>
+<br>
=C2=A0/**<br>
=C2=A0 * A structure describing the private information for a kni device.<b=
r>
=C2=A0 */<br>
diff --git a/kernel/linux/kni/kni_misc.c b/kernel/linux/kni/kni_misc.c<br>
index 2b464c438113..aae977c187a9 100644<br>
--- a/kernel/linux/kni/kni_misc.c<br>
+++ b/kernel/linux/kni/kni_misc.c<br>
@@ -41,6 +41,10 @@ static uint32_t multiple_kthread_on;<br>
=C2=A0static char *carrier;<br>
=C2=A0uint32_t kni_dflt_carrier;<br>
<br>
+/* Request processing support for bifurcated drivers. */<br>
+static char *enable_bifurcated;<br>
+uint32_t bifurcated_support;<br>
+<br>
=C2=A0#define KNI_DEV_IN_USE_BIT_NUM 0 /* Bit number for device in use */<b=
r>
<br>
=C2=A0static int kni_net_id;<br>
@@ -568,6 +572,22 @@ kni_parse_carrier_state(void)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 return 0;<br>
=C2=A0}<br>
<br>
+static int __init<br>
+kni_parse_bifurcated_support(void)<br>
+{<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (!enable_bifurcated) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0bifurcated_support =
=3D 0;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return 0;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
+<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (strcmp(enable_bifurcated, "on") =
=3D=3D 0)<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0bifurcated_support =
=3D 1;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0else<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return -1;<br>
+<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0return 0;<br>
+}<br>
+<br>
=C2=A0static int __init<br>
=C2=A0kni_init(void)<br>
=C2=A0{<br>
@@ -593,6 +613,13 @@ kni_init(void)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 else<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 pr_debug("Defa=
ult carrier state set to on.\n");<br>
<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (kni_parse_bifurcated_support() < 0) {<br=
>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0pr_err("Invali=
d parameter for bifurcated support\n");<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return -EINVAL;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (bifurcated_support =3D=3D 1)<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0pr_debug("bifu=
rcated support is enabled.\n");<br>
+<br>
=C2=A0#ifdef HAVE_SIMPLIFIED_PERNET_OPERATIONS<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 rc =3D register_pernet_subsys(&kni_net_ops)=
;<br>
=C2=A0#else<br>
@@ -659,3 +686,12 @@ MODULE_PARM_DESC(carrier,<br>
=C2=A0"\t\ton=C2=A0 =C2=A0 Interfaces will be created with carrier sta=
te set to on.\n"<br>
=C2=A0"\t\t"<br>
=C2=A0);<br>
+<br>
+module_param(enable_bifurcated, charp, 0644);<br>
+MODULE_PARM_DESC(enable_bifurcated,<br>
+"Enable request processing support for bifurcated drivers, "<br>
+"which means releasing rtnl_lock before calling userspace callback an=
d "<br>
+"supporting async requests (default=3Doff):\n"<br>
+"\t\ton=C2=A0 =C2=A0 Enable request processing support for bifurcated=
drivers.\n"<br>
+"\t\t"<br>
+);<br>
diff --git a/kernel/linux/kni/kni_net.c b/kernel/linux/kni/kni_net.c<br>
index 611719b5ee27..29e5b9e21f9e 100644<br>
--- a/kernel/linux/kni/kni_net.c<br>
+++ b/kernel/linux/kni/kni_net.c<br>
@@ -113,12 +113,14 @@ kni_net_process_request(struct net_device *dev, struc=
t rte_kni_request *req)<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 ASSERT_RTNL();<br>
<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0/* If we need to wait and RTNL mutex is held<br=
>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 * drop the mutex and hold reference to keep de=
vice<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 */<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async =3D=3D 0) {<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0dev_hold(dev);<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0rtnl_unlock();<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (bifurcated_support) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0/* If we need to wa=
it and RTNL mutex is held<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 * drop the mutex a=
nd hold reference to keep device<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 */<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async =
=3D=3D 0) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0dev_hold(dev);<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0rtnl_unlock();<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 mutex_lock(&kni->sync_lock);<br>
@@ -132,12 +134,14 @@ kni_net_process_request(struct net_device *dev, struc=
t rte_kni_request *req)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 goto fail;<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }<br>
<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0/* No result available since request is handled=
<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 * asynchronously. set response to success.<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 */<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async !=3D 0) {<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0req->result =3D =
0;<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0goto async;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (bifurcated_support) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0/* No result availa=
ble since request is handled<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 * asynchronously. =
set response to success.<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 */<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async !=
=3D 0) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0req->result =3D 0;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0goto async;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 ret_val =3D wait_event_interruptible_timeout(kn=
i->wq,<br>
@@ -160,9 +164,11 @@ kni_net_process_request(struct net_device *dev, struct=
rte_kni_request *req)<br>
<br>
=C2=A0fail:<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 mutex_unlock(&kni->sync_lock);<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async =3D=3D 0) {<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0rtnl_lock();<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0dev_put(dev);<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (bifurcated_support) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (req->async =
=3D=3D 0) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0rtnl_lock();<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0dev_put(dev);<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 return ret;<br>
=C2=A0}<br>
@@ -207,8 +213,10 @@ kni_net_release(struct net_device *dev)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 /* Setting if_up to 0 means down */<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 req.if_up =3D 0;<br>
<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0/* request async because of the deadlock proble=
m */<br>
-=C2=A0 =C2=A0 =C2=A0 =C2=A0req.async =3D 1;<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0if (bifurcated_support) {<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0/* request async be=
cause of the deadlock problem */<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0req.async =3D 1;<br=
>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0}<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 ret =3D kni_net_process_request(dev, &req);=
<br>
<br>
-- <br>
2.31.1<br>
<br>
</blockquote></div>
--00000000000097a04d05d0febbb0--