Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
This will lead to deadlock if calling the function multiple times in
an atomic operation, for example, getting imultiple MST ports status
for a DP MST bonding scenario.
Signed-off-by: Ramya SR <[email protected]>
---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index ed96cfc..d6512c4 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
ret = drm_modeset_lock(&mgr->base.lock, ctx);
if (ret)
- goto out;
+ goto fail;
ret = connector_status_disconnected;
@@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
break;
}
out:
+ drm_modeset_unlock(&mgr->base.lock);
+fail:
drm_dp_mst_topology_put_port(port);
return ret;
}
--
2.7.4
Gentle Reminder. Please review the commit.
-----Original Message-----
From: Ramya SR (QUIC) <[email protected]>
Sent: Friday, September 15, 2023 10:25 AM
To: David Airlie <[email protected]>; Daniel Vetter <[email protected]>; Lyude Paul <[email protected]>; Wayne Lin <[email protected]>; Jani Nikula <[email protected]>; Imre Deak <[email protected]>; Alex Deucher <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]
Cc: Ramya SR (QUIC) <[email protected]>
Subject: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
This will lead to deadlock if calling the function multiple times in an atomic operation, for example, getting imultiple MST ports status for a DP MST bonding scenario.
Signed-off-by: Ramya SR <[email protected]>
---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index ed96cfc..d6512c4 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
ret = drm_modeset_lock(&mgr->base.lock, ctx);
if (ret)
- goto out;
+ goto fail;
ret = connector_status_disconnected;
@@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
break;
}
out:
+ drm_modeset_unlock(&mgr->base.lock);
+fail:
drm_dp_mst_topology_put_port(port);
return ret;
}
--
2.7.4
Oh! wow thank you for catching this:
Reviewed-by: Lyude Paul <[email protected]>
I will go and push this to drm-misc-next in just a moment
On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> This will lead to deadlock if calling the function multiple times in
> an atomic operation, for example, getting imultiple MST ports status
> for a DP MST bonding scenario.
>
> Signed-off-by: Ramya SR <[email protected]>
> ---
> drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> index ed96cfc..d6512c4 100644
> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
>
> ret = drm_modeset_lock(&mgr->base.lock, ctx);
> if (ret)
> - goto out;
> + goto fail;
>
> ret = connector_status_disconnected;
>
> @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> break;
> }
> out:
> + drm_modeset_unlock(&mgr->base.lock);
> +fail:
> drm_dp_mst_topology_put_port(port);
> return ret;
> }
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
…ugh, thanks for catching that :|
yes you're completely right - NAK on this patch then
On Fri, 2023-09-22 at 22:22 +0300, Imre Deak wrote:
> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
> >
> > Oh! wow thank you for catching this:
> >
> > Reviewed-by: Lyude Paul <[email protected]>
> >
> > I will go and push this to drm-misc-next in just a moment
> >
> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > > This will lead to deadlock if calling the function multiple times in
> > > an atomic operation, for example, getting imultiple MST ports status
> > > for a DP MST bonding scenario.
> > >
> > > Signed-off-by: Ramya SR <[email protected]>
> > > ---
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index ed96cfc..d6512c4 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > >
> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > > if (ret)
> > > - goto out;
> > > + goto fail;
> > >
> > > ret = connector_status_disconnected;
> > >
> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > > break;
> > > }
> > > out:
> > > + drm_modeset_unlock(&mgr->base.lock);
>
> Isn't this supposed to be unlocked only by drm_helper_probe_detect_ctx()
> / drm_helper_probe_detect() ?
>
> > > +fail:
> > > drm_dp_mst_topology_put_port(port);
> > > return ret;
> > > }
> >
> > --
> > Cheers,
> > Lyude Paul (she/her)
> > Software Engineer at Red Hat
> >
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
>
> Oh! wow thank you for catching this:
>
> Reviewed-by: Lyude Paul <[email protected]>
>
> I will go and push this to drm-misc-next in just a moment
>
> On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > This will lead to deadlock if calling the function multiple times in
> > an atomic operation, for example, getting imultiple MST ports status
> > for a DP MST bonding scenario.
> >
> > Signed-off-by: Ramya SR <[email protected]>
> > ---
> > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > index ed96cfc..d6512c4 100644
> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> >
> > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > if (ret)
> > - goto out;
> > + goto fail;
> >
> > ret = connector_status_disconnected;
> >
> > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > break;
> > }
> > out:
> > + drm_modeset_unlock(&mgr->base.lock);
Isn't this supposed to be unlocked only by drm_helper_probe_detect_ctx()
/ drm_helper_probe_detect() ?
> > +fail:
> > drm_dp_mst_topology_put_port(port);
> > return ret;
> > }
>
> --
> Cheers,
> Lyude Paul (she/her)
> Software Engineer at Red Hat
>
On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>
> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
> >
> > Oh! wow thank you for catching this:
> >
> > Reviewed-by: Lyude Paul <[email protected]>
> >
> > I will go and push this to drm-misc-next in just a moment
> >
> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > > This will lead to deadlock if calling the function multiple times in
> > > an atomic operation, for example, getting imultiple MST ports status
> > > for a DP MST bonding scenario.
> > >
> > > Signed-off-by: Ramya SR <[email protected]>
> > > ---
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index ed96cfc..d6512c4 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > >
> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > > if (ret)
> > > - goto out;
> > > + goto fail;
> > >
> > > ret = connector_status_disconnected;
> > >
> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > > break;
> > > }
> > > out:
> > > + drm_modeset_unlock(&mgr->base.lock);
>
> Isn't this supposed to be unlocked only by drm_helper_probe_detect_ctx()
> / drm_helper_probe_detect() ?
Maybe adding a comment to that effect would be helpful for the future.
Alex
>
> > > +fail:
> > > drm_dp_mst_topology_put_port(port);
> > > return ret;
> > > }
> >
> > --
> > Cheers,
> > Lyude Paul (she/her)
> > Software Engineer at Red Hat
> >
-----Original Message-----
From: Alex Deucher <[email protected]>
Sent: Monday, September 25, 2023 8:27 PM
To: [email protected]
Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: Re: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>
> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
> >
> > Oh! wow thank you for catching this:
> >
> > Reviewed-by: Lyude Paul <[email protected]>
> >
> > I will go and push this to drm-misc-next in just a moment
> >
> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > > This will lead to deadlock if calling the function multiple times
> > > in an atomic operation, for example, getting imultiple MST ports
> > > status for a DP MST bonding scenario.
> > >
> > > Signed-off-by: Ramya SR <[email protected]>
> > > ---
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index ed96cfc..d6512c4 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector
> > > *connector,
> > >
> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > > if (ret)
> > > - goto out;
> > > + goto fail;
> > >
> > > ret = connector_status_disconnected;
> > >
> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > > break;
> > > }
> > > out:
> > > + drm_modeset_unlock(&mgr->base.lock);
>
> Isn't this supposed to be unlocked only by
> drm_helper_probe_detect_ctx() / drm_helper_probe_detect() ?
Maybe adding a comment to that effect would be helpful for the future.
Alex
>this is different lock, above function mentioned is locking/unlocking the global connection_mutex, that is required always locked during the atomic >check/commit. Here we are talking about MST topology manager mutex "mgr->base.lock".
>For normal non-bond MST, it's ok, the calling sequence for detecting MST connector status is
> dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is locked)
> Then for the bond MST case, to figure out if the sibling connectors are also connected, so that the bonding is possible, we need detect two or more connectors >in single dp_mst_connector_detect call
>dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is locked)
>dp_mst_find_sibling_connector ->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port ->drm_dp_mst_detect_port (blocked by mgr->base.lock)
>
> > > +fail:
> > > drm_dp_mst_topology_put_port(port);
> > > return ret;
> > > }
> >
> > --
> > Cheers,
> > Lyude Paul (she/her)
> > Software Engineer at Red Hat
> >
Reminder. Please review the reply comment.
Thanks and Regards,
Ramya SR
-----Original Message-----
From: Ramya SR
Sent: Tuesday, September 26, 2023 4:12 PM
To: Alex Deucher <[email protected]>; [email protected]
Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
-----Original Message-----
From: Alex Deucher <[email protected]>
Sent: Monday, September 25, 2023 8:27 PM
To: [email protected]
Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: Re: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>
> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
> >
> > Oh! wow thank you for catching this:
> >
> > Reviewed-by: Lyude Paul <[email protected]>
> >
> > I will go and push this to drm-misc-next in just a moment
> >
> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > > This will lead to deadlock if calling the function multiple times
> > > in an atomic operation, for example, getting imultiple MST ports
> > > status for a DP MST bonding scenario.
> > >
> > > Signed-off-by: Ramya SR <[email protected]>
> > > ---
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index ed96cfc..d6512c4 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector
> > > *connector,
> > >
> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > > if (ret)
> > > - goto out;
> > > + goto fail;
> > >
> > > ret = connector_status_disconnected;
> > >
> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > > break;
> > > }
> > > out:
> > > + drm_modeset_unlock(&mgr->base.lock);
>
> Isn't this supposed to be unlocked only by
> drm_helper_probe_detect_ctx() / drm_helper_probe_detect() ?
Maybe adding a comment to that effect would be helpful for the future.
Alex
>this is different lock, above function mentioned is locking/unlocking the global connection_mutex, that is required always locked during the atomic >check/commit. Here we are talking about MST topology manager mutex "mgr->base.lock".
>For normal non-bond MST, it's ok, the calling sequence for detecting
>MST connector status is dp_mst_connector_detect
>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>->drm_dp_mst_detect_port (where mgr->base.lock is locked)
> Then for the bond MST case, to figure out if the sibling connectors
> are also connected, so that the bonding is possible, we need detect
> two or more connectors >in single dp_mst_connector_detect call
>dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx =
>dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is
>locked) dp_mst_find_sibling_connector
>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>->drm_dp_mst_detect_port (blocked by mgr->base.lock)
>
> > > +fail:
> > > drm_dp_mst_topology_put_port(port);
> > > return ret;
> > > }
> >
> > --
> > Cheers,
> > Lyude Paul (she/her)
> > Software Engineer at Red Hat
> >
On Thu, 28 Sep 2023, Ramya SR <[email protected]> wrote:
> Reminder. Please review the reply comment.
Maybe send a patch to review?
It's also not helping that your previous mail looks like it's just
quoting other messages [1].
BR,
Jani.
[1] https://lore.kernel.org/all/BN0PR02MB79517B267D593DC484BA34DF81C3A@BN0PR02MB7951.namprd02.prod.outlook.com/
>
> Thanks and Regards,
> Ramya SR
>
> -----Original Message-----
> From: Ramya SR
> Sent: Tuesday, September 26, 2023 4:12 PM
> To: Alex Deucher <[email protected]>; [email protected]
> Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
> Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
>
>
>
> -----Original Message-----
> From: Alex Deucher <[email protected]>
> Sent: Monday, September 25, 2023 8:27 PM
> To: [email protected]
> Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
> Subject: Re: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
>
> WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
>
> On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>>
>> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
>> >
>> > Oh! wow thank you for catching this:
>> >
>> > Reviewed-by: Lyude Paul <[email protected]>
>> >
>> > I will go and push this to drm-misc-next in just a moment
>> >
>> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
>> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
>> > > This will lead to deadlock if calling the function multiple times
>> > > in an atomic operation, for example, getting imultiple MST ports
>> > > status for a DP MST bonding scenario.
>> > >
>> > > Signed-off-by: Ramya SR <[email protected]>
>> > > ---
>> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
>> > > 1 file changed, 3 insertions(+), 1 deletion(-)
>> > >
>> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > index ed96cfc..d6512c4 100644
>> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector
>> > > *connector,
>> > >
>> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
>> > > if (ret)
>> > > - goto out;
>> > > + goto fail;
>> > >
>> > > ret = connector_status_disconnected;
>> > >
>> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
>> > > break;
>> > > }
>> > > out:
>> > > + drm_modeset_unlock(&mgr->base.lock);
>>
>> Isn't this supposed to be unlocked only by
>> drm_helper_probe_detect_ctx() / drm_helper_probe_detect() ?
>
> Maybe adding a comment to that effect would be helpful for the future.
>
> Alex
>
>>this is different lock, above function mentioned is locking/unlocking the global connection_mutex, that is required always locked during the atomic >check/commit. Here we are talking about MST topology manager mutex "mgr->base.lock".
>
>>For normal non-bond MST, it's ok, the calling sequence for detecting
>>MST connector status is dp_mst_connector_detect
>>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>>->drm_dp_mst_detect_port (where mgr->base.lock is locked)
>
>> Then for the bond MST case, to figure out if the sibling connectors
>> are also connected, so that the bonding is possible, we need detect
>> two or more connectors >in single dp_mst_connector_detect call
>
>>dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx =
>>dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is
>>locked) dp_mst_find_sibling_connector
>>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>>->drm_dp_mst_detect_port (blocked by mgr->base.lock)
>
>>
>> > > +fail:
>> > > drm_dp_mst_topology_put_port(port);
>> > > return ret;
>> > > }
>> >
>> > --
>> > Cheers,
>> > Lyude Paul (she/her)
>> > Software Engineer at Red Hat
>> >
--
Jani Nikula, Intel
Hi All ,
Please review the reply comment.
Regards,
Ramya SR
-----Original Message-----
From: Ramya SR
Sent: Thursday, September 28, 2023 7:55 AM
To: 'Alex Deucher' <[email protected]>; '[email protected]' <[email protected]>
Cc: 'Lyude Paul' <[email protected]>; 'Jani Nikula' <[email protected]>; 'Jeff Layton' <[email protected]>; '[email protected]' <[email protected]>; '[email protected]' <[email protected]>; 'Wayne Lin' <[email protected]>; 'Alex Deucher' <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
Reminder. Please review the reply comment.
Thanks and Regards,
Ramya SR
-----Original Message-----
From: Ramya SR
Sent: Tuesday, September 26, 2023 4:12 PM
To: Alex Deucher <[email protected]>; [email protected]
Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
-----Original Message-----
From: Alex Deucher <[email protected]>
Sent: Monday, September 25, 2023 8:27 PM
To: [email protected]
Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
Subject: Re: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>
> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
> >
> > Oh! wow thank you for catching this:
> >
> > Reviewed-by: Lyude Paul <[email protected]>
> >
> > I will go and push this to drm-misc-next in just a moment
> >
> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
> > > This will lead to deadlock if calling the function multiple times
> > > in an atomic operation, for example, getting imultiple MST ports
> > > status for a DP MST bonding scenario.
> > >
> > > Signed-off-by: Ramya SR <[email protected]>
> > > ---
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index ed96cfc..d6512c4 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector
> > > *connector,
> > >
> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
> > > if (ret)
> > > - goto out;
> > > + goto fail;
> > >
> > > ret = connector_status_disconnected;
> > >
> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
> > > break;
> > > }
> > > out:
> > > + drm_modeset_unlock(&mgr->base.lock);
>
> Isn't this supposed to be unlocked only by
> drm_helper_probe_detect_ctx() / drm_helper_probe_detect() ?
Maybe adding a comment to that effect would be helpful for the future.
Alex
>this is different lock, above function mentioned is locking/unlocking the global connection_mutex, that is required always locked during the atomic >check/commit. Here we are talking about MST topology manager mutex "mgr->base.lock".
>For normal non-bond MST, it's ok, the calling sequence for detecting
>MST connector status is dp_mst_connector_detect
>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>->drm_dp_mst_detect_port (where mgr->base.lock is locked)
> Then for the bond MST case, to figure out if the sibling connectors
> are also connected, so that the bonding is possible, we need detect
> two or more connectors >in single dp_mst_connector_detect call
>dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx =
>dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is
>locked) dp_mst_find_sibling_connector
>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>->drm_dp_mst_detect_port (blocked by mgr->base.lock)
>
> > > +fail:
> > > drm_dp_mst_topology_put_port(port);
> > > return ret;
> > > }
> >
> > --
> > Cheers,
> > Lyude Paul (she/her)
> > Software Engineer at Red Hat
> >
On Fri, 29 Sep 2023, Ramya SR <[email protected]> wrote:
> Hi All ,
>
> Please review the reply comment.
Please read the responses you do get [1]. Please stop
top-posting. Please fix your mail client.
BR,
Jani.
[1] https://lore.kernel.org/r/[email protected]
>
> Regards,
> Ramya SR
>
> -----Original Message-----
> From: Ramya SR
> Sent: Thursday, September 28, 2023 7:55 AM
> To: 'Alex Deucher' <[email protected]>; '[email protected]' <[email protected]>
> Cc: 'Lyude Paul' <[email protected]>; 'Jani Nikula' <[email protected]>; 'Jeff Layton' <[email protected]>; '[email protected]' <[email protected]>; '[email protected]' <[email protected]>; 'Wayne Lin' <[email protected]>; 'Alex Deucher' <[email protected]>; Ramya SR (QUIC) <[email protected]>
> Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
>
> Reminder. Please review the reply comment.
>
> Thanks and Regards,
> Ramya SR
>
> -----Original Message-----
> From: Ramya SR
> Sent: Tuesday, September 26, 2023 4:12 PM
> To: Alex Deucher <[email protected]>; [email protected]
> Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
> Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
>
>
>
> -----Original Message-----
> From: Alex Deucher <[email protected]>
> Sent: Monday, September 25, 2023 8:27 PM
> To: [email protected]
> Cc: Lyude Paul <[email protected]>; Jani Nikula <[email protected]>; Jeff Layton <[email protected]>; [email protected]; [email protected]; Wayne Lin <[email protected]>; Alex Deucher <[email protected]>; Ramya SR (QUIC) <[email protected]>
> Subject: Re: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect
>
> WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
>
> On Fri, Sep 22, 2023 at 3:22 PM Imre Deak <[email protected]> wrote:
>>
>> On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote:
>> >
>> > Oh! wow thank you for catching this:
>> >
>> > Reviewed-by: Lyude Paul <[email protected]>
>> >
>> > I will go and push this to drm-misc-next in just a moment
>> >
>> > On Fri, 2023-09-15 at 10:24 +0530, Ramya SR wrote:
>> > > Modeset mutex unlock is missing in drm_dp_mst_detect_port function.
>> > > This will lead to deadlock if calling the function multiple times
>> > > in an atomic operation, for example, getting imultiple MST ports
>> > > status for a DP MST bonding scenario.
>> > >
>> > > Signed-off-by: Ramya SR <[email protected]>
>> > > ---
>> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
>> > > 1 file changed, 3 insertions(+), 1 deletion(-)
>> > >
>> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > index ed96cfc..d6512c4 100644
>> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>> > > @@ -4154,7 +4154,7 @@ drm_dp_mst_detect_port(struct drm_connector
>> > > *connector,
>> > >
>> > > ret = drm_modeset_lock(&mgr->base.lock, ctx);
>> > > if (ret)
>> > > - goto out;
>> > > + goto fail;
>> > >
>> > > ret = connector_status_disconnected;
>> > >
>> > > @@ -4181,6 +4181,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
>> > > break;
>> > > }
>> > > out:
>> > > + drm_modeset_unlock(&mgr->base.lock);
>>
>> Isn't this supposed to be unlocked only by
>> drm_helper_probe_detect_ctx() / drm_helper_probe_detect() ?
>
> Maybe adding a comment to that effect would be helpful for the future.
>
> Alex
>
>>this is different lock, above function mentioned is locking/unlocking the global connection_mutex, that is required always locked during the atomic >check/commit. Here we are talking about MST topology manager mutex "mgr->base.lock".
>
>>For normal non-bond MST, it's ok, the calling sequence for detecting
>>MST connector status is dp_mst_connector_detect
>>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>>->drm_dp_mst_detect_port (where mgr->base.lock is locked)
>
>> Then for the bond MST case, to figure out if the sibling connectors
>> are also connected, so that the bonding is possible, we need detect
>> two or more connectors >in single dp_mst_connector_detect call
>
>>dp_mst_connector_detect ->mst->mst_fw_cbs->detect_port_ctx =
>>dp_mst_detect_port ->drm_dp_mst_detect_port (where mgr->base.lock is
>>locked) dp_mst_find_sibling_connector
>>->mst->mst_fw_cbs->detect_port_ctx = dp_mst_detect_port
>>->drm_dp_mst_detect_port (blocked by mgr->base.lock)
>
>>
>> > > +fail:
>> > > drm_dp_mst_topology_put_port(port);
>> > > return ret;
>> > > }
>> >
>> > --
>> > Cheers,
>> > Lyude Paul (she/her)
>> > Software Engineer at Red Hat
>> >
--
Jani Nikula, Intel