drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
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 <quic_rsr@quicinc.com>
---
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;
}
--
2.7.4Oh! wow thank you for catching this: Reviewed-by: Lyude Paul <lyude@redhat.com> 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 <quic_rsr@quicinc.com> > --- > 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
On Fri, Sep 22, 2023 at 03:02:23PM -0400, Lyude Paul wrote: > > Oh! wow thank you for catching this: > > Reviewed-by: Lyude Paul <lyude@redhat.com> > > 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 <quic_rsr@quicinc.com> > > --- > > 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 <imre.deak@intel.com> 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 <lyude@redhat.com> > > > > 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 <quic_rsr@quicinc.com> > > > --- > > > 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 <alexdeucher@gmail.com> Sent: Monday, September 25, 2023 8:27 PM To: imre.deak@intel.com Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> 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 <imre.deak@intel.com> 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 <lyude@redhat.com> > > > > 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 <quic_rsr@quicinc.com> > > > --- > > > 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 <alexdeucher@gmail.com>; imre.deak@intel.com Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect -----Original Message----- From: Alex Deucher <alexdeucher@gmail.com> Sent: Monday, September 25, 2023 8:27 PM To: imre.deak@intel.com Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> 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 <imre.deak@intel.com> 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 <lyude@redhat.com> > > > > 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 <quic_rsr@quicinc.com> > > > --- > > > 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 > >
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' <alexdeucher@gmail.com>; 'imre.deak@intel.com' <imre.deak@intel.com> Cc: 'Lyude Paul' <lyude@redhat.com>; 'Jani Nikula' <jani.nikula@intel.com>; 'Jeff Layton' <jlayton@kernel.org>; 'linux-kernel@vger.kernel.org' <linux-kernel@vger.kernel.org>; 'dri-devel@lists.freedesktop.org' <dri-devel@lists.freedesktop.org>; 'Wayne Lin' <Wayne.Lin@amd.com>; 'Alex Deucher' <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> 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 <alexdeucher@gmail.com>; imre.deak@intel.com Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect -----Original Message----- From: Alex Deucher <alexdeucher@gmail.com> Sent: Monday, September 25, 2023 8:27 PM To: imre.deak@intel.com Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> 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 <imre.deak@intel.com> 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 <lyude@redhat.com> > > > > 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 <quic_rsr@quicinc.com> > > > --- > > > 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 <rsr@qti.qualcomm.com> 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/877coak8o3.fsf@intel.com > > Regards, > Ramya SR > > -----Original Message----- > From: Ramya SR > Sent: Thursday, September 28, 2023 7:55 AM > To: 'Alex Deucher' <alexdeucher@gmail.com>; 'imre.deak@intel.com' <imre.deak@intel.com> > Cc: 'Lyude Paul' <lyude@redhat.com>; 'Jani Nikula' <jani.nikula@intel.com>; 'Jeff Layton' <jlayton@kernel.org>; 'linux-kernel@vger.kernel.org' <linux-kernel@vger.kernel.org>; 'dri-devel@lists.freedesktop.org' <dri-devel@lists.freedesktop.org>; 'Wayne Lin' <Wayne.Lin@amd.com>; 'Alex Deucher' <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> > 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 <alexdeucher@gmail.com>; imre.deak@intel.com > Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> > Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect > > > > -----Original Message----- > From: Alex Deucher <alexdeucher@gmail.com> > Sent: Monday, September 25, 2023 8:27 PM > To: imre.deak@intel.com > Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> > 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 <imre.deak@intel.com> 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 <lyude@redhat.com> >> > >> > 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 <quic_rsr@quicinc.com> >> > > --- >> > > 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
On Thu, 28 Sep 2023, Ramya SR <rsr@qti.qualcomm.com> 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 <alexdeucher@gmail.com>; imre.deak@intel.com > Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> > Subject: RE: [PATCH v1] drm/dp/mst: fix missing modeset unlock for MST port detect > > > > -----Original Message----- > From: Alex Deucher <alexdeucher@gmail.com> > Sent: Monday, September 25, 2023 8:27 PM > To: imre.deak@intel.com > Cc: Lyude Paul <lyude@redhat.com>; Jani Nikula <jani.nikula@intel.com>; Jeff Layton <jlayton@kernel.org>; linux-kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Wayne Lin <Wayne.Lin@amd.com>; Alex Deucher <alexander.deucher@amd.com>; Ramya SR (QUIC) <quic_rsr@quicinc.com> > 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 <imre.deak@intel.com> 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 <lyude@redhat.com> >> > >> > 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 <quic_rsr@quicinc.com> >> > > --- >> > > 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
…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 <lyude@redhat.com> > > > > 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 <quic_rsr@quicinc.com> > > > --- > > > 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
Gentle Reminder. Please review the commit.
-----Original Message-----
From: Ramya SR (QUIC) <quic_rsr@quicinc.com>
Sent: Friday, September 15, 2023 10:25 AM
To: David Airlie <airlied@gmail.com>; Daniel Vetter <daniel@ffwll.ch>; Lyude Paul <lyude@redhat.com>; Wayne Lin <Wayne.Lin@amd.com>; Jani Nikula <jani.nikula@intel.com>; Imre Deak <imre.deak@intel.com>; Alex Deucher <alexander.deucher@amd.com>; Jeff Layton <jlayton@kernel.org>; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org
Cc: Ramya SR (QUIC) <quic_rsr@quicinc.com>
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 <quic_rsr@quicinc.com>
---
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;
}
--
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