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* [PATCH BlueZ] mesh: Log D-Bus method call errors
@ 2019-08-20  7:56 Michał Lowas-Rzechonek
  2019-08-28 16:22 ` Gix, Brian
  0 siblings, 1 reply; 7+ messages in thread
From: Michał Lowas-Rzechonek @ 2019-08-20  7:56 UTC (permalink / raw)
  To: linux-bluetooth

If a system is misconfigured, mesh daemon might not have permissions to
call application methods.

This patch causes mesh daemon to log such errors, instead of failing
silently.
---
 mesh/dbus.c    | 19 +++++++++++++++++++
 mesh/dbus.h    |  1 +
 mesh/manager.c | 18 ++++++++++--------
 mesh/mesh.c    |  4 ++--
 mesh/model.c   |  8 ++++----
 5 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/mesh/dbus.c b/mesh/dbus.c
index 6b9694ab7..453f11a68 100644
--- a/mesh/dbus.c
+++ b/mesh/dbus.c
@@ -143,3 +143,22 @@ void dbus_append_dict_entry_basic(struct l_dbus_message_builder *builder,
 	l_dbus_message_builder_leave_variant(builder);
 	l_dbus_message_builder_leave_dict(builder);
 }
+
+void dbus_call_reply(struct l_dbus_message *reply, void *user_data)
+{
+	struct l_dbus_message *msg = user_data;
+
+	if (l_dbus_message_is_error(reply)) {
+		const char *name = NULL;
+		const char *desc = NULL;
+
+		l_dbus_message_get_error(reply, &name, &desc);
+
+		l_error("Failed to call %s.%s on (%s)%s: %s %s",
+					l_dbus_message_get_interface(msg),
+					l_dbus_message_get_member(msg),
+					l_dbus_message_get_destination(msg),
+					l_dbus_message_get_path(msg),
+					name, desc);
+	}
+}
diff --git a/mesh/dbus.h b/mesh/dbus.h
index e7643a59d..fecc800a9 100644
--- a/mesh/dbus.h
+++ b/mesh/dbus.h
@@ -31,3 +31,4 @@ bool dbus_match_interface(struct l_dbus_message_iter *interfaces,
 							const char *match);
 struct l_dbus_message *dbus_error(struct l_dbus_message *msg, int err,
 						const char *description);
+void dbus_call_reply(struct l_dbus_message *reply, void *user_data);
diff --git a/mesh/manager.c b/mesh/manager.c
index cf4782c45..2a2e06780 100644
--- a/mesh/manager.c
+++ b/mesh/manager.c
@@ -114,7 +114,7 @@ static void send_add_failed(const char *owner, const char *path,
 						mesh_prov_status_str(status));
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 
 	free_pending_add_call();
 }
@@ -159,7 +159,7 @@ static bool add_cmplt(void *user_data, uint8_t status,
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
 
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 
 	free_pending_add_call();
 
@@ -175,8 +175,10 @@ static void mgr_prov_data (struct l_dbus_message *reply, void *user_data)
 	if (pending != add_pending)
 		return;
 
-	if (l_dbus_message_is_error(reply))
+	if (l_dbus_message_is_error(reply)) {
+		dbus_call_reply(reply, pending->msg);
 		return;
+	}
 
 	if (!l_dbus_message_get_arguments(reply, "qq", &net_idx, &primary))
 		return;
@@ -189,7 +191,6 @@ static void mgr_prov_data (struct l_dbus_message *reply, void *user_data)
 static bool add_data_get(void *user_data, uint8_t num_ele)
 {
 	struct add_data *pending = user_data;
-	struct l_dbus_message *msg;
 	struct l_dbus *dbus;
 	const char *app_path;
 	const char *sender;
@@ -201,12 +202,13 @@ static bool add_data_get(void *user_data, uint8_t num_ele)
 	app_path = node_get_app_path(add_pending->node);
 	sender = node_get_owner(add_pending->node);
 
-	msg = l_dbus_message_new_method_call(dbus, sender, app_path,
+	pending->msg = l_dbus_message_new_method_call(dbus, sender, app_path,
 						MESH_PROVISIONER_INTERFACE,
 						"RequestProvData");
 
-	l_dbus_message_set_arguments(msg, "y", num_ele);
-	l_dbus_send_with_reply(dbus, msg, mgr_prov_data, add_pending, NULL);
+	l_dbus_message_set_arguments(pending->msg, "y", num_ele);
+	l_dbus_send_with_reply(dbus, pending->msg, mgr_prov_data, add_pending,
+									NULL);
 
 	add_pending->num_ele = num_ele;
 
@@ -362,7 +364,7 @@ static void prov_beacon_recv(void *user_data, struct mesh_io_recv_info *info,
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
 
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 }
 
 static struct l_dbus_message *start_scan_call(struct l_dbus *dbus,
diff --git a/mesh/mesh.c b/mesh/mesh.c
index b660a7ef2..9bd644cab 100644
--- a/mesh/mesh.c
+++ b/mesh/mesh.c
@@ -303,7 +303,7 @@ static void send_join_failed(const char *owner, const char *path,
 						"JoinFailed");
 
 	l_dbus_message_set_arguments(msg, "s", mesh_prov_status_str(status));
-	l_dbus_send(dbus_get_bus(), msg);
+	l_dbus_send_with_reply(dbus_get_bus(), msg, dbus_call_reply, msg, NULL);
 
 	free_pending_join_call(true);
 }
@@ -343,7 +343,7 @@ static bool prov_complete_cb(void *user_data, uint8_t status,
 
 	l_dbus_message_set_arguments(msg, "t", l_get_be64(token));
 
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 
 	free_pending_join_call(false);
 
diff --git a/mesh/model.c b/mesh/model.c
index 8f3d67ecf..328a0756d 100644
--- a/mesh/model.c
+++ b/mesh/model.c
@@ -251,7 +251,7 @@ static void config_update_model_pub_period(struct mesh_node *node,
 	l_dbus_message_builder_leave_array(builder);
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 }
 
 static void append_dict_uint16_array(struct l_dbus_message_builder *builder,
@@ -292,7 +292,7 @@ static void config_update_model_bindings(struct mesh_node *node,
 	l_dbus_message_builder_leave_array(builder);
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 }
 
 static void forward_model(void *a, void *b)
@@ -764,7 +764,7 @@ static void send_dev_key_msg_rcvd(struct mesh_node *node, uint8_t ele_idx,
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
 
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 }
 
 static void send_msg_rcvd(struct mesh_node *node, uint8_t ele_idx, bool is_sub,
@@ -797,7 +797,7 @@ static void send_msg_rcvd(struct mesh_node *node, uint8_t ele_idx, bool is_sub,
 
 	l_dbus_message_builder_finalize(builder);
 	l_dbus_message_builder_destroy(builder);
-	l_dbus_send(dbus, msg);
+	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
 }
 
 bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,
-- 
2.19.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-20  7:56 [PATCH BlueZ] mesh: Log D-Bus method call errors Michał Lowas-Rzechonek
@ 2019-08-28 16:22 ` Gix, Brian
  2019-08-29  9:59   ` michal.lowas-rzechonek
  0 siblings, 1 reply; 7+ messages in thread
From: Gix, Brian @ 2019-08-28 16:22 UTC (permalink / raw)
  To: michal.lowas-rzechonek, linux-bluetooth

Hi Michał,


On Tue, 2019-08-20 at 09:56 +0200, Michał Lowas-Rzechonek wrote:
> If a system is misconfigured, mesh daemon might not have permissions to
> call application methods.
> 
> This patch causes mesh daemon to log such errors, instead of failing
> silently.

Some of these Replies for error checking are waurented, I think...  Particularily when there is required
information that needs to be sent to the Application during Provisioning, for instance.

But sometimes we expect the application to be "away" for normal reasons (it is intended as a forground app, for
instance) where I am not sure we want to require the response... For instance the method calls in model.c that
occur when a remote node has sent a message.

The Non-Reply version of send (towards the apps) was actually a design decision, since we don't want the
*daemon* to exhast d-bus resources, depending on replies from Apps that are ignoring the messages we are
sending.  This could negatively impact the daemon's ability to interact with perhaps better behaved
applications.  I think every reply required message persists for up to 30 seconds.

I think our rule of thumb should be requiring a response when the daemon needs to know that the App has
successfully handled critical information so for instance YES for:

AddNodeComplete()   // Provisioner App *must* know when the remote node has accepted Prov 
			Data, and the remote Device Keys should perhaps be discarded if
			they are for nodes the Prov App doesn't know about.

JoinComplete()      // Token *must* be successfully delivered, and perhaps Node deleted if
			no App knows the accessing token

RequestProvData()   // Obviously here, the provisioning cannot procede without the data

But I don't think any of the others is it critical for the daemon to know the message has been processed. And a
prime assumption in mesh is "Any discrete OTA message might be lost".

> ---
>  mesh/dbus.c    | 19 +++++++++++++++++++
>  mesh/dbus.h    |  1 +
>  mesh/manager.c | 18 ++++++++++--------
>  mesh/mesh.c    |  4 ++--
>  mesh/model.c   |  8 ++++----
>  5 files changed, 36 insertions(+), 14 deletions(-)
> 
> diff --git a/mesh/dbus.c b/mesh/dbus.c
> index 6b9694ab7..453f11a68 100644
> --- a/mesh/dbus.c
> +++ b/mesh/dbus.c
> @@ -143,3 +143,22 @@ void dbus_append_dict_entry_basic(struct l_dbus_message_builder *builder,
>  	l_dbus_message_builder_leave_variant(builder);
>  	l_dbus_message_builder_leave_dict(builder);
>  }
> +
> +void dbus_call_reply(struct l_dbus_message *reply, void *user_data)
> +{
> +	struct l_dbus_message *msg = user_data;
> +
> +	if (l_dbus_message_is_error(reply)) {
> +		const char *name = NULL;
> +		const char *desc = NULL;
> +
> +		l_dbus_message_get_error(reply, &name, &desc);
> +
> +		l_error("Failed to call %s.%s on (%s)%s: %s %s",
> +					l_dbus_message_get_interface(msg),
> +					l_dbus_message_get_member(msg),
> +					l_dbus_message_get_destination(msg),
> +					l_dbus_message_get_path(msg),
> +					name, desc);
> +	}
> +}
> diff --git a/mesh/dbus.h b/mesh/dbus.h
> index e7643a59d..fecc800a9 100644
> --- a/mesh/dbus.h
> +++ b/mesh/dbus.h
> @@ -31,3 +31,4 @@ bool dbus_match_interface(struct l_dbus_message_iter *interfaces,
>  							const char *match);
>  struct l_dbus_message *dbus_error(struct l_dbus_message *msg, int err,
>  						const char *description);
> +void dbus_call_reply(struct l_dbus_message *reply, void *user_data);
> diff --git a/mesh/manager.c b/mesh/manager.c
> index cf4782c45..2a2e06780 100644
> --- a/mesh/manager.c
> +++ b/mesh/manager.c
> @@ -114,7 +114,7 @@ static void send_add_failed(const char *owner, const char *path,
>  						mesh_prov_status_str(status));
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  
>  	free_pending_add_call();
>  }
> @@ -159,7 +159,7 @@ static bool add_cmplt(void *user_data, uint8_t status,
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
>  
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  
>  	free_pending_add_call();
>  
> @@ -175,8 +175,10 @@ static void mgr_prov_data (struct l_dbus_message *reply, void *user_data)
>  	if (pending != add_pending)
>  		return;
>  
> -	if (l_dbus_message_is_error(reply))
> +	if (l_dbus_message_is_error(reply)) {
> +		dbus_call_reply(reply, pending->msg);
>  		return;
> +	}
>  
>  	if (!l_dbus_message_get_arguments(reply, "qq", &net_idx, &primary))
>  		return;
> @@ -189,7 +191,6 @@ static void mgr_prov_data (struct l_dbus_message *reply, void *user_data)
>  static bool add_data_get(void *user_data, uint8_t num_ele)
>  {
>  	struct add_data *pending = user_data;
> -	struct l_dbus_message *msg;
>  	struct l_dbus *dbus;
>  	const char *app_path;
>  	const char *sender;
> @@ -201,12 +202,13 @@ static bool add_data_get(void *user_data, uint8_t num_ele)
>  	app_path = node_get_app_path(add_pending->node);
>  	sender = node_get_owner(add_pending->node);
>  
> -	msg = l_dbus_message_new_method_call(dbus, sender, app_path,
> +	pending->msg = l_dbus_message_new_method_call(dbus, sender, app_path,
>  						MESH_PROVISIONER_INTERFACE,
>  						"RequestProvData");
>  
> -	l_dbus_message_set_arguments(msg, "y", num_ele);
> -	l_dbus_send_with_reply(dbus, msg, mgr_prov_data, add_pending, NULL);
> +	l_dbus_message_set_arguments(pending->msg, "y", num_ele);
> +	l_dbus_send_with_reply(dbus, pending->msg, mgr_prov_data, add_pending,
> +									NULL);
>  
>  	add_pending->num_ele = num_ele;
>  
> @@ -362,7 +364,7 @@ static void prov_beacon_recv(void *user_data, struct mesh_io_recv_info *info,
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
>  
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  }
>  
>  static struct l_dbus_message *start_scan_call(struct l_dbus *dbus,
> diff --git a/mesh/mesh.c b/mesh/mesh.c
> index b660a7ef2..9bd644cab 100644
> --- a/mesh/mesh.c
> +++ b/mesh/mesh.c
> @@ -303,7 +303,7 @@ static void send_join_failed(const char *owner, const char *path,
>  						"JoinFailed");
>  
>  	l_dbus_message_set_arguments(msg, "s", mesh_prov_status_str(status));
> -	l_dbus_send(dbus_get_bus(), msg);
> +	l_dbus_send_with_reply(dbus_get_bus(), msg, dbus_call_reply, msg, NULL);
>  
>  	free_pending_join_call(true);
>  }
> @@ -343,7 +343,7 @@ static bool prov_complete_cb(void *user_data, uint8_t status,
>  
>  	l_dbus_message_set_arguments(msg, "t", l_get_be64(token));
>  
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  
>  	free_pending_join_call(false);
>  
> diff --git a/mesh/model.c b/mesh/model.c
> index 8f3d67ecf..328a0756d 100644
> --- a/mesh/model.c
> +++ b/mesh/model.c
> @@ -251,7 +251,7 @@ static void config_update_model_pub_period(struct mesh_node *node,
>  	l_dbus_message_builder_leave_array(builder);
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  }
>  
>  static void append_dict_uint16_array(struct l_dbus_message_builder *builder,
> @@ -292,7 +292,7 @@ static void config_update_model_bindings(struct mesh_node *node,
>  	l_dbus_message_builder_leave_array(builder);
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  }
>  
>  static void forward_model(void *a, void *b)
> @@ -764,7 +764,7 @@ static void send_dev_key_msg_rcvd(struct mesh_node *node, uint8_t ele_idx,
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
>  
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  }
>  
>  static void send_msg_rcvd(struct mesh_node *node, uint8_t ele_idx, bool is_sub,
> @@ -797,7 +797,7 @@ static void send_msg_rcvd(struct mesh_node *node, uint8_t ele_idx, bool is_sub,
>  
>  	l_dbus_message_builder_finalize(builder);
>  	l_dbus_message_builder_destroy(builder);
> -	l_dbus_send(dbus, msg);
> +	l_dbus_send_with_reply(dbus, msg, dbus_call_reply, msg, NULL);
>  }
>  
>  bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-28 16:22 ` Gix, Brian
@ 2019-08-29  9:59   ` michal.lowas-rzechonek
  2019-08-29 18:38     ` Gix, Brian
  0 siblings, 1 reply; 7+ messages in thread
From: michal.lowas-rzechonek @ 2019-08-29  9:59 UTC (permalink / raw)
  To: Gix, Brian; +Cc: linux-bluetooth

Hi Brian,

On 08/28, Gix, Brian wrote:
> On Tue, 2019-08-20 at 09:56 +0200, Michał Lowas-Rzechonek wrote:
> > If a system is misconfigured, mesh daemon might not have permissions to
> > call application methods.
> >
> > This patch causes mesh daemon to log such errors, instead of failing
> > silently.
>
> Some of these Replies for error checking are warranted, I think...
> Particularily when there is required information that needs to be sent
> to the Application during Provisioning, for instance.
>
> But sometimes we expect the application to be "away" for normal
> reasons (it is intended as a foreground app, for instance) where I am
> not sure we want to require the response... For instance the method
> calls in model.c that occur when a remote node has sent a message.

Yes, these calls were my primary concern here.

Note that D-Bus calls do *not* happen if the application is not attached
(node->owner is NULL).

> The Non-Reply version of send (towards the apps) was actually a design
> decision, since we don't want the *daemon* to exhast d-bus resources,
> depending on replies from Apps that are ignoring the messages we are
> sending.
>
> This could negatively impact the daemon's ability to
> interact with perhaps better behaved applications.  I think every
> reply required message persists for up to 30 seconds.

True.

Since most of the application-side methods do not return anything (and
rightly so, because "Any discrete OTA message might be lost"), the
application is free to do whatever is pleases with the payload,
including dropping it.

Still, I think that the none of the call handlers on the application
side should *ever* return errors/timeouts over D-Bus.

I'm arguing that such an application is misbehaving, so it probably
should be promptly detached. That would protect the daemon.

> I think our rule of thumb should be requiring a response when the
> daemon needs to know that the App has successfully handled critical
> information so for instance YES for:
>
> AddNodeComplete()
> JoinComplete()
> RequestProvData()

Agreed.

regards
-- 
Michał Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-29  9:59   ` michal.lowas-rzechonek
@ 2019-08-29 18:38     ` Gix, Brian
  2019-08-29 19:56       ` michal.lowas-rzechonek
  0 siblings, 1 reply; 7+ messages in thread
From: Gix, Brian @ 2019-08-29 18:38 UTC (permalink / raw)
  To: michal.lowas-rzechonek; +Cc: linux-bluetooth

Hi Michał,

On Thu, 2019-08-29 at 11:59 +0200, michal.lowas-rzechonek@silvair.com wrote:
> Hi Brian,
> 
> On 08/28, Gix, Brian wrote:
> > On Tue, 2019-08-20 at 09:56 +0200, Michał Lowas-Rzechonek wrote:
> > > If a system is misconfigured, mesh daemon might not have permissions to
> > > call application methods.
> > > 
> > > This patch causes mesh daemon to log such errors, instead of failing
> > > silently.
> > 
> > Some of these Replies for error checking are warranted, I think...
> > Particularily when there is required information that needs to be sent
> > to the Application during Provisioning, for instance.
> > 
> > But sometimes we expect the application to be "away" for normal
> > reasons (it is intended as a foreground app, for instance) where I am
> > not sure we want to require the response... For instance the method
> > calls in model.c that occur when a remote node has sent a message.
> 
> Yes, these calls were my primary concern here.
> 
> Note that D-Bus calls do *not* happen if the application is not attached
> (node->owner is NULL).

That is true, and we *expect* applications that are attached to handle the socket-signals (that drive d-bus) in
a timely manner...  But I am not sure we have a way to enforce it. 

Certainly, we can simulate a disconnection if an App ignores it's DBus socket signal, but again, we won't know
about that for 30 seconds which seems like forever...  And an App could potentially have a large enough backlog
of messages negatively affecting the daemon before it and corrects it.

> 
> > The Non-Reply version of send (towards the apps) was actually a design
> > decision, since we don't want the *daemon* to exhast d-bus resources,
> > depending on replies from Apps that are ignoring the messages we are
> > sending.
> > 
> > This could negatively impact the daemon's ability to
> > interact with perhaps better behaved applications.  I think every
> > reply required message persists for up to 30 seconds.
> 
> True.
> 
> Since most of the application-side methods do not return anything (and
> rightly so, because "Any discrete OTA message might be lost"), the
> application is free to do whatever is pleases with the payload,
> including dropping it.
> 
> Still, I think that the none of the call handlers on the application
> side should *ever* return errors/timeouts over D-Bus.
> 
> I'm arguing that such an application is misbehaving, so it probably
> should be promptly detached. That would protect the daemon.
> 
> > I think our rule of thumb should be requiring a response when the
> > daemon needs to know that the App has successfully handled critical
> > information so for instance YES for:
> > 
> > AddNodeComplete()
> > JoinComplete()
> > RequestProvData()
> 
> Agreed.
> 
> regards

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-29 18:38     ` Gix, Brian
@ 2019-08-29 19:56       ` michal.lowas-rzechonek
  2019-08-29 20:07         ` Gix, Brian
  0 siblings, 1 reply; 7+ messages in thread
From: michal.lowas-rzechonek @ 2019-08-29 19:56 UTC (permalink / raw)
  To: Gix, Brian; +Cc: linux-bluetooth

Hi Brian,

On 08/29, Gix, Brian wrote:
> That is true, and we *expect* applications that are attached to handle
> the socket-signals (that drive d-bus) in a timely manner...  But I am
> not sure we have a way to enforce it.
> 
> Certainly, we can simulate a disconnection if an App ignores it's DBus
> socket signal, but again, we won't know about that for 30 seconds
> which seems like forever...  And an App could potentially have a large
> enough backlog of messages negatively affecting the daemon before it
> and corrects it.

This seems like a limitation of ELL:
1. There doesn't seem to be an explicit API to set timeouts on method
   calls, so if the application takes too long to handle method calls,
   message_list hashmap in l_dbus struct would indeed grow quite large.
2. There doesn't seem to be a way to set an upper limit of pending
   messages (or maybe even message rate?) in l_dbus connection.

Still, looking at ell/dbus.c, it seems it should be possible to manually
call l_dbus_cancel after obtaining serial number of the method call
message, using _dbus_message_get_serial from dbus-private.h (yeah, I
know).

Anyway, I think a better approach would be to submit patches to ELL
implementing these two features, and then use these additions in meshd.
Does that sound acceptable from your POV?

By the way, it seems that bluetoothd suffers from the same problem with
regards to external GATT services/characteristics/descriptors.

regards
-- 
Michał Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-29 19:56       ` michal.lowas-rzechonek
@ 2019-08-29 20:07         ` Gix, Brian
  2019-08-30  5:47           ` michal.lowas-rzechonek
  0 siblings, 1 reply; 7+ messages in thread
From: Gix, Brian @ 2019-08-29 20:07 UTC (permalink / raw)
  To: michal.lowas-rzechonek; +Cc: linux-bluetooth

Hi Micha³,

> On Aug 29, 2019, at 12:56 PM, "michal.lowas-rzechonek@silvair.com" <michal.lowas-rzechonek@silvair.com> wrote:
> 
> Hi Brian,
> 
>> On 08/29, Gix, Brian wrote:
>> That is true, and we *expect* applications that are attached to handle
>> the socket-signals (that drive d-bus) in a timely manner...  But I am
>> not sure we have a way to enforce it.
>> 
>> Certainly, we can simulate a disconnection if an App ignores it's DBus
>> socket signal, but again, we won't know about that for 30 seconds
>> which seems like forever...  And an App could potentially have a large
>> enough backlog of messages negatively affecting the daemon before it
>> and corrects it.
> 
> This seems like a limitation of ELL:
> 1. There doesn't seem to be an explicit API to set timeouts on method
>   calls, so if the application takes too long to handle method calls,
>   message_list hashmap in l_dbus struct would indeed grow quite large.
> 2. There doesn't seem to be a way to set an upper limit of pending
>   messages (or maybe even message rate?) in l_dbus connection.
> 
> Still, looking at ell/dbus.c, it seems it should be possible to manually
> call l_dbus_cancel after obtaining serial number of the method call
> message, using _dbus_message_get_serial from dbus-private.h (yeah, I
> know).
> 
> Anyway, I think a better approach would be to submit patches to ELL
> implementing these two features, and then use these additions in meshd.
> Does that sound acceptable from your POV?

I’m not sure I agree with you on the need to expose and adjust  DBus message timeouts, however, I think you are probably correct that the correct place to have that conversation is on the ELL reflector, which can be accessed here:

https://lists.01.org/mailman/listinfo/ell

I still feel though, that you are trying to solve a pre-deployment “debugging” issue by requiring DBus responses for messages that don’t require them.


> 
> By the way, it seems that bluetoothd suffers from the same problem with
> regards to external GATT services/characteristics/descriptors.
> 
> regards
> -- 
> Micha³ Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>
> Silvair http://silvair.com
> Jasnogórska 44, 31-358 Krakow, POLAND

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH BlueZ] mesh: Log D-Bus method call errors
  2019-08-29 20:07         ` Gix, Brian
@ 2019-08-30  5:47           ` michal.lowas-rzechonek
  0 siblings, 0 replies; 7+ messages in thread
From: michal.lowas-rzechonek @ 2019-08-30  5:47 UTC (permalink / raw)
  To: Gix, Brian; +Cc: linux-bluetooth

Brian,

On 08/29, Gix, Brian wrote:
> > Anyway, I think a better approach would be to submit patches to ELL
> > implementing these two features, and then use these additions in meshd.
> > Does that sound acceptable from your POV?
> 
> I still feel though, that you are trying to solve a pre-deployment
> “debugging” issue by requiring DBus responses for messages that don’t
> require them.

I think you're right.

Let's drop this patch, and I'll try to come up with something that would
cover only "important" methods you mentioned earlier.

regards
-- 
Michał Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, back to index

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-20  7:56 [PATCH BlueZ] mesh: Log D-Bus method call errors Michał Lowas-Rzechonek
2019-08-28 16:22 ` Gix, Brian
2019-08-29  9:59   ` michal.lowas-rzechonek
2019-08-29 18:38     ` Gix, Brian
2019-08-29 19:56       ` michal.lowas-rzechonek
2019-08-29 20:07         ` Gix, Brian
2019-08-30  5:47           ` michal.lowas-rzechonek

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