[PATCH v2 0/3] soc: qcom: pmic_glink: v6.11-rc bug fixes

[PATCH v2 0/3] soc: qcom: pmic_glink: v6.11-rc bug fixes

[Bjorn Andersson]

Amit and Johan both reported a NULL pointer dereference in the
pmic_glink client code during initialization, and Stephen Boyd pointed
out the problem (race condition).

While investigating, and writing the fix, I noticed that
ucsi_unregister() is called in atomic context but tries to sleep, and I
also noticed that the condition for when to inform the pmic_glink client
drivers when the remote has gone down is just wrong.

So, let's fix all three.

As mentioned in the commit message for the UCSI fix, I have a series in
the works that makes the GLINK callback happen in a sleepable context,
which would remove the need for the clients list to be protected by a
spinlock, and removing the work scheduling. This is however not -rc
material...

In addition to the NULL pointer dereference, there is the -ECANCELED
issue reported here:
https://lore.kernel.org/all/Zqet8iInnDhnxkT9@hovoldconsulting.com/
Johan reports that these fixes do not address that issue.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
---
Changes in v2:
- Refer to the correct commit in the ucsi_unregister() patch.
- Updated wording in the same commit message about the new error message
  in the log.
- Changed the data type of the introduced state variables, opted to go
  for a bool as we only represent two states (and I would like to
  further clean this up going forward)
- Initialized the spinlock
- Link to v1: https://lore.kernel.org/r/20240818-pmic-glink-v6-11-races-v1-0-f87c577e0bc9@quicinc.com

---
Bjorn Andersson (3):
      soc: qcom: pmic_glink: Fix race during initialization
      usb: typec: ucsi: Move unregister out of atomic section
      soc: qcom: pmic_glink: Actually communicate with remote goes down

 drivers/power/supply/qcom_battmgr.c   | 16 ++++++++-----
 drivers/soc/qcom/pmic_glink.c         | 40 ++++++++++++++++++++++----------
 drivers/soc/qcom/pmic_glink_altmode.c | 17 +++++++++-----
 drivers/usb/typec/ucsi/ucsi_glink.c   | 43 ++++++++++++++++++++++++++---------
 include/linux/soc/qcom/pmic_glink.h   | 11 +++++----
 5 files changed, 87 insertions(+), 40 deletions(-)
---
base-commit: 2fd613d27928293eaa87788b10e8befb6805cd42
change-id: 20240818-pmic-glink-v6-11-races-363f5964c339

Best regards,
-- 
Bjorn Andersson <quic_bjorande@quicinc.com>

[PATCH v2 1/3] soc: qcom: pmic_glink: Fix race during initialization

[Bjorn Andersson]

As pointed out by Stephen Boyd it is possible that during initialization
of the pmic_glink child drivers, the protection-domain notifiers fires,
and the associated work is scheduled, before the client registration
returns and as a result the local "client" pointer has been initialized.

The outcome of this is a NULL pointer dereference as the "client"
pointer is blindly dereferenced.

Timeline provided by Stephen:
 CPU0                               CPU1
 ----                               ----
 ucsi->client = NULL;
 devm_pmic_glink_register_client()
  client->pdr_notify(client->priv, pg->client_state)
   pmic_glink_ucsi_pdr_notify()
    schedule_work(&ucsi->register_work)
    <schedule away>
                                    pmic_glink_ucsi_register()
                                     ucsi_register()
                                      pmic_glink_ucsi_read_version()
                                       pmic_glink_ucsi_read()
                                        pmic_glink_ucsi_read()
                                         pmic_glink_send(ucsi->client)
                                         <client is NULL BAD>
 ucsi->client = client // Too late!

This code is identical across the altmode, battery manager and usci
child drivers.

Resolve this by splitting the allocation of the "client" object and the
registration thereof into two operations.

This only happens if the protection domain registry is populated at the
time of registration, which by the introduction of commit '1ebcde047c54
("soc: qcom: add pd-mapper implementation")' became much more likely.

Reported-by: Amit Pundir <amit.pundir@linaro.org>
Closes: https://lore.kernel.org/all/CAMi1Hd2_a7TjA7J9ShrAbNOd_CoZ3D87twmO5t+nZxC9sX18tA@mail.gmail.com/
Reported-by: Johan Hovold <johan@kernel.org>
Closes: https://lore.kernel.org/all/ZqiyLvP0gkBnuekL@hovoldconsulting.com/
Reported-by: Stephen Boyd <swboyd@chromium.org>
Closes: https://lore.kernel.org/all/CAE-0n52JgfCBWiFQyQWPji8cq_rCsviBpW-m72YitgNfdaEhQg@mail.gmail.com/
Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
Cc: stable@vger.kernel.org
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
---
 drivers/power/supply/qcom_battmgr.c   | 16 ++++++++++------
 drivers/soc/qcom/pmic_glink.c         | 28 ++++++++++++++++++----------
 drivers/soc/qcom/pmic_glink_altmode.c | 17 +++++++++++------
 drivers/usb/typec/ucsi/ucsi_glink.c   | 16 ++++++++++------
 include/linux/soc/qcom/pmic_glink.h   | 11 ++++++-----
 5 files changed, 55 insertions(+), 33 deletions(-)

diff --git a/drivers/power/supply/qcom_battmgr.c b/drivers/power/supply/qcom_battmgr.c
index 49bef4a5ac3f..df90a470c51a 100644
--- a/drivers/power/supply/qcom_battmgr.c
+++ b/drivers/power/supply/qcom_battmgr.c
@@ -1387,12 +1387,16 @@ static int qcom_battmgr_probe(struct auxiliary_device *adev,
 					     "failed to register wireless charing power supply\n");
 	}
 
-	battmgr->client = devm_pmic_glink_register_client(dev,
-							  PMIC_GLINK_OWNER_BATTMGR,
-							  qcom_battmgr_callback,
-							  qcom_battmgr_pdr_notify,
-							  battmgr);
-	return PTR_ERR_OR_ZERO(battmgr->client);
+	battmgr->client = devm_pmic_glink_new_client(dev, PMIC_GLINK_OWNER_BATTMGR,
+						     qcom_battmgr_callback,
+						     qcom_battmgr_pdr_notify,
+						     battmgr);
+	if (IS_ERR(battmgr->client))
+		return PTR_ERR(battmgr->client);
+
+	pmic_glink_register_client(battmgr->client);
+
+	return 0;
 }
 
 static const struct auxiliary_device_id qcom_battmgr_id_table[] = {
diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index 9ebc0ba35947..58ec91767d79 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -66,15 +66,14 @@ static void _devm_pmic_glink_release_client(struct device *dev, void *res)
 	spin_unlock_irqrestore(&pg->client_lock, flags);
 }
 
-struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
-							  unsigned int id,
-							  void (*cb)(const void *, size_t, void *),
-							  void (*pdr)(void *, int),
-							  void *priv)
+struct pmic_glink_client *devm_pmic_glink_new_client(struct device *dev,
+						     unsigned int id,
+						     void (*cb)(const void *, size_t, void *),
+						     void (*pdr)(void *, int),
+						     void *priv)
 {
 	struct pmic_glink_client *client;
 	struct pmic_glink *pg = dev_get_drvdata(dev->parent);
-	unsigned long flags;
 
 	client = devres_alloc(_devm_pmic_glink_release_client, sizeof(*client), GFP_KERNEL);
 	if (!client)
@@ -85,6 +84,18 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
 	client->cb = cb;
 	client->pdr_notify = pdr;
 	client->priv = priv;
+	INIT_LIST_HEAD(&client->node);
+
+	devres_add(dev, client);
+
+	return client;
+}
+EXPORT_SYMBOL_GPL(devm_pmic_glink_new_client);
+
+void pmic_glink_register_client(struct pmic_glink_client *client)
+{
+	struct pmic_glink *pg = client->pg;
+	unsigned long flags;
 
 	mutex_lock(&pg->state_lock);
 	spin_lock_irqsave(&pg->client_lock, flags);
@@ -95,11 +106,8 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
 	spin_unlock_irqrestore(&pg->client_lock, flags);
 	mutex_unlock(&pg->state_lock);
 
-	devres_add(dev, client);
-
-	return client;
 }
-EXPORT_SYMBOL_GPL(devm_pmic_glink_register_client);
+EXPORT_SYMBOL_GPL(pmic_glink_register_client);
 
 int pmic_glink_send(struct pmic_glink_client *client, void *data, size_t len)
 {
diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
index 1e0808b3cb93..e4f5059256e5 100644
--- a/drivers/soc/qcom/pmic_glink_altmode.c
+++ b/drivers/soc/qcom/pmic_glink_altmode.c
@@ -520,12 +520,17 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
 			return ret;
 	}
 
-	altmode->client = devm_pmic_glink_register_client(dev,
-							  altmode->owner_id,
-							  pmic_glink_altmode_callback,
-							  pmic_glink_altmode_pdr_notify,
-							  altmode);
-	return PTR_ERR_OR_ZERO(altmode->client);
+	altmode->client = devm_pmic_glink_new_client(dev,
+						     altmode->owner_id,
+						     pmic_glink_altmode_callback,
+						     pmic_glink_altmode_pdr_notify,
+						     altmode);
+	if (IS_ERR(altmode->client))
+		return PTR_ERR(altmode->client);
+
+	pmic_glink_register_client(altmode->client);
+
+	return 0;
 }
 
 static const struct auxiliary_device_id pmic_glink_altmode_id_table[] = {
diff --git a/drivers/usb/typec/ucsi/ucsi_glink.c b/drivers/usb/typec/ucsi/ucsi_glink.c
index 16c328497e0b..ac53a81c2a81 100644
--- a/drivers/usb/typec/ucsi/ucsi_glink.c
+++ b/drivers/usb/typec/ucsi/ucsi_glink.c
@@ -367,12 +367,16 @@ static int pmic_glink_ucsi_probe(struct auxiliary_device *adev,
 		ucsi->port_orientation[port] = desc;
 	}
 
-	ucsi->client = devm_pmic_glink_register_client(dev,
-						       PMIC_GLINK_OWNER_USBC,
-						       pmic_glink_ucsi_callback,
-						       pmic_glink_ucsi_pdr_notify,
-						       ucsi);
-	return PTR_ERR_OR_ZERO(ucsi->client);
+	ucsi->client = devm_pmic_glink_new_client(dev, PMIC_GLINK_OWNER_USBC,
+						  pmic_glink_ucsi_callback,
+						  pmic_glink_ucsi_pdr_notify,
+						  ucsi);
+	if (IS_ERR(ucsi->client))
+		return PTR_ERR(ucsi->client);
+
+	pmic_glink_register_client(ucsi->client);
+
+	return 0;
 }
 
 static void pmic_glink_ucsi_remove(struct auxiliary_device *adev)
diff --git a/include/linux/soc/qcom/pmic_glink.h b/include/linux/soc/qcom/pmic_glink.h
index fd124aa18c81..aedde76d7e13 100644
--- a/include/linux/soc/qcom/pmic_glink.h
+++ b/include/linux/soc/qcom/pmic_glink.h
@@ -23,10 +23,11 @@ struct pmic_glink_hdr {
 
 int pmic_glink_send(struct pmic_glink_client *client, void *data, size_t len);
 
-struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
-							  unsigned int id,
-							  void (*cb)(const void *, size_t, void *),
-							  void (*pdr)(void *, int),
-							  void *priv);
+struct pmic_glink_client *devm_pmic_glink_new_client(struct device *dev,
+						     unsigned int id,
+						     void (*cb)(const void *, size_t, void *),
+						     void (*pdr)(void *, int),
+						     void *priv);
+void pmic_glink_register_client(struct pmic_glink_client *client);
 
 #endif

-- 
2.34.1

[PATCH v2 2/3] usb: typec: ucsi: Move unregister out of atomic section

[Bjorn Andersson]

Commit '635ce0db8956 ("soc: qcom: pmic_glink: don't traverse clients
list without a lock")' moved the pmic_glink client list under a
spinlock, as it is accessed by the rpmsg/glink callback, which in turn
is invoked from IRQ context.

This means that ucsi_unregister() is now called from IRQ context, which
isn't feasible as it's expecting a sleepable context. An effort is under
way to get GLINK to invoke its callbacks in a sleepable context, but
until then lets schedule the unregistration.

A side effect of this is that ucsi_unregister() can now happen
after the remote processor, and thereby the communication link with it, is
gone. pmic_glink_send() is amended with a check to avoid the resulting NULL
pointer dereference.
This does however result in the user being informed about this error by
the following entry in the kernel log:

  ucsi_glink.pmic_glink_ucsi pmic_glink.ucsi.0: failed to send UCSI write request: -5

Fixes: 635ce0db8956 ("soc: qcom: pmic_glink: don't traverse clients list without a lock")
Cc: stable@vger.kernel.org
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
---
 drivers/soc/qcom/pmic_glink.c       | 10 +++++++++-
 drivers/usb/typec/ucsi/ucsi_glink.c | 27 ++++++++++++++++++++++-----
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index 58ec91767d79..e4747f1d3da5 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -112,8 +112,16 @@ EXPORT_SYMBOL_GPL(pmic_glink_register_client);
 int pmic_glink_send(struct pmic_glink_client *client, void *data, size_t len)
 {
 	struct pmic_glink *pg = client->pg;
+	int ret;
 
-	return rpmsg_send(pg->ept, data, len);
+	mutex_lock(&pg->state_lock);
+	if (!pg->ept)
+		ret = -ECONNRESET;
+	else
+		ret = rpmsg_send(pg->ept, data, len);
+	mutex_unlock(&pg->state_lock);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(pmic_glink_send);
 
diff --git a/drivers/usb/typec/ucsi/ucsi_glink.c b/drivers/usb/typec/ucsi/ucsi_glink.c
index ac53a81c2a81..bb6244f21e0a 100644
--- a/drivers/usb/typec/ucsi/ucsi_glink.c
+++ b/drivers/usb/typec/ucsi/ucsi_glink.c
@@ -68,6 +68,9 @@ struct pmic_glink_ucsi {
 
 	struct work_struct notify_work;
 	struct work_struct register_work;
+	spinlock_t state_lock;
+	bool ucsi_registered;
+	bool pd_running;
 
 	u8 read_buf[UCSI_BUF_SIZE];
 };
@@ -244,8 +247,20 @@ static void pmic_glink_ucsi_notify(struct work_struct *work)
 static void pmic_glink_ucsi_register(struct work_struct *work)
 {
 	struct pmic_glink_ucsi *ucsi = container_of(work, struct pmic_glink_ucsi, register_work);
+	unsigned long flags;
+	bool pd_running;
 
-	ucsi_register(ucsi->ucsi);
+	spin_lock_irqsave(&ucsi->state_lock, flags);
+	pd_running = ucsi->pd_running;
+	spin_unlock_irqrestore(&ucsi->state_lock, flags);
+
+	if (!ucsi->ucsi_registered && pd_running) {
+		ucsi_register(ucsi->ucsi);
+		ucsi->ucsi_registered = true;
+	} else if (ucsi->ucsi_registered && !pd_running) {
+		ucsi_unregister(ucsi->ucsi);
+		ucsi->ucsi_registered = false;
+	}
 }
 
 static void pmic_glink_ucsi_callback(const void *data, size_t len, void *priv)
@@ -269,11 +284,12 @@ static void pmic_glink_ucsi_callback(const void *data, size_t len, void *priv)
 static void pmic_glink_ucsi_pdr_notify(void *priv, int state)
 {
 	struct pmic_glink_ucsi *ucsi = priv;
+	unsigned long flags;
 
-	if (state == SERVREG_SERVICE_STATE_UP)
-		schedule_work(&ucsi->register_work);
-	else if (state == SERVREG_SERVICE_STATE_DOWN)
-		ucsi_unregister(ucsi->ucsi);
+	spin_lock_irqsave(&ucsi->state_lock, flags);
+	ucsi->pd_running = state == SERVREG_SERVICE_STATE_UP;
+	spin_unlock_irqrestore(&ucsi->state_lock, flags);
+	schedule_work(&ucsi->register_work);
 }
 
 static void pmic_glink_ucsi_destroy(void *data)
@@ -320,6 +336,7 @@ static int pmic_glink_ucsi_probe(struct auxiliary_device *adev,
 	INIT_WORK(&ucsi->register_work, pmic_glink_ucsi_register);
 	init_completion(&ucsi->read_ack);
 	init_completion(&ucsi->write_ack);
+	spin_lock_init(&ucsi->state_lock);
 	mutex_init(&ucsi->lock);
 
 	ucsi->ucsi = ucsi_create(dev, &pmic_glink_ucsi_ops);

-- 
2.34.1

[PATCH v2 3/3] soc: qcom: pmic_glink: Actually communicate with remote goes down

[Bjorn Andersson]

When the pmic_glink state is UP and we either receive a protection-
domain (PD) notification indicating that the PD is going down, or that
the whole remoteproc is going down, it's expected that the pmic_glink
client instances are notified that their function has gone DOWN.

This is not what the code does, which results in the client state either
not updating, or being wrong in many cases. So let's fix the conditions.

Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
Cc: stable@vger.kernel.org
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
---
 drivers/soc/qcom/pmic_glink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index e4747f1d3da5..cb202a37e8ab 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -191,7 +191,7 @@ static void pmic_glink_state_notify_clients(struct pmic_glink *pg)
 		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
 			new_state = SERVREG_SERVICE_STATE_UP;
 	} else {
-		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
+		if (pg->pdr_state == SERVREG_SERVICE_STATE_DOWN || !pg->ept)
 			new_state = SERVREG_SERVICE_STATE_DOWN;
 	}
 

-- 
2.34.1

Re: [PATCH v2 1/3] soc: qcom: pmic_glink: Fix race during initialization

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 9227 bytes --]

Hi,

On Mon, Aug 19, 2024 at 01:07:45PM GMT, Bjorn Andersson wrote:
> As pointed out by Stephen Boyd it is possible that during initialization
> of the pmic_glink child drivers, the protection-domain notifiers fires,
> and the associated work is scheduled, before the client registration
> returns and as a result the local "client" pointer has been initialized.
> 
> The outcome of this is a NULL pointer dereference as the "client"
> pointer is blindly dereferenced.
> 
> Timeline provided by Stephen:
>  CPU0                               CPU1
>  ----                               ----
>  ucsi->client = NULL;
>  devm_pmic_glink_register_client()
>   client->pdr_notify(client->priv, pg->client_state)
>    pmic_glink_ucsi_pdr_notify()
>     schedule_work(&ucsi->register_work)
>     <schedule away>
>                                     pmic_glink_ucsi_register()
>                                      ucsi_register()
>                                       pmic_glink_ucsi_read_version()
>                                        pmic_glink_ucsi_read()
>                                         pmic_glink_ucsi_read()
>                                          pmic_glink_send(ucsi->client)
>                                          <client is NULL BAD>
>  ucsi->client = client // Too late!
> 
> This code is identical across the altmode, battery manager and usci
> child drivers.
> 
> Resolve this by splitting the allocation of the "client" object and the
> registration thereof into two operations.
> 
> This only happens if the protection domain registry is populated at the
> time of registration, which by the introduction of commit '1ebcde047c54
> ("soc: qcom: add pd-mapper implementation")' became much more likely.
> 
> Reported-by: Amit Pundir <amit.pundir@linaro.org>
> Closes: https://lore.kernel.org/all/CAMi1Hd2_a7TjA7J9ShrAbNOd_CoZ3D87twmO5t+nZxC9sX18tA@mail.gmail.com/
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/all/ZqiyLvP0gkBnuekL@hovoldconsulting.com/
> Reported-by: Stephen Boyd <swboyd@chromium.org>
> Closes: https://lore.kernel.org/all/CAE-0n52JgfCBWiFQyQWPji8cq_rCsviBpW-m72YitgNfdaEhQg@mail.gmail.com/
> Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
> Cc: stable@vger.kernel.org
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> Tested-by: Amit Pundir <amit.pundir@linaro.org>
> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
> ---

I expect this to go through SOC tree:

Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>

-- Sebastian

>  drivers/power/supply/qcom_battmgr.c   | 16 ++++++++++------
>  drivers/soc/qcom/pmic_glink.c         | 28 ++++++++++++++++++----------
>  drivers/soc/qcom/pmic_glink_altmode.c | 17 +++++++++++------
>  drivers/usb/typec/ucsi/ucsi_glink.c   | 16 ++++++++++------
>  include/linux/soc/qcom/pmic_glink.h   | 11 ++++++-----
>  5 files changed, 55 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/power/supply/qcom_battmgr.c b/drivers/power/supply/qcom_battmgr.c
> index 49bef4a5ac3f..df90a470c51a 100644
> --- a/drivers/power/supply/qcom_battmgr.c
> +++ b/drivers/power/supply/qcom_battmgr.c
> @@ -1387,12 +1387,16 @@ static int qcom_battmgr_probe(struct auxiliary_device *adev,
>  					     "failed to register wireless charing power supply\n");
>  	}
>  
> -	battmgr->client = devm_pmic_glink_register_client(dev,
> -							  PMIC_GLINK_OWNER_BATTMGR,
> -							  qcom_battmgr_callback,
> -							  qcom_battmgr_pdr_notify,
> -							  battmgr);
> -	return PTR_ERR_OR_ZERO(battmgr->client);
> +	battmgr->client = devm_pmic_glink_new_client(dev, PMIC_GLINK_OWNER_BATTMGR,
> +						     qcom_battmgr_callback,
> +						     qcom_battmgr_pdr_notify,
> +						     battmgr);
> +	if (IS_ERR(battmgr->client))
> +		return PTR_ERR(battmgr->client);
> +
> +	pmic_glink_register_client(battmgr->client);
> +
> +	return 0;
>  }
>  
>  static const struct auxiliary_device_id qcom_battmgr_id_table[] = {
> diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
> index 9ebc0ba35947..58ec91767d79 100644
> --- a/drivers/soc/qcom/pmic_glink.c
> +++ b/drivers/soc/qcom/pmic_glink.c
> @@ -66,15 +66,14 @@ static void _devm_pmic_glink_release_client(struct device *dev, void *res)
>  	spin_unlock_irqrestore(&pg->client_lock, flags);
>  }
>  
> -struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
> -							  unsigned int id,
> -							  void (*cb)(const void *, size_t, void *),
> -							  void (*pdr)(void *, int),
> -							  void *priv)
> +struct pmic_glink_client *devm_pmic_glink_new_client(struct device *dev,
> +						     unsigned int id,
> +						     void (*cb)(const void *, size_t, void *),
> +						     void (*pdr)(void *, int),
> +						     void *priv)
>  {
>  	struct pmic_glink_client *client;
>  	struct pmic_glink *pg = dev_get_drvdata(dev->parent);
> -	unsigned long flags;
>  
>  	client = devres_alloc(_devm_pmic_glink_release_client, sizeof(*client), GFP_KERNEL);
>  	if (!client)
> @@ -85,6 +84,18 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
>  	client->cb = cb;
>  	client->pdr_notify = pdr;
>  	client->priv = priv;
> +	INIT_LIST_HEAD(&client->node);
> +
> +	devres_add(dev, client);
> +
> +	return client;
> +}
> +EXPORT_SYMBOL_GPL(devm_pmic_glink_new_client);
> +
> +void pmic_glink_register_client(struct pmic_glink_client *client)
> +{
> +	struct pmic_glink *pg = client->pg;
> +	unsigned long flags;
>  
>  	mutex_lock(&pg->state_lock);
>  	spin_lock_irqsave(&pg->client_lock, flags);
> @@ -95,11 +106,8 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
>  	spin_unlock_irqrestore(&pg->client_lock, flags);
>  	mutex_unlock(&pg->state_lock);
>  
> -	devres_add(dev, client);
> -
> -	return client;
>  }
> -EXPORT_SYMBOL_GPL(devm_pmic_glink_register_client);
> +EXPORT_SYMBOL_GPL(pmic_glink_register_client);
>  
>  int pmic_glink_send(struct pmic_glink_client *client, void *data, size_t len)
>  {
> diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
> index 1e0808b3cb93..e4f5059256e5 100644
> --- a/drivers/soc/qcom/pmic_glink_altmode.c
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> @@ -520,12 +520,17 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
>  			return ret;
>  	}
>  
> -	altmode->client = devm_pmic_glink_register_client(dev,
> -							  altmode->owner_id,
> -							  pmic_glink_altmode_callback,
> -							  pmic_glink_altmode_pdr_notify,
> -							  altmode);
> -	return PTR_ERR_OR_ZERO(altmode->client);
> +	altmode->client = devm_pmic_glink_new_client(dev,
> +						     altmode->owner_id,
> +						     pmic_glink_altmode_callback,
> +						     pmic_glink_altmode_pdr_notify,
> +						     altmode);
> +	if (IS_ERR(altmode->client))
> +		return PTR_ERR(altmode->client);
> +
> +	pmic_glink_register_client(altmode->client);
> +
> +	return 0;
>  }
>  
>  static const struct auxiliary_device_id pmic_glink_altmode_id_table[] = {
> diff --git a/drivers/usb/typec/ucsi/ucsi_glink.c b/drivers/usb/typec/ucsi/ucsi_glink.c
> index 16c328497e0b..ac53a81c2a81 100644
> --- a/drivers/usb/typec/ucsi/ucsi_glink.c
> +++ b/drivers/usb/typec/ucsi/ucsi_glink.c
> @@ -367,12 +367,16 @@ static int pmic_glink_ucsi_probe(struct auxiliary_device *adev,
>  		ucsi->port_orientation[port] = desc;
>  	}
>  
> -	ucsi->client = devm_pmic_glink_register_client(dev,
> -						       PMIC_GLINK_OWNER_USBC,
> -						       pmic_glink_ucsi_callback,
> -						       pmic_glink_ucsi_pdr_notify,
> -						       ucsi);
> -	return PTR_ERR_OR_ZERO(ucsi->client);
> +	ucsi->client = devm_pmic_glink_new_client(dev, PMIC_GLINK_OWNER_USBC,
> +						  pmic_glink_ucsi_callback,
> +						  pmic_glink_ucsi_pdr_notify,
> +						  ucsi);
> +	if (IS_ERR(ucsi->client))
> +		return PTR_ERR(ucsi->client);
> +
> +	pmic_glink_register_client(ucsi->client);
> +
> +	return 0;
>  }
>  
>  static void pmic_glink_ucsi_remove(struct auxiliary_device *adev)
> diff --git a/include/linux/soc/qcom/pmic_glink.h b/include/linux/soc/qcom/pmic_glink.h
> index fd124aa18c81..aedde76d7e13 100644
> --- a/include/linux/soc/qcom/pmic_glink.h
> +++ b/include/linux/soc/qcom/pmic_glink.h
> @@ -23,10 +23,11 @@ struct pmic_glink_hdr {
>  
>  int pmic_glink_send(struct pmic_glink_client *client, void *data, size_t len);
>  
> -struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
> -							  unsigned int id,
> -							  void (*cb)(const void *, size_t, void *),
> -							  void (*pdr)(void *, int),
> -							  void *priv);
> +struct pmic_glink_client *devm_pmic_glink_new_client(struct device *dev,
> +						     unsigned int id,
> +						     void (*cb)(const void *, size_t, void *),
> +						     void (*pdr)(void *, int),
> +						     void *priv);
> +void pmic_glink_register_client(struct pmic_glink_client *client);
>  
>  #endif
> 
> -- 
> 2.34.1
> 

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Re: [PATCH v2 2/3] usb: typec: ucsi: Move unregister out of atomic section

[Johan Hovold]

On Mon, Aug 19, 2024 at 01:07:46PM -0700, Bjorn Andersson wrote:
> Commit '635ce0db8956 ("soc: qcom: pmic_glink: don't traverse clients

Looks like you copied the wrong SHA again. This should be

	9329933699b3 ("soc: qcom: pmic_glink: Make client-lock non-sleeping")

as we discussed.

> list without a lock")' moved the pmic_glink client list under a
> spinlock, as it is accessed by the rpmsg/glink callback, which in turn
> is invoked from IRQ context.
> 
> This means that ucsi_unregister() is now called from IRQ context, which

And this should be "atomic context" as pdr notifications are done from
a worker thread.

> isn't feasible as it's expecting a sleepable context. An effort is under
> way to get GLINK to invoke its callbacks in a sleepable context, but
> until then lets schedule the unregistration.
> 
> A side effect of this is that ucsi_unregister() can now happen
> after the remote processor, and thereby the communication link with it, is
> gone. pmic_glink_send() is amended with a check to avoid the resulting NULL
> pointer dereference.
> This does however result in the user being informed about this error by
> the following entry in the kernel log:
> 
>   ucsi_glink.pmic_glink_ucsi pmic_glink.ucsi.0: failed to send UCSI write request: -5
> 
> Fixes: 635ce0db8956 ("soc: qcom: pmic_glink: don't traverse clients list without a lock")

Fixes: 9329933699b3 ("soc: qcom: pmic_glink: Make client-lock non-sleeping")

> Cc: stable@vger.kernel.org
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Tested-by: Amit Pundir <amit.pundir@linaro.org>
> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>

> @@ -269,11 +284,12 @@ static void pmic_glink_ucsi_callback(const void *data, size_t len, void *priv)
>  static void pmic_glink_ucsi_pdr_notify(void *priv, int state)
>  {
>  	struct pmic_glink_ucsi *ucsi = priv;
> +	unsigned long flags;
>  
> -	if (state == SERVREG_SERVICE_STATE_UP)
> -		schedule_work(&ucsi->register_work);
> -	else if (state == SERVREG_SERVICE_STATE_DOWN)
> -		ucsi_unregister(ucsi->ucsi);
> +	spin_lock_irqsave(&ucsi->state_lock, flags);
> +	ucsi->pd_running = state == SERVREG_SERVICE_STATE_UP;

Add parentheses for readability?

> +	spin_unlock_irqrestore(&ucsi->state_lock, flags);
> +	schedule_work(&ucsi->register_work);
>  }
>  
>  static void pmic_glink_ucsi_destroy(void *data)
> @@ -320,6 +336,7 @@ static int pmic_glink_ucsi_probe(struct auxiliary_device *adev,
>  	INIT_WORK(&ucsi->register_work, pmic_glink_ucsi_register);
>  	init_completion(&ucsi->read_ack);
>  	init_completion(&ucsi->write_ack);
> +	spin_lock_init(&ucsi->state_lock);
>  	mutex_init(&ucsi->lock);
>  
>  	ucsi->ucsi = ucsi_create(dev, &pmic_glink_ucsi_ops);

Looks good otherwise:

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>

Johan

Re: [PATCH v2 1/3] soc: qcom: pmic_glink: Fix race during initialization

[Johan Hovold]

On Mon, Aug 19, 2024 at 01:07:45PM -0700, Bjorn Andersson wrote:
> As pointed out by Stephen Boyd it is possible that during initialization
> of the pmic_glink child drivers, the protection-domain notifiers fires,
> and the associated work is scheduled, before the client registration
> returns and as a result the local "client" pointer has been initialized.
> 
> The outcome of this is a NULL pointer dereference as the "client"
> pointer is blindly dereferenced.
> 
> Timeline provided by Stephen:
>  CPU0                               CPU1
>  ----                               ----
>  ucsi->client = NULL;
>  devm_pmic_glink_register_client()
>   client->pdr_notify(client->priv, pg->client_state)
>    pmic_glink_ucsi_pdr_notify()
>     schedule_work(&ucsi->register_work)
>     <schedule away>
>                                     pmic_glink_ucsi_register()
>                                      ucsi_register()
>                                       pmic_glink_ucsi_read_version()
>                                        pmic_glink_ucsi_read()
>                                         pmic_glink_ucsi_read()
>                                          pmic_glink_send(ucsi->client)
>                                          <client is NULL BAD>
>  ucsi->client = client // Too late!
> 
> This code is identical across the altmode, battery manager and usci
> child drivers.
> 
> Resolve this by splitting the allocation of the "client" object and the
> registration thereof into two operations.
> 
> This only happens if the protection domain registry is populated at the
> time of registration, which by the introduction of commit '1ebcde047c54
> ("soc: qcom: add pd-mapper implementation")' became much more likely.
> 
> Reported-by: Amit Pundir <amit.pundir@linaro.org>
> Closes: https://lore.kernel.org/all/CAMi1Hd2_a7TjA7J9ShrAbNOd_CoZ3D87twmO5t+nZxC9sX18tA@mail.gmail.com/
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/all/ZqiyLvP0gkBnuekL@hovoldconsulting.com/
> Reported-by: Stephen Boyd <swboyd@chromium.org>
> Closes: https://lore.kernel.org/all/CAE-0n52JgfCBWiFQyQWPji8cq_rCsviBpW-m72YitgNfdaEhQg@mail.gmail.com/
> Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
> Cc: stable@vger.kernel.org
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> Tested-by: Amit Pundir <amit.pundir@linaro.org>
> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>

> diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
> index 9ebc0ba35947..58ec91767d79 100644
> --- a/drivers/soc/qcom/pmic_glink.c
> +++ b/drivers/soc/qcom/pmic_glink.c
> @@ -66,15 +66,14 @@ static void _devm_pmic_glink_release_client(struct device *dev, void *res)
>  	spin_unlock_irqrestore(&pg->client_lock, flags);
>  }
>  
> -struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
> -							  unsigned int id,
> -							  void (*cb)(const void *, size_t, void *),
> -							  void (*pdr)(void *, int),
> -							  void *priv)
> +struct pmic_glink_client *devm_pmic_glink_new_client(struct device *dev,

Please consider renaming this one

	devm_pmic_glink_alloc_client()

(or devm_pmic_glink_client_alloc()) which is more conventional for
kernel code than using "new".

> +						     unsigned int id,
> +						     void (*cb)(const void *, size_t, void *),
> +						     void (*pdr)(void *, int),
> +						     void *priv)
>  {
>  	struct pmic_glink_client *client;
>  	struct pmic_glink *pg = dev_get_drvdata(dev->parent);
> -	unsigned long flags;
>  
>  	client = devres_alloc(_devm_pmic_glink_release_client, sizeof(*client), GFP_KERNEL);
>  	if (!client)

Looks good otherwise:

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>

Johan

Re: [PATCH v2 3/3] soc: qcom: pmic_glink: Actually communicate with remote goes down

[Johan Hovold]

On Mon, Aug 19, 2024 at 01:07:47PM -0700, Bjorn Andersson wrote:
> When the pmic_glink state is UP and we either receive a protection-
> domain (PD) notification indicating that the PD is going down, or that
> the whole remoteproc is going down, it's expected that the pmic_glink
> client instances are notified that their function has gone DOWN.
> 
> This is not what the code does, which results in the client state either
> not updating, or being wrong in many cases. So let's fix the conditions.

> @@ -191,7 +191,7 @@ static void pmic_glink_state_notify_clients(struct pmic_glink *pg)
>  		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
>  			new_state = SERVREG_SERVICE_STATE_UP;
>  	} else {
> -		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
> +		if (pg->pdr_state == SERVREG_SERVICE_STATE_DOWN || !pg->ept)
>  			new_state = SERVREG_SERVICE_STATE_DOWN;
>  	}

I guess you could drop the outer conditional

	if (pg->client_state != SERVREG_SERVICE_STATE_UP) {

	} else {

	}

here to make this a bit more readable, but that's for a separate patch.

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>

Johan

Re: [PATCH v2 0/3] soc: qcom: pmic_glink: v6.11-rc bug fixes

[Johan Hovold]

On Mon, Aug 19, 2024 at 01:07:44PM -0700, Bjorn Andersson wrote:
> Amit and Johan both reported a NULL pointer dereference in the
> pmic_glink client code during initialization, and Stephen Boyd pointed
> out the problem (race condition).
> 
> While investigating, and writing the fix, I noticed that
> ucsi_unregister() is called in atomic context but tries to sleep, and I
> also noticed that the condition for when to inform the pmic_glink client
> drivers when the remote has gone down is just wrong.
> 
> So, let's fix all three.

> Changes in v2:
> - Refer to the correct commit in the ucsi_unregister() patch.
> - Updated wording in the same commit message about the new error message
>   in the log.
> - Changed the data type of the introduced state variables, opted to go
>   for a bool as we only represent two states (and I would like to
>   further clean this up going forward)
> - Initialized the spinlock
> - Link to v1: https://lore.kernel.org/r/20240818-pmic-glink-v6-11-races-v1-0-f87c577e0bc9@quicinc.com
> 
> ---
> Bjorn Andersson (3):
>       soc: qcom: pmic_glink: Fix race during initialization
>       usb: typec: ucsi: Move unregister out of atomic section
>       soc: qcom: pmic_glink: Actually communicate with remote goes down

Tested-by: Johan Hovold <johan+linaro@kernel.org>

Re: [PATCH v2 3/3] soc: qcom: pmic_glink: Actually communicate with remote goes down

[Johan Hovold]

On Tue, Aug 20, 2024 at 09:07:10AM +0200, Johan Hovold wrote:
> On Mon, Aug 19, 2024 at 01:07:47PM -0700, Bjorn Andersson wrote:
> > When the pmic_glink state is UP and we either receive a protection-
> > domain (PD) notification indicating that the PD is going down, or that
> > the whole remoteproc is going down, it's expected that the pmic_glink
> > client instances are notified that their function has gone DOWN.
> > 
> > This is not what the code does, which results in the client state either
> > not updating, or being wrong in many cases. So let's fix the conditions.

And I believe you meant

	s/with/when/

in the patch Subject.

Johan