Message ID | 20250424084429.3220757-2-akuchynski@chromium.org |
---|---|
State | New |
Headers | show |
Series | Fix thread synchronization issues | expand |
On Thu, Apr 24, 2025 at 08:44:28AM +0000, Andrei Kuchynski wrote: > This patch introduces the ucsi_con_mutex_lock / ucsi_con_mutex_unlock > functions to the UCSI driver. ucsi_con_mutex_lock ensures the connector > mutex is only locked if a connection is established and the partner pointer > is valid. This resolves a deadlock scenario where > ucsi_displayport_remove_partner holds con->mutex waiting for > dp_altmode_work to complete while dp_altmode_work attempts to acquire it. > > Cc: stable@vger.kernel.org > Fixes: af8622f6a585 ("usb: typec: ucsi: Support for DisplayPort alt mode") > Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > --- > drivers/usb/typec/ucsi/displayport.c | 19 +++++++++------- > drivers/usb/typec/ucsi/ucsi.c | 34 ++++++++++++++++++++++++++++ > drivers/usb/typec/ucsi/ucsi.h | 2 ++ > 3 files changed, 47 insertions(+), 8 deletions(-) > > diff --git a/drivers/usb/typec/ucsi/displayport.c b/drivers/usb/typec/ucsi/displayport.c > index 420af5139c70..acd053d4e38c 100644 > --- a/drivers/usb/typec/ucsi/displayport.c > +++ b/drivers/usb/typec/ucsi/displayport.c > @@ -54,7 +54,8 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) > u8 cur = 0; > int ret; > > - mutex_lock(&dp->con->lock); > + if (!ucsi_con_mutex_lock(dp->con)) > + return -ENOTCONN; > > if (!dp->override && dp->initialized) { > const struct typec_altmode *p = typec_altmode_get_partner(alt); > @@ -100,7 +101,7 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) > schedule_work(&dp->work); > ret = 0; > err_unlock: > - mutex_unlock(&dp->con->lock); > + ucsi_con_mutex_unlock(dp->con); > > return ret; > } > @@ -112,7 +113,8 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) > u64 command; > int ret = 0; > > - mutex_lock(&dp->con->lock); > + if (!ucsi_con_mutex_lock(dp->con)) > + return -ENOTCONN; > > if (!dp->override) { > const struct typec_altmode *p = typec_altmode_get_partner(alt); > @@ -144,7 +146,7 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) > schedule_work(&dp->work); > > out_unlock: > - mutex_unlock(&dp->con->lock); > + ucsi_con_mutex_unlock(dp->con); > > return ret; > } > @@ -202,20 +204,21 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, > int cmd = PD_VDO_CMD(header); > int svdm_version; > > - mutex_lock(&dp->con->lock); > + if (!ucsi_con_mutex_lock(dp->con)) > + return -ENOTCONN; > > if (!dp->override && dp->initialized) { > const struct typec_altmode *p = typec_altmode_get_partner(alt); > > dev_warn(&p->dev, > "firmware doesn't support alternate mode overriding\n"); > - mutex_unlock(&dp->con->lock); > + ucsi_con_mutex_unlock(dp->con); > return -EOPNOTSUPP; > } > > svdm_version = typec_altmode_get_svdm_version(alt); > if (svdm_version < 0) { > - mutex_unlock(&dp->con->lock); > + ucsi_con_mutex_unlock(dp->con); > return svdm_version; > } > > @@ -259,7 +262,7 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, > break; > } > > - mutex_unlock(&dp->con->lock); > + ucsi_con_mutex_unlock(dp->con); > > return 0; > } > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c > index e8c7e9dc4930..01ce858a1a2b 100644 > --- a/drivers/usb/typec/ucsi/ucsi.c > +++ b/drivers/usb/typec/ucsi/ucsi.c > @@ -1922,6 +1922,40 @@ void ucsi_set_drvdata(struct ucsi *ucsi, void *data) > } > EXPORT_SYMBOL_GPL(ucsi_set_drvdata); > > +/** > + * ucsi_con_mutex_lock - Acquire the connector mutex > + * @con: The connector interface to lock > + * > + * Returns true on success, false if the connector is disconnected > + */ > +bool ucsi_con_mutex_lock(struct ucsi_connector *con) > +{ > + bool mutex_locked = false; > + bool connected = true; > + > + while (connected && !mutex_locked) { > + mutex_locked = mutex_trylock(&con->lock) != 0; > + connected = UCSI_CONSTAT(con, CONNECTED); > + if (connected && !mutex_locked) > + msleep(20); > + } > + > + connected = connected && con->partner; > + if (!connected && mutex_locked) > + mutex_unlock(&con->lock); > + > + return connected; > +} > + > +/** > + * ucsi_con_mutex_unlock - Release the connector mutex > + * @con: The connector interface to unlock > + */ > +void ucsi_con_mutex_unlock(struct ucsi_connector *con) > +{ > + mutex_unlock(&con->lock); > +} > + > /** > * ucsi_create - Allocate UCSI instance > * @dev: Device interface to the PPM (Platform Policy Manager) > diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h > index 3a2c1762bec1..9c5278a0c5d4 100644 > --- a/drivers/usb/typec/ucsi/ucsi.h > +++ b/drivers/usb/typec/ucsi/ucsi.h > @@ -94,6 +94,8 @@ int ucsi_register(struct ucsi *ucsi); > void ucsi_unregister(struct ucsi *ucsi); > void *ucsi_get_drvdata(struct ucsi *ucsi); > void ucsi_set_drvdata(struct ucsi *ucsi, void *data); > +bool ucsi_con_mutex_lock(struct ucsi_connector *con); > +void ucsi_con_mutex_unlock(struct ucsi_connector *con); > > void ucsi_connector_change(struct ucsi *ucsi, u8 num); > > -- > 2.49.0.805.g082f7c87e0-goog
diff --git a/drivers/usb/typec/ucsi/displayport.c b/drivers/usb/typec/ucsi/displayport.c index 420af5139c70..acd053d4e38c 100644 --- a/drivers/usb/typec/ucsi/displayport.c +++ b/drivers/usb/typec/ucsi/displayport.c @@ -54,7 +54,8 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) u8 cur = 0; int ret; - mutex_lock(&dp->con->lock); + if (!ucsi_con_mutex_lock(dp->con)) + return -ENOTCONN; if (!dp->override && dp->initialized) { const struct typec_altmode *p = typec_altmode_get_partner(alt); @@ -100,7 +101,7 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) schedule_work(&dp->work); ret = 0; err_unlock: - mutex_unlock(&dp->con->lock); + ucsi_con_mutex_unlock(dp->con); return ret; } @@ -112,7 +113,8 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) u64 command; int ret = 0; - mutex_lock(&dp->con->lock); + if (!ucsi_con_mutex_lock(dp->con)) + return -ENOTCONN; if (!dp->override) { const struct typec_altmode *p = typec_altmode_get_partner(alt); @@ -144,7 +146,7 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) schedule_work(&dp->work); out_unlock: - mutex_unlock(&dp->con->lock); + ucsi_con_mutex_unlock(dp->con); return ret; } @@ -202,20 +204,21 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, int cmd = PD_VDO_CMD(header); int svdm_version; - mutex_lock(&dp->con->lock); + if (!ucsi_con_mutex_lock(dp->con)) + return -ENOTCONN; if (!dp->override && dp->initialized) { const struct typec_altmode *p = typec_altmode_get_partner(alt); dev_warn(&p->dev, "firmware doesn't support alternate mode overriding\n"); - mutex_unlock(&dp->con->lock); + ucsi_con_mutex_unlock(dp->con); return -EOPNOTSUPP; } svdm_version = typec_altmode_get_svdm_version(alt); if (svdm_version < 0) { - mutex_unlock(&dp->con->lock); + ucsi_con_mutex_unlock(dp->con); return svdm_version; } @@ -259,7 +262,7 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, break; } - mutex_unlock(&dp->con->lock); + ucsi_con_mutex_unlock(dp->con); return 0; } diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c index e8c7e9dc4930..01ce858a1a2b 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1922,6 +1922,40 @@ void ucsi_set_drvdata(struct ucsi *ucsi, void *data) } EXPORT_SYMBOL_GPL(ucsi_set_drvdata); +/** + * ucsi_con_mutex_lock - Acquire the connector mutex + * @con: The connector interface to lock + * + * Returns true on success, false if the connector is disconnected + */ +bool ucsi_con_mutex_lock(struct ucsi_connector *con) +{ + bool mutex_locked = false; + bool connected = true; + + while (connected && !mutex_locked) { + mutex_locked = mutex_trylock(&con->lock) != 0; + connected = UCSI_CONSTAT(con, CONNECTED); + if (connected && !mutex_locked) + msleep(20); + } + + connected = connected && con->partner; + if (!connected && mutex_locked) + mutex_unlock(&con->lock); + + return connected; +} + +/** + * ucsi_con_mutex_unlock - Release the connector mutex + * @con: The connector interface to unlock + */ +void ucsi_con_mutex_unlock(struct ucsi_connector *con) +{ + mutex_unlock(&con->lock); +} + /** * ucsi_create - Allocate UCSI instance * @dev: Device interface to the PPM (Platform Policy Manager) diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h index 3a2c1762bec1..9c5278a0c5d4 100644 --- a/drivers/usb/typec/ucsi/ucsi.h +++ b/drivers/usb/typec/ucsi/ucsi.h @@ -94,6 +94,8 @@ int ucsi_register(struct ucsi *ucsi); void ucsi_unregister(struct ucsi *ucsi); void *ucsi_get_drvdata(struct ucsi *ucsi); void ucsi_set_drvdata(struct ucsi *ucsi, void *data); +bool ucsi_con_mutex_lock(struct ucsi_connector *con); +void ucsi_con_mutex_unlock(struct ucsi_connector *con); void ucsi_connector_change(struct ucsi *ucsi, u8 num);
This patch introduces the ucsi_con_mutex_lock / ucsi_con_mutex_unlock functions to the UCSI driver. ucsi_con_mutex_lock ensures the connector mutex is only locked if a connection is established and the partner pointer is valid. This resolves a deadlock scenario where ucsi_displayport_remove_partner holds con->mutex waiting for dp_altmode_work to complete while dp_altmode_work attempts to acquire it. Cc: stable@vger.kernel.org Fixes: af8622f6a585 ("usb: typec: ucsi: Support for DisplayPort alt mode") Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org> --- drivers/usb/typec/ucsi/displayport.c | 19 +++++++++------- drivers/usb/typec/ucsi/ucsi.c | 34 ++++++++++++++++++++++++++++ drivers/usb/typec/ucsi/ucsi.h | 2 ++ 3 files changed, 47 insertions(+), 8 deletions(-)