From: Hans de Goede <hdego...@redhat.com> commit 0ff0705a2ef2929e9326c95df48bdbebb0dafaad upstream.
Lockdep reports an AB BA lock inversion between ucsi_init() and ucsi_handle_connector_change(): AB order: 1. ucsi_init takes ucsi->ppm_lock (it runs with that locked for the duration of the function) 2. usci_init eventually end up calling ucsi_register_displayport, which takes ucsi_connector->lock BA order: 1. ucsi_handle_connector_change work is started, takes ucsi_connector->lock 2. ucsi_handle_connector_change calls ucsi_send_command which takes ucsi->ppm_lock The ppm_lock really only needs to be hold during 2 functions: ucsi_reset_ppm() and ucsi_run_command(). This commit fixes the AB BA lock inversion by making ucsi_init drop the ucsi->ppm_lock before it starts registering ports; and replacing any ucsi_run_command() calls after this point with ucsi_send_command() (which is a wrapper around run_command taking the lock while handling the command). Some of the replacing of ucsi_run_command with ucsi_send_command in the helpers used during port registration also fixes a number of code paths after registration which call ucsi_run_command() without holding the ppm_lock: 1. ucsi_altmode_update_active() call in ucsi/displayport.c 2. ucsi_register_altmodes() call from ucsi_handle_connector_change() (through ucsi_partner_change()) Cc: sta...@vger.kernel.org Signed-off-by: Hans de Goede <hdego...@redhat.com> Acked-by: Heikki Krogerus <heikki.kroge...@linux.intel.com> Reviewed-by: Guenter Roeck <li...@roeck-us.net> Link: https://lore.kernel.org/r/20200809141904.4317-2-hdego...@redhat.com Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/usb/typec/ucsi/ucsi.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -205,7 +205,7 @@ void ucsi_altmode_update_active(struct u int i; command = UCSI_GET_CURRENT_CAM | UCSI_CONNECTOR_NUMBER(con->num); - ret = ucsi_run_command(con->ucsi, command, &cur, sizeof(cur)); + ret = ucsi_send_command(con->ucsi, command, &cur, sizeof(cur)); if (ret < 0) { if (con->ucsi->version > 0x0100) { dev_err(con->ucsi->dev, @@ -354,7 +354,7 @@ ucsi_register_altmodes_nvidia(struct ucs command |= UCSI_GET_ALTMODE_RECIPIENT(recipient); command |= UCSI_GET_ALTMODE_CONNECTOR_NUMBER(con->num); command |= UCSI_GET_ALTMODE_OFFSET(i); - len = ucsi_run_command(con->ucsi, command, &alt, sizeof(alt)); + len = ucsi_send_command(con->ucsi, command, &alt, sizeof(alt)); /* * We are collecting all altmodes first and then registering. * Some type-C device will return zero length data beyond last @@ -431,7 +431,7 @@ static int ucsi_register_altmodes(struct command |= UCSI_GET_ALTMODE_RECIPIENT(recipient); command |= UCSI_GET_ALTMODE_CONNECTOR_NUMBER(con->num); command |= UCSI_GET_ALTMODE_OFFSET(i); - len = ucsi_run_command(con->ucsi, command, alt, sizeof(alt)); + len = ucsi_send_command(con->ucsi, command, alt, sizeof(alt)); if (len <= 0) return len; @@ -904,7 +904,7 @@ static int ucsi_register_port(struct ucs /* Get connector capability */ command = UCSI_GET_CONNECTOR_CAPABILITY; command |= UCSI_CONNECTOR_NUMBER(con->num); - ret = ucsi_run_command(ucsi, command, &con->cap, sizeof(con->cap)); + ret = ucsi_send_command(ucsi, command, &con->cap, sizeof(con->cap)); if (ret < 0) return ret; @@ -953,8 +953,7 @@ static int ucsi_register_port(struct ucs /* Get the status */ command = UCSI_GET_CONNECTOR_STATUS | UCSI_CONNECTOR_NUMBER(con->num); - ret = ucsi_run_command(ucsi, command, &con->status, - sizeof(con->status)); + ret = ucsi_send_command(ucsi, command, &con->status, sizeof(con->status)); if (ret < 0) { dev_err(ucsi->dev, "con%d: failed to get status\n", con->num); return 0; @@ -1044,6 +1043,8 @@ int ucsi_init(struct ucsi *ucsi) goto err_reset; } + mutex_unlock(&ucsi->ppm_lock); + /* Register all connectors */ for (i = 0; i < ucsi->cap.num_connectors; i++) { ret = ucsi_register_port(ucsi, i); @@ -1054,12 +1055,10 @@ int ucsi_init(struct ucsi *ucsi) /* Enable all notifications */ ucsi->ntfy = UCSI_ENABLE_NTFY_ALL; command = UCSI_SET_NOTIFICATION_ENABLE | ucsi->ntfy; - ret = ucsi_run_command(ucsi, command, NULL, 0); + ret = ucsi_send_command(ucsi, command, NULL, 0); if (ret < 0) goto err_unregister; - mutex_unlock(&ucsi->ppm_lock); - return 0; err_unregister: @@ -1071,6 +1070,7 @@ err_unregister: con->port = NULL; } + mutex_lock(&ucsi->ppm_lock); err_reset: ucsi_reset_ppm(ucsi); err:
