@@ -813,10 +813,11 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev,
if (ret == -ENOPROTOOPT) {
dev_dbg(ec_dev->dev,
"GET_NEXT_EVENT returned invalid version error.\n");
+ mutex_lock(&ec_dev->lock);
ret = cros_ec_get_host_command_version_mask(ec_dev,
EC_CMD_GET_NEXT_EVENT,
&ver_mask);
- if (ret < 0 || ver_mask == 0)
+ if (ret < 0 || ver_mask == 0) {
/*
* Do not change the MKBP supported version if we can't
* obtain supported version correctly. Please note that
@@ -824,11 +825,14 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev,
* EC_RES_INVALID_VERSION which means that the command
* is present.
*/
+ mutex_unlock(&ec_dev->lock);
return -ENOPROTOOPT;
+ }
ec_dev->mkbp_event_supported = fls(ver_mask);
dev_dbg(ec_dev->dev, "MKBP support version changed to %u\n",
ec_dev->mkbp_event_supported - 1);
+ mutex_unlock(&ec_dev->lock);
/* Try to get next event with new MKBP support version set. */
ret = get_next_event(ec_dev);
The cros_ec_get_host_command_version_mask() function requires that the caller must have ec_dev->lock mutex before calling it. This requirement was not met and as a result it was possible that two commands were sent to the device at the same time. The problem was observed while using UART backend which doesn't use any additional locks, unlike SPI backend which locks the controller until response is received. Fixes: f74c7557ed0d ("platform/chrome: cros_ec_proto: Update version on GET_NEXT_EVENT failure") Cc: stable@vger.kernel.org Signed-off-by: Patryk Duda <patrykd@google.com> --- The f74c7557ed0d patch was tested with Fingerprint MCU (FPMCU) that uses SPI to communicate with chipset. At that time, UART FPMCU had the same version of GET_NEXT_EVENT command in RO and RW, so the MKBP version was never updated in this case. Version 3 of GET_NEXT_EVENT command was recently added to CrosEC. As a result MKBP version is also updated when UART FPMCU is used which exposed this problem. Best regards, Patryk V1 -> V2 - Added missing mutex_unlock() on cros_ec_get_host_command_version_mask() failure drivers/platform/chrome/cros_ec_proto.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)