From 66db383439b51b1aa920f3579da644fb5fdb2b7c Mon Sep 17 00:00:00 2001 From: Lv Zheng Date: Thu, 11 Jun 2015 13:21:51 +0800 Subject: [PATCH] ACPI / EC: Fix a code coverity issue when QR_EC transactions are failed. When the QR_EC transaction fails, the EC_FLAGS_QUERY_PENDING flag prevents the event handling work queue from being scheduled again. Though there shouldn't be failed QR_EC transactions, and this gap was efficiently used for catching and learning the SCI_EVT clearing timing compliance issues, we need to fix this as we are not fully compatible with all platforms/Windows to handle SCI_EVT clearing timing correctly. Fixing this gives the EC driver the chances to recover from a state machine failure. So this patch fixes this issue. When nr_pending_queries drops to 0, it clears EC_FLAGS_QUERY_PENDING at the proper position for different modes in order to ensure that the SCI_EVT handling can proceed. In order to be clearer for future ec_event_clearing modes, all checks in this patch are written in the inclusive style, not the exclusive style. Cc: 3.16+ # 3.16+ Signed-off-by: Lv Zheng Signed-off-by: Rafael J. Wysocki --- drivers/acpi/ec.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 79817ce164c1..9d4761d2f6b7 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -512,7 +512,8 @@ static void advance_transaction(struct acpi_ec *ec) */ if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) { if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT && - test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags)) { + (!ec->nr_pending_queries || + test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) { clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags); acpi_ec_complete_query(ec); } @@ -1065,6 +1066,17 @@ static void acpi_ec_event_handler(struct work_struct *work) (void)acpi_ec_query(ec, NULL); spin_lock_irqsave(&ec->lock, flags); ec->nr_pending_queries--; + /* + * Before exit, make sure that this work item can be + * scheduled again. There might be QR_EC failures, leaving + * EC_FLAGS_QUERY_PENDING uncleared and preventing this work + * item from being scheduled again. + */ + if (!ec->nr_pending_queries) { + if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS || + ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY) + acpi_ec_complete_query(ec); + } } spin_unlock_irqrestore(&ec->lock, flags); -- 2.20.1