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+ <stable@vger.kernel.org> # 3.16+ Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -512,7 +512,8 @@ static void advance_transaction(struct acpi_ec *ec)
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*/
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if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
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if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
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test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags)) {
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(!ec->nr_pending_queries ||
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test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
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clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
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acpi_ec_complete_query(ec);
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}
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@ -1065,6 +1066,17 @@ static void acpi_ec_event_handler(struct work_struct *work)
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(void)acpi_ec_query(ec, NULL);
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spin_lock_irqsave(&ec->lock, flags);
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ec->nr_pending_queries--;
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/*
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* Before exit, make sure that this work item can be
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* scheduled again. There might be QR_EC failures, leaving
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* EC_FLAGS_QUERY_PENDING uncleared and preventing this work
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* item from being scheduled again.
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*/
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if (!ec->nr_pending_queries) {
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if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
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ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY)
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acpi_ec_complete_query(ec);
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}
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}
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spin_unlock_irqrestore(&ec->lock, flags);
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