[PATCH v2 5/5] 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
---
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 79817ce..9d4761d 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, >flags)) {
+ (!ec->nr_pending_queries ||
+test_bit(EC_FLAGS_QUERY_GUARDING, >flags))) {
clear_bit(EC_FLAGS_QUERY_GUARDING, >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(>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(>lock, flags);
--
1.7.10
--
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[PATCH v2 5/5] 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+ sta...@vger.kernel.org # 3.16+
Signed-off-by: Lv Zheng lv.zh...@intel.com
---
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 79817ce..9d4761d 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);
--
1.7.10
--
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the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
