The patch below does not apply to the 4.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 66db383439b51b1aa920f3579da644fb5fdb2b7c Mon Sep 17 00:00:00 2001
From: Lv Zheng <lv.zheng@xxxxxxxxx>
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+ <stable@xxxxxxxxxxxxxxx> # 3.16+
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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);
--
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