linux-kernel - [PATCH v2 06/10] ACPI/EC: Add a warning message to indicate event storms.

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Message-Id: <c22b03a036ea97a94cfe7a2d878ff63c93174d43.1405391679.git.lv.zheng@intel.com>
Date:	Tue, 15 Jul 2014 11:15:00 +0800
From:	Lv Zheng <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <len.brown@...el.com>
Cc:	Lv Zheng <lv.zheng@...el.com>, Lv Zheng <zetalog@...il.com>,
	<linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org
Subject: [PATCH v2 06/10] ACPI/EC: Add a warning message to indicate event storms.

This patch splits query handler scheduling into a new seperate function
acpi_ec_notify_query_handlers() and adds a warning message in it to
indicate a BIOS bug. It is reported that EC event storm can happen in case
there is no handler prepared for the event. No functional changes.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=78091
Reported-by: Steffen Weber <steffen.weber@...il.com>
Signed-off-by: Lv Zheng <lv.zheng@...el.com>
---
 drivers/acpi/ec.c |   29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index cf83872..8817836 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -669,32 +669,39 @@ static void acpi_ec_run(void *cxt)
 	acpi_ec_put_query_handler(handler);
 }
 
-static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data)
+static int acpi_ec_notify_query_handlers(struct acpi_ec *ec, u8 query_bit)
 {
-	u8 value = 0;
-	int status;
 	struct acpi_ec_query_handler *handler;
 
-	status = acpi_ec_query_unlocked(ec, &value);
-	if (data)
-		*data = value;
-	if (status)
-		return status;
-
 	list_for_each_entry(handler, &ec->list, node) {
-		if (value == handler->query_bit) {
+		if (query_bit == handler->query_bit) {
 			/* have custom handler for this bit */
 			handler = acpi_ec_get_query_handler(handler);
 			pr_debug("push query execution (0x%2x) on queue\n",
-				value);
+				 query_bit);
 			return acpi_os_execute((handler->func) ?
 				OSL_NOTIFY_HANDLER : OSL_GPE_HANDLER,
 				acpi_ec_run, handler);
 		}
 	}
+	pr_warn_once("BIOS bug: no handler for query (0x%02x)\n", query_bit);
 	return 0;
 }
 
+static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data)
+{
+	u8 value = 0;
+	int status;
+
+	status = acpi_ec_query_unlocked(ec, &value);
+	if (data)
+		*data = value;
+	if (status)
+		return status;
+
+	return acpi_ec_notify_query_handlers(ec, value);
+}
+
 static void acpi_ec_gpe_query(void *ec_cxt)
 {
 	struct acpi_ec *ec = ec_cxt;
-- 
1.7.10

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