linux-kernel - [PATCH 3/6] ACPI / EC: Convert event handling work queue into loop style.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon,  8 Jun 2015 13:28:04 +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 3/6] ACPI / EC: Convert event handling work queue into loop style.

During the period that a work queue is scheduled (queued up for run) but
hasn't been run, second schedule_work() could fail. This may not lead to
the loss of queries because QR_EC is always ensured to be submitted after
the work queue has been in the running state.

Thus except the logging message changes, this patch is just a no-op. But
the event handling work queue can be changed into the loop style to allow
us to control the code in a more flexible way (for example, adding
event=0x00 termination condition in the loop).

Signed-off-by: Lv Zheng <lv.zheng@...el.com>
Tested-by: Gabriele Mazzotta <gabriele.mzt@...il.com>
Tested-by: Tigran Gabrielyan <tigrangab@...il.com>
Tested-by: Adrien D <ghbdtn@...nmailbox.org>
---
 drivers/acpi/ec.c       |   33 ++++++++++++++++++++++++---------
 drivers/acpi/internal.h |    1 +
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index b956dbc..7a30f59 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -384,7 +384,9 @@ static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
 static void acpi_ec_submit_query(struct acpi_ec *ec)
 {
 	if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
-		ec_dbg_req("Event started");
+		ec_dbg_evt("Command(%s) submitted/blocked",
+			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
+		ec->nr_pending_queries++;
 		schedule_work(&ec->work);
 	}
 }
@@ -393,7 +395,8 @@ static void acpi_ec_complete_query(struct acpi_ec *ec)
 {
 	if (test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
-		ec_dbg_req("Event stopped");
+		ec_dbg_evt("Command(%s) unblocked",
+			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 	}
 }
 
@@ -460,8 +463,8 @@ static void advance_transaction(struct acpi_ec *ec)
 				if (t->rlen == t->ri) {
 					ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 					if (t->command == ACPI_EC_COMMAND_QUERY)
-						ec_dbg_req("Command(%s) hardware completion",
-							   acpi_ec_cmd_string(t->command));
+						ec_dbg_evt("Command(%s) completed by hardware",
+							   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 					wakeup = true;
 				}
 			} else
@@ -479,8 +482,8 @@ static void advance_transaction(struct acpi_ec *ec)
 			ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
 			t->rdata[t->ri++] = 0x00;
 			ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
-			ec_dbg_req("Command(%s) software completion",
-				   acpi_ec_cmd_string(t->command));
+			ec_dbg_evt("Command(%s) completed by software",
+				   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 			wakeup = true;
 		} else if ((status & ACPI_EC_FLAG_IBF) == 0) {
 			acpi_ec_write_cmd(ec, t->command);
@@ -950,11 +953,23 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
 	return result;
 }
 
-static void acpi_ec_gpe_poller(struct work_struct *work)
+static void acpi_ec_event_handler(struct work_struct *work)
 {
+	unsigned long flags;
 	struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
 
-	acpi_ec_query(ec, NULL);
+	ec_dbg_evt("Event started");
+
+	spin_lock_irqsave(&ec->lock, flags);
+	while (ec->nr_pending_queries) {
+		spin_unlock_irqrestore(&ec->lock, flags);
+		(void)acpi_ec_query(ec, NULL);
+		spin_lock_irqsave(&ec->lock, flags);
+		ec->nr_pending_queries--;
+	}
+	spin_unlock_irqrestore(&ec->lock, flags);
+
+	ec_dbg_evt("Event stopped");
 }
 
 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
@@ -1029,7 +1044,7 @@ static struct acpi_ec *make_acpi_ec(void)
 	init_waitqueue_head(&ec->wait);
 	INIT_LIST_HEAD(&ec->list);
 	spin_lock_init(&ec->lock);
-	INIT_WORK(&ec->work, acpi_ec_gpe_poller);
+	INIT_WORK(&ec->work, acpi_ec_event_handler);
 	ec->timestamp = jiffies;
 	return ec;
 }
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index cf358d4..ae919b5 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -139,6 +139,7 @@ struct acpi_ec {
 	spinlock_t lock;
 	struct work_struct work;
 	unsigned long timestamp;
+	unsigned long nr_pending_queries;
 };
 
 extern struct acpi_ec *first_ec;
-- 
1.7.10

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/