linux-kernel - [PATCH v3 2/3] firmware_class: Drop bit ops in favor of simple state machine

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Date:   Thu, 25 Aug 2016 11:52:02 +0200
From:   Daniel Wagner <wagi@...om.org>
To:     linux-kernel@...r.kernel.org
Cc:     Daniel Wagner <daniel.wagner@...-carit.de>,
        Ming Lei <ming.lei@...onical.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v3 2/3] firmware_class: Drop bit ops in favor of simple state machine

From: Daniel Wagner <daniel.wagner@...-carit.de>

We track the state of the loading with bit ops. Since the state machine
has only a couple of states and there are only a few simple state
transition we can model this simplify.

	   UNKNOWN -> LOADING -> DONE | ABORTED

Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Cc: Ming Lei <ming.lei@...onical.com>
Cc: Luis R. Rodriguez <mcgrof@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/base/firmware_class.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index f397026..d6cb33a 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -120,16 +120,18 @@ static void fw_status_init(struct fw_status *fw_st)
 
 static int __fw_status_check(struct fw_status *fw_st, unsigned long status)
 {
-	return test_bit(status, &fw_st->status);
+	return fw_st->status == status;
 }
 
 static int fw_status_wait_timeout(struct fw_status *fw_st, long timeout)
 {
+	unsigned long status;
 	int ret;
 
 	ret = wait_for_completion_interruptible_timeout(&fw_st->completion,
 							timeout);
-	if (ret == 0 && test_bit(FW_STATUS_ABORTED, &fw_st->status))
+	status = READ_ONCE(fw_st->status);
+	if (ret == 0 && status == FW_STATUS_ABORTED)
 		return -ENOENT;
 
 	return ret;
@@ -138,13 +140,11 @@ static int fw_status_wait_timeout(struct fw_status *fw_st, long timeout)
 static void __fw_status_set(struct fw_status *fw_st,
 			  unsigned long status)
 {
-	set_bit(status, &fw_st->status);
+	WRITE_ONCE(fw_st->status, status);
 
 	if (status == FW_STATUS_DONE ||
-			status == FW_STATUS_ABORTED) {
-		clear_bit(FW_STATUS_LOADING, &fw_st->status);
+			status == FW_STATUS_ABORTED)
 		complete_all(&fw_st->completion);
-	}
 }
 
 #define fw_status_start(fw_st)					\
-- 
2.7.4