linux-kernel - [PATCH v5 4/5] firmware: drop bit ops in favor of simple state machine

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Date:   Fri,  9 Sep 2016 14:12:23 +0200
From:   Daniel Wagner <wagi@...om.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ming Lei <ming.lei@...onical.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Srivatsa S . Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
        "Rafael J . Wysocki" <rjw@...k.pl>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Takashi Iwai <tiwai@...e.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Arend van Spriel <arend.vanspriel@...adcom.com>,
        Daniel Wagner <daniel.wagner@...-carit.de>
Subject: [PATCH v5 4/5] firmware: 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 they are all mutual exclusive there are
only a few simple state transition we can model this simplify.

	   UNKNOWN -> LOADING -> DONE | ABORTED

Cc: Ming Lei <ming.lei@...onical.com>
Cc: Luis R. Rodriguez <mcgrof@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
---
 drivers/base/firmware_class.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 5e38c27..8f5838c 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -109,7 +109,7 @@ enum {
 
 struct fw_umh {
 	struct completion completion;
-	unsigned long status;
+	u8 status;
 };
 
 static void fw_umh_init(struct fw_umh *fw_umh)
@@ -120,7 +120,7 @@ static void fw_umh_init(struct fw_umh *fw_umh)
 
 static int __fw_umh_check(struct fw_umh *fw_umh, unsigned long status)
 {
-	return test_bit(status, &fw_umh->status);
+	return fw_umh->status == status;
 }
 
 static int fw_umh_wait_timeout(struct fw_umh *fw_umh, long timeout)
@@ -129,7 +129,7 @@ static int fw_umh_wait_timeout(struct fw_umh *fw_umh, long timeout)
 
 	ret = wait_for_completion_interruptible_timeout(&fw_umh->completion,
 							timeout);
-	if (ret != 0 && test_bit(FW_UMH_ABORTED, &fw_umh->status))
+	if (ret != 0 && READ_ONCE(fw_umh->status) == FW_UMH_ABORTED)
 		return -ENOENT;
 
 	return ret;
@@ -138,12 +138,10 @@ static int fw_umh_wait_timeout(struct fw_umh *fw_umh, long timeout)
 static void __fw_umh_set(struct fw_umh *fw_umh,
 			  unsigned long status)
 {
-	set_bit(status, &fw_umh->status);
+	WRITE_ONCE(fw_umh->status, status);
 
-	if (status == FW_UMH_DONE || status == FW_UMH_ABORTED) {
-		clear_bit(FW_UMH_LOADING, &fw_umh->status);
+	if (status == FW_UMH_DONE || status == FW_UMH_ABORTED)
 		complete_all(&fw_umh->completion);
-	}
 }
 
 #define fw_umh_start(fw_umh)					\
-- 
2.7.4