linux-kernel - [PATCH 04/17] firewire: ohci: use guard macro to serialize accesses to phy registers

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Message-ID: <20240804130225.243496-5-o-takashi@sakamocchi.jp>
Date: Sun,  4 Aug 2024 22:02:11 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 04/17] firewire: ohci: use guard macro to serialize accesses to phy registers

The 1394 OHCI driver protects concurrent accesses to phy registers by
mutex object in fw_ohci structure.

This commit uses guard macro to maintain the mutex.

Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
 drivers/firewire/ohci.c | 71 +++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 35 deletions(-)

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 8f2bbd0569fb..1461e008d265 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -713,26 +713,20 @@ static int read_paged_phy_reg(struct fw_ohci *ohci, int page, int addr)
 static int ohci_read_phy_reg(struct fw_card *card, int addr)
 {
 	struct fw_ohci *ohci = fw_ohci(card);
-	int ret;
 
-	mutex_lock(&ohci->phy_reg_mutex);
-	ret = read_phy_reg(ohci, addr);
-	mutex_unlock(&ohci->phy_reg_mutex);
+	guard(mutex)(&ohci->phy_reg_mutex);
 
-	return ret;
+	return read_phy_reg(ohci, addr);
 }
 
 static int ohci_update_phy_reg(struct fw_card *card, int addr,
 			       int clear_bits, int set_bits)
 {
 	struct fw_ohci *ohci = fw_ohci(card);
-	int ret;
 
-	mutex_lock(&ohci->phy_reg_mutex);
-	ret = update_phy_reg(ohci, addr, clear_bits, set_bits);
-	mutex_unlock(&ohci->phy_reg_mutex);
+	guard(mutex)(&ohci->phy_reg_mutex);
 
-	return ret;
+	return update_phy_reg(ohci, addr, clear_bits, set_bits);
 }
 
 static inline dma_addr_t ar_buffer_bus(struct ar_context *ctx, unsigned int i)
@@ -1882,13 +1876,15 @@ static int get_status_for_port(struct fw_ohci *ohci, int port_index,
 {
 	int reg;
 
-	mutex_lock(&ohci->phy_reg_mutex);
-	reg = write_phy_reg(ohci, 7, port_index);
-	if (reg >= 0)
+	scoped_guard(mutex, &ohci->phy_reg_mutex) {
+		reg = write_phy_reg(ohci, 7, port_index);
+		if (reg < 0)
+			return reg;
+
 		reg = read_phy_reg(ohci, 8);
-	mutex_unlock(&ohci->phy_reg_mutex);
-	if (reg < 0)
-		return reg;
+		if (reg < 0)
+			return reg;
+	}
 
 	switch (reg & 0x0f) {
 	case 0x06:
@@ -1929,26 +1925,31 @@ static int get_self_id_pos(struct fw_ohci *ohci, u32 self_id,
 static bool initiated_reset(struct fw_ohci *ohci)
 {
 	int reg;
-	int ret = false;
 
-	mutex_lock(&ohci->phy_reg_mutex);
-	reg = write_phy_reg(ohci, 7, 0xe0); /* Select page 7 */
-	if (reg >= 0) {
-		reg = read_phy_reg(ohci, 8);
-		reg |= 0x40;
-		reg = write_phy_reg(ohci, 8, reg); /* set PMODE bit */
-		if (reg >= 0) {
-			reg = read_phy_reg(ohci, 12); /* read register 12 */
-			if (reg >= 0) {
-				if ((reg & 0x08) == 0x08) {
-					/* bit 3 indicates "initiated reset" */
-					ret = true;
-				}
-			}
-		}
-	}
-	mutex_unlock(&ohci->phy_reg_mutex);
-	return ret;
+	guard(mutex)(&ohci->phy_reg_mutex);
+
+	// Select page 7
+	reg = write_phy_reg(ohci, 7, 0xe0);
+	if (reg < 0)
+		return reg;
+
+	reg = read_phy_reg(ohci, 8);
+	if (reg < 0)
+		return reg;
+
+	// set PMODE bit
+	reg |= 0x40;
+	reg = write_phy_reg(ohci, 8, reg);
+	if (reg < 0)
+		return reg;
+
+	// read register 12
+	reg = read_phy_reg(ohci, 12);
+	if (reg < 0)
+		return reg;
+
+	// bit 3 indicates "initiated reset"
+	return !!((reg & 0x08) == 0x08);
 }
 
 /*
-- 
2.43.0