[PATCH RFC] net: qca_spi: Fix race condition in spi transfers

From: Stefan Wahren
Date: Fri Aug 03 2018 - 04:06:04 EST

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The performance optimization with the prepared spi messages
also introduced a race condition between the kernel thread
and the register dump. This could make spi_sync hang forever.

So revert the optimization completely.

Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Fixes: 291ab06ecf67 ("net: qualcomm: new Ethernet over SPI driver for QCA7000")
---
drivers/net/ethernet/qualcomm/qca_7k.c | 84 ++++++++++++------------
drivers/net/ethernet/qualcomm/qca_spi.c | 110 +++++++++++++++++---------------
drivers/net/ethernet/qualcomm/qca_spi.h | 5 --
3 files changed, 97 insertions(+), 102 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/qca_7k.c b/drivers/net/ethernet/qualcomm/qca_7k.c
index ffe7a16..e9914b6 100644
--- a/drivers/net/ethernet/qualcomm/qca_7k.c
+++ b/drivers/net/ethernet/qualcomm/qca_7k.c
@@ -43,41 +43,40 @@ qcaspi_spi_error(struct qcaspi *qca)
int
qcaspi_read_register(struct qcaspi *qca, u16 reg, u16 *result)
{
- __be16 rx_data;
__be16 tx_data;
- struct spi_transfer *transfer;
- struct spi_message *msg;
+ struct spi_transfer transfer[2];
+ struct spi_message msg;
int ret;

+ memset(transfer, 0, sizeof(transfer));
+
+ spi_message_init(&msg);
+
tx_data = cpu_to_be16(QCA7K_SPI_READ | QCA7K_SPI_INTERNAL | reg);
+ *result = 0;
+
+ transfer[0].tx_buf = &tx_data;
+ transfer[0].len = QCASPI_CMD_LEN;
+ transfer[1].rx_buf = result;
+ transfer[1].len = QCASPI_CMD_LEN;
+
+ spi_message_add_tail(&transfer[0], &msg);

if (qca->legacy_mode) {
- msg = &qca->spi_msg1;
- transfer = &qca->spi_xfer1;
- transfer->tx_buf = &tx_data;
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- spi_sync(qca->spi_dev, msg);
- } else {
- msg = &qca->spi_msg2;
- transfer = &qca->spi_xfer2[0];
- transfer->tx_buf = &tx_data;
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- transfer = &qca->spi_xfer2[1];
+ spi_sync(qca->spi_dev, &msg);
+ spi_message_init(&msg);
}
- transfer->tx_buf = NULL;
- transfer->rx_buf = &rx_data;
- transfer->len = QCASPI_CMD_LEN;
- ret = spi_sync(qca->spi_dev, msg);
+ spi_message_add_tail(&transfer[1], &msg);
+ ret = spi_sync(qca->spi_dev, &msg);

if (!ret)
- ret = msg->status;
+ ret = msg.status;

- if (ret)
+ if (ret) {
qcaspi_spi_error(qca);
- else
- *result = be16_to_cpu(rx_data);
+ } else {
+ *result = be16_to_cpu(*result);
+ }

return ret;
}
@@ -86,35 +85,32 @@ int
qcaspi_write_register(struct qcaspi *qca, u16 reg, u16 value)
{
__be16 tx_data[2];
- struct spi_transfer *transfer;
- struct spi_message *msg;
+ struct spi_transfer transfer[2];
+ struct spi_message msg;
int ret;

+ memset(&transfer, 0, sizeof(transfer));
+
+ spi_message_init(&msg);
+
tx_data[0] = cpu_to_be16(QCA7K_SPI_WRITE | QCA7K_SPI_INTERNAL | reg);
tx_data[1] = cpu_to_be16(value);

+ transfer[0].tx_buf = &tx_data[0];
+ transfer[0].len = QCASPI_CMD_LEN;
+ transfer[1].tx_buf = &tx_data[1];
+ transfer[1].len = QCASPI_CMD_LEN;
+
+ spi_message_add_tail(&transfer[0], &msg);
if (qca->legacy_mode) {
- msg = &qca->spi_msg1;
- transfer = &qca->spi_xfer1;
- transfer->tx_buf = &tx_data[0];
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- spi_sync(qca->spi_dev, msg);
- } else {
- msg = &qca->spi_msg2;
- transfer = &qca->spi_xfer2[0];
- transfer->tx_buf = &tx_data[0];
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- transfer = &qca->spi_xfer2[1];
+ spi_sync(qca->spi_dev, &msg);
+ spi_message_init(&msg);
}
- transfer->tx_buf = &tx_data[1];
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- ret = spi_sync(qca->spi_dev, msg);
+ spi_message_add_tail(&transfer[1], &msg);
+ ret = spi_sync(qca->spi_dev, &msg);

if (!ret)
- ret = msg->status;
+ ret = msg.status;

if (ret)
qcaspi_spi_error(qca);
diff --git a/drivers/net/ethernet/qualcomm/qca_spi.c b/drivers/net/ethernet/qualcomm/qca_spi.c
index 206f026..66b775d 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.c
+++ b/drivers/net/ethernet/qualcomm/qca_spi.c
@@ -99,22 +99,24 @@ static u32
qcaspi_write_burst(struct qcaspi *qca, u8 *src, u32 len)
{
__be16 cmd;
- struct spi_message *msg = &qca->spi_msg2;
- struct spi_transfer *transfer = &qca->spi_xfer2[0];
+ struct spi_message msg;
+ struct spi_transfer transfer[2];
int ret;

+ memset(&transfer, 0, sizeof(transfer));
+ spi_message_init(&msg);
+
cmd = cpu_to_be16(QCA7K_SPI_WRITE | QCA7K_SPI_EXTERNAL);
- transfer->tx_buf = &cmd;
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- transfer = &qca->spi_xfer2[1];
- transfer->tx_buf = src;
- transfer->rx_buf = NULL;
- transfer->len = len;
+ transfer[0].tx_buf = &cmd;
+ transfer[0].len = QCASPI_CMD_LEN;
+ transfer[1].tx_buf = src;
+ transfer[1].len = len;

- ret = spi_sync(qca->spi_dev, msg);
+ spi_message_add_tail(&transfer[0], &msg);
+ spi_message_add_tail(&transfer[1], &msg);
+ ret = spi_sync(qca->spi_dev, &msg);

- if (ret || (msg->actual_length != QCASPI_CMD_LEN + len)) {
+ if (ret || (msg.actual_length != QCASPI_CMD_LEN + len)) {
qcaspi_spi_error(qca);
return 0;
}
@@ -125,17 +127,20 @@ qcaspi_write_burst(struct qcaspi *qca, u8 *src, u32 len)
static u32
qcaspi_write_legacy(struct qcaspi *qca, u8 *src, u32 len)
{
- struct spi_message *msg = &qca->spi_msg1;
- struct spi_transfer *transfer = &qca->spi_xfer1;
+ struct spi_message msg;
+ struct spi_transfer transfer;
int ret;

- transfer->tx_buf = src;
- transfer->rx_buf = NULL;
- transfer->len = len;
+ memset(&transfer, 0, sizeof(transfer));
+ spi_message_init(&msg);
+
+ transfer.tx_buf = src;
+ transfer.len = len;

- ret = spi_sync(qca->spi_dev, msg);
+ spi_message_add_tail(&transfer, &msg);
+ ret = spi_sync(qca->spi_dev, &msg);

- if (ret || (msg->actual_length != len)) {
+ if (ret || (msg.actual_length != len)) {
qcaspi_spi_error(qca);
return 0;
}
@@ -146,23 +151,25 @@ qcaspi_write_legacy(struct qcaspi *qca, u8 *src, u32 len)
static u32
qcaspi_read_burst(struct qcaspi *qca, u8 *dst, u32 len)
{
- struct spi_message *msg = &qca->spi_msg2;
+ struct spi_message msg;
__be16 cmd;
- struct spi_transfer *transfer = &qca->spi_xfer2[0];
+ struct spi_transfer transfer[2];
int ret;

+ memset(&transfer, 0, sizeof(transfer));
+ spi_message_init(&msg);
+
cmd = cpu_to_be16(QCA7K_SPI_READ | QCA7K_SPI_EXTERNAL);
- transfer->tx_buf = &cmd;
- transfer->rx_buf = NULL;
- transfer->len = QCASPI_CMD_LEN;
- transfer = &qca->spi_xfer2[1];
- transfer->tx_buf = NULL;
- transfer->rx_buf = dst;
- transfer->len = len;
+ transfer[0].tx_buf = &cmd;
+ transfer[0].len = QCASPI_CMD_LEN;
+ transfer[1].rx_buf = dst;
+ transfer[1].len = len;

- ret = spi_sync(qca->spi_dev, msg);
+ spi_message_add_tail(&transfer[0], &msg);
+ spi_message_add_tail(&transfer[1], &msg);
+ ret = spi_sync(qca->spi_dev, &msg);

- if (ret || (msg->actual_length != QCASPI_CMD_LEN + len)) {
+ if (ret || (msg.actual_length != QCASPI_CMD_LEN + len)) {
qcaspi_spi_error(qca);
return 0;
}
@@ -173,17 +180,20 @@ qcaspi_read_burst(struct qcaspi *qca, u8 *dst, u32 len)
static u32
qcaspi_read_legacy(struct qcaspi *qca, u8 *dst, u32 len)
{
- struct spi_message *msg = &qca->spi_msg1;
- struct spi_transfer *transfer = &qca->spi_xfer1;
+ struct spi_message msg;
+ struct spi_transfer transfer;
int ret;

- transfer->tx_buf = NULL;
- transfer->rx_buf = dst;
- transfer->len = len;
+ memset(&transfer, 0, sizeof(transfer));
+ spi_message_init(&msg);

- ret = spi_sync(qca->spi_dev, msg);
+ transfer.rx_buf = dst;
+ transfer.len = len;

- if (ret || (msg->actual_length != len)) {
+ spi_message_add_tail(&transfer, &msg);
+ ret = spi_sync(qca->spi_dev, &msg);
+
+ if (ret || (msg.actual_length != len)) {
qcaspi_spi_error(qca);
return 0;
}
@@ -195,19 +205,23 @@ static int
qcaspi_tx_cmd(struct qcaspi *qca, u16 cmd)
{
__be16 tx_data;
- struct spi_message *msg = &qca->spi_msg1;
- struct spi_transfer *transfer = &qca->spi_xfer1;
+ struct spi_message msg;
+ struct spi_transfer transfer;
int ret;

+ memset(&transfer, 0, sizeof(transfer));
+
+ spi_message_init(&msg);
+
tx_data = cpu_to_be16(cmd);
- transfer->len = sizeof(tx_data);
- transfer->tx_buf = &tx_data;
- transfer->rx_buf = NULL;
+ transfer.len = sizeof(cmd);
+ transfer.tx_buf = &tx_data;
+ spi_message_add_tail(&transfer, &msg);

- ret = spi_sync(qca->spi_dev, msg);
+ ret = spi_sync(qca->spi_dev, &msg);

if (!ret)
- ret = msg->status;
+ ret = msg.status;

if (ret)
qcaspi_spi_error(qca);
@@ -835,16 +849,6 @@ qcaspi_netdev_setup(struct net_device *dev)
qca = netdev_priv(dev);
memset(qca, 0, sizeof(struct qcaspi));

- memset(&qca->spi_xfer1, 0, sizeof(struct spi_transfer));
- memset(&qca->spi_xfer2, 0, sizeof(struct spi_transfer) * 2);
-
- spi_message_init(&qca->spi_msg1);
- spi_message_add_tail(&qca->spi_xfer1, &qca->spi_msg1);
-
- spi_message_init(&qca->spi_msg2);
- spi_message_add_tail(&qca->spi_xfer2[0], &qca->spi_msg2);
- spi_message_add_tail(&qca->spi_xfer2[1], &qca->spi_msg2);
-
memset(&qca->txr, 0, sizeof(qca->txr));
qca->txr.count = TX_RING_MAX_LEN;
}
diff --git a/drivers/net/ethernet/qualcomm/qca_spi.h b/drivers/net/ethernet/qualcomm/qca_spi.h
index fc4beb1..fc0e987 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.h
+++ b/drivers/net/ethernet/qualcomm/qca_spi.h
@@ -83,11 +83,6 @@ struct qcaspi {
struct tx_ring txr;
struct qcaspi_stats stats;

- struct spi_message spi_msg1;
- struct spi_message spi_msg2;
- struct spi_transfer spi_xfer1;
- struct spi_transfer spi_xfer2[2];
-
u8 *rx_buffer;
u32 buffer_size;
u8 sync;
--
2.7.4

Next message: Matti Vaittinen: "Re: [PATCH v5 4/4] clk: bd71837: Add driver for BD71837 PMIC clock"
Previous message: Baolin Wang: "Re: [PATCH v2 1/2] leds: core: Introduce LED pattern trigger"
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