[PATCH v2 2/6] spi: tegra210-quad: Move curr_xfer read inside spinlock

[Breno Leitao <leitao@debian.org>]

Move the assignment of the transfer pointer from curr_xfer inside the
spinlock critical section in both handle_cpu_based_xfer() and
handle_dma_based_xfer().

Previously, curr_xfer was read before acquiring the lock, creating a
window where the timeout path could clear curr_xfer between reading it
and using it. By moving the read inside the lock, the handlers are
guaranteed to see a consistent value that cannot be modified by the
timeout path.

Fixes: 921fc1838fb0 ("spi: tegra210-quad: Add support for Tegra210 QSPI controller")
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/spi/spi-tegra210-quad.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
index f0408c0b4b981..ee291b9e9e9c0 100644
--- a/drivers/spi/spi-tegra210-quad.c
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -1440,10 +1440,11 @@ static int tegra_qspi_transfer_one_message(struct spi_controller *host,
 
 static irqreturn_t handle_cpu_based_xfer(struct tegra_qspi *tqspi)
 {
-	struct spi_transfer *t = tqspi->curr_xfer;
+	struct spi_transfer *t;
 	unsigned long flags;
 
 	spin_lock_irqsave(&tqspi->lock, flags);
+	t = tqspi->curr_xfer;
 
 	if (tqspi->tx_status ||  tqspi->rx_status) {
 		tegra_qspi_handle_error(tqspi);
@@ -1474,7 +1475,7 @@ static irqreturn_t handle_cpu_based_xfer(struct tegra_qspi *tqspi)
 
 static irqreturn_t handle_dma_based_xfer(struct tegra_qspi *tqspi)
 {
-	struct spi_transfer *t = tqspi->curr_xfer;
+	struct spi_transfer *t;
 	unsigned int total_fifo_words;
 	unsigned long flags;
 	long wait_status;
@@ -1513,6 +1514,7 @@ static irqreturn_t handle_dma_based_xfer(struct tegra_qspi *tqspi)
 	}
 
 	spin_lock_irqsave(&tqspi->lock, flags);
+	t = tqspi->curr_xfer;
 
 	if (num_errors) {
 		tegra_qspi_dma_unmap_xfer(tqspi, t);

-- 
2.47.3