From 4aa1464acbe3697710279a4bd65cb4801ed30425 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 17 Dec 2020 14:29:11 -0800 Subject: [PATCH] spi: spi-geni-qcom: Fix geni_spi_isr() NULL dereference in timeout case In commit 7ba9bdcb91f6 ("spi: spi-geni-qcom: Don't keep a local state variable") we changed handle_fifo_timeout() so that we set "mas->cur_xfer" to NULL to make absolutely sure that we don't mess with the buffers from the previous transfer in the timeout case. Unfortunately, this caused the IRQ handler to dereference NULL in some cases. One case: CPU0 CPU1 ---- ---- setup_fifo_xfer() geni_se_setup_m_cmd() ... handle_fifo_timeout() spin_lock_irq(mas->lock) mas->cur_xfer = NULL geni_se_cancel_m_cmd() spin_unlock_irq(mas->lock) geni_spi_isr() spin_lock(mas->lock) if (m_irq & M_RX_FIFO_WATERMARK_EN) geni_spi_handle_rx() mas->cur_xfer NULL dereference! tl;dr: Seriously delayed interrupts for RX/TX can lead to timeout handling setting mas->cur_xfer to NULL. Let's check for the NULL transfer in the TX and RX cases and reset the watermark or clear out the fifo respectively to put the hardware back into a sane state. NOTE: things still could get confused if we get timeouts all the way through handle_fifo_timeout() and then start a new transfer because interrupts from the old transfer / cancel / abort could still be pending. A future patch will help this corner case. Fixes: 561de45f72bd ("spi: spi-geni-qcom: Add SPI driver support for GENI based QUP") Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd Link: https://lore.kernel.org/r/20201217142842.v3.1.I99ee04f0cb823415df59bd4f550d6ff5756e43d6@changeid Signed-off-by: Mark Brown --- drivers/spi/spi-geni-qcom.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c index 512e925d5ea4..096edfbde451 100644 --- a/drivers/spi/spi-geni-qcom.c +++ b/drivers/spi/spi-geni-qcom.c @@ -354,6 +354,12 @@ static bool geni_spi_handle_tx(struct spi_geni_master *mas) unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas); unsigned int i = 0; + /* Stop the watermark IRQ if nothing to send */ + if (!mas->cur_xfer) { + writel(0, se->base + SE_GENI_TX_WATERMARK_REG); + return false; + } + max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word; if (mas->tx_rem_bytes < max_bytes) max_bytes = mas->tx_rem_bytes; @@ -396,6 +402,14 @@ static void geni_spi_handle_rx(struct spi_geni_master *mas) if (rx_last_byte_valid && rx_last_byte_valid < 4) rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid; } + + /* Clear out the FIFO and bail if nowhere to put it */ + if (!mas->cur_xfer) { + for (i = 0; i < DIV_ROUND_UP(rx_bytes, bytes_per_fifo_word); i++) + readl(se->base + SE_GENI_RX_FIFOn); + return; + } + if (mas->rx_rem_bytes < rx_bytes) rx_bytes = mas->rx_rem_bytes;