spi: topcliff-pch: fix use-after-free on unbind

commit 9d72732 upstream.

Give the driver a chance to flush its queue before releasing the DMA
buffers on driver unbind

Fixes: c37f3c2 ("spi/topcliff_pch: DMA support")
Cc: stable@vger.kernel.org	# 3.1
Cc: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20260414134319.978196-9-johan@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/spi/spi-topcliff-pch.c

@@ -1406,9 +1406,6 @@ static void pch_spi_pd_remove(struct platform_device *plat_dev)
 	dev_dbg(&plat_dev->dev, "%s:[ch%d] irq=%d\n",
 		__func__, plat_dev->id, board_dat->pdev->irq);
 
-	if (use_dma)
-		pch_free_dma_buf(board_dat, data);
-
 	/* check for any pending messages; no action is taken if the queue
 	 * is still full; but at least we tried.  Unload anyway */
 	count = 500;
@@ -1432,6 +1429,9 @@ static void pch_spi_pd_remove(struct platform_device *plat_dev)
 		free_irq(board_dat->pdev->irq, data);
 	}
 
+	if (use_dma)
+		pch_free_dma_buf(board_dat, data);
+
 	pci_iounmap(board_dat->pdev, data->io_remap_addr);
 	spi_unregister_master(data->master);
 }