i3c: mipi-i3c-hci: Mask ring interrupts before ring stop request

Bus cleanup path in DMA mode may trigger a RING_OP_STAT interrupt when
the ring is being stopped. Depending on timing between ring stop request
completion, interrupt handler removal and code execution this may lead
to a NULL pointer dereference in hci_dma_irq_handler() if it gets to run
after the io_data pointer is set to NULL in hci_dma_cleanup().

Prevent this my masking the ring interrupts before ring stop request.

Signed-off-by: Jarkko Nikula <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

Author: jhnikula

drivers/i3c/master/mipi-i3c-hci/dma.c

@@ -159,10 +159,10 @@ static void hci_dma_cleanup(struct i3c_hci *hci)
 	for (i = 0; i < rings->total; i++) {
 		rh = &rings->headers[i];
 
+		rh_reg_write(INTR_SIGNAL_ENABLE, 0);
 		rh_reg_write(RING_CONTROL, 0);
 		rh_reg_write(CR_SETUP, 0);
 		rh_reg_write(IBI_SETUP, 0);
-		rh_reg_write(INTR_SIGNAL_ENABLE, 0);
 
 		if (rh->xfer)
 			dma_free_coherent(&hci->master.dev,