[PATCH v2 3/4] soundwire: cadence: use directly bus sdw_defer structure

[Bard Liao <yung-chuan.liao@linux.intel.com>]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Copying the bus sdw_defer structure into the Cadence internals leads
to using stale pointers and kernel oopses on errors. It's just simpler
and safer to use the bus sdw_defer structure directly.

Link: https://github.com/thesofproject/linux/issues/4056
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 drivers/soundwire/bus.c            |  2 +-
 drivers/soundwire/cadence_master.c | 17 ++++++++---------
 drivers/soundwire/cadence_master.h |  5 +----
 include/linux/soundwire/sdw.h      |  3 +--
 4 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 572cc9a9af41..fc192d0c61e7 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -237,7 +237,7 @@ static inline int do_transfer_defer(struct sdw_bus *bus,
 	init_completion(&defer->complete);
 
 	for (i = 0; i <= retry; i++) {
-		resp = bus->ops->xfer_msg_defer(bus, msg, defer);
+		resp = bus->ops->xfer_msg_defer(bus, msg);
 		ret = find_response_code(resp);
 		/* if cmd is ok or ignored return */
 		if (ret == 0 || ret == -ENODATA)
diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 521387322145..2365395cb181 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -750,7 +750,7 @@ EXPORT_SYMBOL(cdns_xfer_msg);
 
 enum sdw_command_response
 cdns_xfer_msg_defer(struct sdw_bus *bus,
-		    struct sdw_msg *msg, struct sdw_defer *defer)
+		    struct sdw_msg *msg)
 {
 	struct sdw_cdns *cdns = bus_to_cdns(bus);
 	int cmd = 0, ret;
@@ -763,9 +763,6 @@ cdns_xfer_msg_defer(struct sdw_bus *bus,
 	if (ret)
 		return SDW_CMD_FAIL_OTHER;
 
-	cdns->defer = defer;
-	cdns->defer->length = msg->len;
-
 	return _cdns_xfer_msg(cdns, msg, cmd, 0, msg->len, true);
 }
 EXPORT_SYMBOL(cdns_xfer_msg_defer);
@@ -893,13 +890,15 @@ irqreturn_t sdw_cdns_irq(int irq, void *dev_id)
 		return IRQ_NONE;
 
 	if (int_status & CDNS_MCP_INT_RX_WL) {
+		struct sdw_bus *bus = &cdns->bus;
+		struct sdw_defer *defer = &bus->defer_msg;
+
 		cdns_read_response(cdns);
 
-		if (cdns->defer) {
-			cdns_fill_msg_resp(cdns, cdns->defer->msg,
-					   cdns->defer->length, 0);
-			complete(&cdns->defer->complete);
-			cdns->defer = NULL;
+		if (defer && defer->msg) {
+			cdns_fill_msg_resp(cdns, defer->msg,
+					   defer->length, 0);
+			complete(&defer->complete);
 		} else {
 			complete(&cdns->tx_complete);
 		}
diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
index fa9dc38264a4..53029d22822d 100644
--- a/drivers/soundwire/cadence_master.h
+++ b/drivers/soundwire/cadence_master.h
@@ -109,7 +109,6 @@ struct sdw_cdns_dai_runtime {
  * @instance: instance number
  * @response_buf: SoundWire response buffer
  * @tx_complete: Tx completion
- * @defer: Defer pointer
  * @ports: Data ports
  * @num_ports: Total number of data ports
  * @pcm: PCM streams
@@ -130,7 +129,6 @@ struct sdw_cdns {
 	u32 response_buf[CDNS_MCP_IP_MAX_CMD_LEN + 2];
 
 	struct completion tx_complete;
-	struct sdw_defer *defer;
 
 	struct sdw_cdns_port *ports;
 	int num_ports;
@@ -189,8 +187,7 @@ enum sdw_command_response
 cdns_xfer_msg(struct sdw_bus *bus, struct sdw_msg *msg);
 
 enum sdw_command_response
-cdns_xfer_msg_defer(struct sdw_bus *bus,
-		    struct sdw_msg *msg, struct sdw_defer *defer);
+cdns_xfer_msg_defer(struct sdw_bus *bus, struct sdw_msg *msg);
 
 u32 cdns_read_ping_status(struct sdw_bus *bus);
 
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 3cd2a761911f..fb2bd1524a26 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -852,8 +852,7 @@ struct sdw_master_ops {
 	enum sdw_command_response (*xfer_msg)
 			(struct sdw_bus *bus, struct sdw_msg *msg);
 	enum sdw_command_response (*xfer_msg_defer)
-			(struct sdw_bus *bus, struct sdw_msg *msg,
-			struct sdw_defer *defer);
+			(struct sdw_bus *bus, struct sdw_msg *msg);
 	enum sdw_command_response (*reset_page_addr)
 			(struct sdw_bus *bus, unsigned int dev_num);
 	int (*set_bus_conf)(struct sdw_bus *bus,
-- 
2.25.1