[PATCH v2] USB: mtu3: tracing: fix pointers dereferencing

[Marek Szyprowski]

Commit b5cc230af5e5 ("tracing: Warn when an event dereferences a pointer
in TP_printk()") added a warning when printing an event dereferences
a pointer, because it might be already freed at that time.

MTU3 driver is one of the drivers triggering this warning. Fix it by
storing the DMA address in the event structure to avoid dereferencing
gpd_ring pointer during event printing.

Fixes: 83374e035b62 ("usb: mtu3: add tracepoints to help debug")
Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
v2:
- fixed typos in commit description

v1: https://lore.kernel.org/all/20260804100531.88576-1-m.szyprowski@xxxxxxxxxxx/
---
 drivers/usb/mtu3/mtu3_trace.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h
index 89870175d635..b24c6411a8cf 100644
--- a/drivers/usb/mtu3/mtu3_trace.h
+++ b/drivers/usb/mtu3/mtu3_trace.h
@@ -224,6 +224,7 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
 		__field(unsigned int, flags)
 		__field(unsigned int, direction)
 		__field(struct mtu3_gpd_ring *, gpd_ring)
+		__field(dma_addr_t, gpd_ring_dma)
 	),
 	TP_fast_assign(
 		__assign_str(name);
@@ -235,12 +236,13 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
 		__entry->flags = mep->flags;
 		__entry->direction = mep->is_in;
 		__entry->gpd_ring = &mep->gpd_ring;
+		__entry->gpd_ring_dma = __entry->gpd_ring->dma;
 	),
 	TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c",
 		__get_str(name), usb_ep_type_string(__entry->type),
 		__entry->maxp, __entry->slot,
 		__entry->mult, __entry->maxburst,
-		__entry->gpd_ring, &__entry->gpd_ring->dma,
+		__entry->gpd_ring, &__entry->gpd_ring_dma,
 		__entry->flags & MTU3_EP_ENABLED ? 'E' : 'e',
 		__entry->flags & MTU3_EP_STALL ? 'S' : 's',
 		__entry->flags & MTU3_EP_WEDGE ? 'W' : 'w',
-- 
2.43.0