From 92c6a8d6470f7e7aa86c1f144818d8fa4fcbd5aa Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Mon, 7 Sep 2026 21:01:24 +0900 Subject: [PATCH] dma-mapping: don't trace the DMA address when the allocation fails dma_alloc_attrs() passes *dma_handle to trace_dma_alloc() without checking whether the allocation succeeded. No backend writes it on failure: dma_direct_alloc(), iommu_dma_alloc() and the dma_map_ops instances assign it only on the path that returns a buffer. Callers usually pass an uninitialized automatic variable, so a failed allocation records whatever the stack held, next to the virt_addr=(null) that marks the record as an error: dma_alloc: dmatrace dir=BIDIRECTIONAL dma_addr=deadbeefdeadbeef size=1099511627776 virt_addr=0000000000000000 The device coherent pool path reaches the same call: a non-zero return from dma_alloc_from_dev_coherent() means the request was handled, not that it succeeded, so cpu_addr is NULL and dma_handle is untouched once the pool runs out. For an allocation event a NULL virt_addr already means the request failed, so the address field carries nothing. Report 0 for it in the event class rather than at each call site, which covers dma_alloc_pages() and dma_alloc_sgt_err() as well. Fixes: 038eb433dc14 ("dma-mapping: add tracing for dma-mapping API calls") Fixes: 68b6dbf1f441 ("dma-mapping: trace more error paths") Suggested-by: Marek Szyprowski Signed-off-by: Donggeun Yoo Link: https://lore.kernel.org/r/20260907120124.603373-1-donggeunyoo.kernel@gmail.com Reviewed-by: Sean Anderson Signed-off-by: Marek Szyprowski --- include/trace/events/dma.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/trace/events/dma.h b/include/trace/events/dma.h index 9df02c1511de..b06d8f99922d 100644 --- a/include/trace/events/dma.h +++ b/include/trace/events/dma.h @@ -134,7 +134,7 @@ DECLARE_EVENT_CLASS(dma_alloc_class, TP_fast_assign( __assign_str(device); __entry->virt_addr = virt_addr; - __entry->dma_addr = dma_addr; + __entry->dma_addr = virt_addr ? dma_addr : 0; __entry->size = size; __entry->flags = flags; __entry->dir = dir;