From 73e5616f3d197c1af5a04a481fe0f13aa3913bd1 Mon Sep 17 00:00:00 2001 From: Edwin Peer Date: Wed, 9 Sep 2026 13:23:27 -0700 Subject: [PATCH] rust: dma_fence: gate abstractions on CONFIG_DMA_SHARED_BUFFER The dma_fence abstractions added by commit 3282d5916019 ("rust: Add dma_fence abstractions") are compiled unconditionally, but the C `dma_fence_*` symbols they reference live in drivers/dma-buf/dma-fence.c, which is only built when CONFIG_DMA_SHARED_BUFFER=y. Kernels with CONFIG_RUST=y and CONFIG_RUST_KERNEL_DOCTESTS=y but CONFIG_DMA_SHARED_BUFFER=n fail to link: ld.lld: error: undefined symbol: dma_fence_release >>> referenced by usercopy_64.c >>> vmlinux.o:(rust_helper_dma_fence_put) ... dma_fence_signal{,_locked}, dma_fence_context_alloc, dma_fence_init, dma_fence_{add,remove}_callback ... Wrap the dma_fence.c helper include in the same `pub mod dma_buf;` in rust/kernel/lib.rs with a matching #[cfg]. Fixes: 3282d5916019 ("rust: Add dma_fence abstractions") Signed-off-by: Edwin Peer Reviewed-by: John Hubbard Reviewed-by: Philipp Stanner Link: https://patch.msgid.link/20260909202327.33285-1-epeer@nvidia.com Signed-off-by: Danilo Krummrich --- rust/helpers/helpers.c | 2 +- rust/kernel/lib.rs | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 609689fba3dd..2c5eecc091c4 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -57,8 +57,8 @@ #include "cred.c" #include "device.c" #include "dma.c" -#include "dma_fence.c" #ifdef CONFIG_DMA_SHARED_BUFFER +#include "dma_fence.c" #include "dma-resv.c" #endif #include "drm.c" diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 72f5527ba66c..f9ef36217bb5 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -67,6 +67,7 @@ pub mod device_id; pub mod devres; pub mod dma; +#[cfg(CONFIG_DMA_SHARED_BUFFER)] pub mod dma_buf; pub mod driver; #[cfg(CONFIG_DRM = "y")]