[PATCH v4 18/19] dmaengine: ti: k3-udma: Validate resource ID and fix logging in reservation

[Sai Sree Kartheek Adivi]

The `__udma_reserve_##res` macro currently lacks a bounds check for
the provided `id`. If a caller passes an ID exceeding the resource
count (`ud->res##_cnt`), `test_bit()` performs an out-of-bounds
memory access on the bitmap.

Additionally, the macro returns `-ENOENT` when a resource is already
in use, which is semantically incorrect. The logging logic is also
broken, printing the literal "res##<id>" instead of the resource
name.

Update the macro to:
1. Validate `id` against `ud->res##_cnt` and return `-EINVAL` if out
   of bounds.
2. Return `-EBUSY` instead of `-ENOENT` when a resource is already
   reserved, correctly reflecting the resource state.
3. Use the stringification operator `#res` to correctly print the
   resource name (e.g., "tchan") in error messages.

Signed-off-by: Sai Sree Kartheek Adivi <s-adivi@xxxxxx>
---
 drivers/dma/ti/k3-udma-common.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ti/k3-udma-common.c b/drivers/dma/ti/k3-udma-common.c
index d6459bcc17599..05b2b6b962a06 100644
--- a/drivers/dma/ti/k3-udma-common.c
+++ b/drivers/dma/ti/k3-udma-common.c
@@ -2011,9 +2011,14 @@ struct udma_##res *__udma_reserve_##res(struct udma_dev *ud,	\
 					       int id)			\
 {									\
 	if (id >= 0) {							\
+		if (id >= ud->res##_cnt) {				\
+			dev_err(ud->dev,				\
+				#res " id %d is out of bounds.\n", id);	\
+			return ERR_PTR(-EINVAL);			\
+		}							\
 		if (test_bit(id, ud->res##_map)) {			\
-			dev_err(ud->dev, "res##%d is in use\n", id);	\
-			return ERR_PTR(-ENOENT);			\
+			dev_err(ud->dev, #res "%d is in use\n", id);	\
+			return ERR_PTR(-EBUSY);			\
 		}							\
 	} else {							\
 		int start;						\
-- 
2.34.1