[PATCH] staging: vme_user: vme_bridge.h: Document mutex in vme_dma_resource structure

[Riyan Dhiman]

Adhere to Linux kernel coding style

Reported by checkpatch:

CHECK: mutex definition without comment

Proof for comment:

1. The mutex is used to protect access to the 'running' list
(line 1798 tsi148_dma_list_exec function)
        mutex_lock(&ctrlrl->mtx);
        if (!list_empty(&ctrlr->running)) {
                mutex_unlock(&ctrlr->mtx);
                return -EBUSY;
        }
  This prevents race conditions when multiple threads attempt to start DMA
  operations simultaneously.

2. It's also used when removing DMA list from running list:
(line 1862 tsi148_dma_list_exec function)
        mutex_lock(&ctrlr->mtx);
        list_del(&list->list);
        mutex_unlock(&ctrlr->mtx);
  Ensuring thread-safe modification of the controller's state.

Without this mutex, concurrent access to the DMA controller's state could
lead to data corruption or inconsistant state.

Signed-off-by: Riyan Dhiman <riyandhima...@gmail.com>
---
 drivers/staging/vme_user/vme_bridge.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/staging/vme_user/vme_bridge.h 
b/drivers/staging/vme_user/vme_bridge.h
index 9bdc41bb6602..bb3750b40eb1 100644
--- a/drivers/staging/vme_user/vme_bridge.h
+++ b/drivers/staging/vme_user/vme_bridge.h
@@ -61,6 +61,7 @@ struct vme_dma_list {
 struct vme_dma_resource {
        struct list_head list;
        struct vme_bridge *parent;
+       /* Mutex to protect DMA controller resources and ensure thread-safe 
operations */
        struct mutex mtx;
        int locked;
        int number;
-- 
2.39.2