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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 --- 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