staging: apf: Add synchronization for DMA-BUF add/remove

DMA-BUF attachment in the APF driver lacked appropriate locking
guarantees. This patch adds those protections to allow for
concurrent attach/detach calls.

Signed-off-by: Michael Gill <gill@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

diff --git a/drivers/staging/apf/xlnk.c b/drivers/staging/apf/xlnk.c
index abbc5d153d6d0c721cfd7a32cef95c426cdc894d..ceeee74ee71a4c644e6903f80ad8eff6a8dcbd8e 100644 (file)
--- a/drivers/staging/apf/xlnk.c
+++ b/drivers/staging/apf/xlnk.c
@@ -881,13 +881,16 @@ static int xlnk_adddmabuf_ioctl(struct file *filp,
        if (status)
                return -ENOMEM;
 
+       spin_lock(&xlnk_buf_lock);
        list_for_each_entry(db, &xlnk_dmabuf_list, list) {
                if (db->user_vaddr == temp_args.dmasubmit.buf) {
                        pr_err("Attempting to register DMA-BUF for addr %llx that is already registered\n",
                               (unsigned long long)temp_args.dmabuf.user_addr);
+                       spin_unlock(&xlnk_buf_lock);
                        return -EINVAL;
                }
        }
+       spin_unlock(&xlnk_buf_lock);
 
        db = kzalloc(sizeof(*db), GFP_KERNEL);
        if (!db)
@@ -913,8 +916,10 @@ static int xlnk_adddmabuf_ioctl(struct file *filp,
                return -EINVAL;
        }
 
+       spin_lock(&xlnk_buf_lock);
        INIT_LIST_HEAD(&db->list);
        list_add_tail(&db->list, &xlnk_dmabuf_list);
+       spin_unlock(&xlnk_buf_lock);
 
        return 0;
 }
@@ -933,6 +938,7 @@ static int xlnk_cleardmabuf_ioctl(struct file *filp,
        if (status)
                return -ENOMEM;
 
+       spin_lock(&xlnk_buf_lock);
        list_for_each_entry_safe(dp, dp_temp, &xlnk_dmabuf_list, list) {
                if (dp->user_vaddr == temp_args.dmabuf.user_addr) {
                        dma_buf_unmap_attachment(dp->dbuf_attach,
@@ -941,10 +947,12 @@ static int xlnk_cleardmabuf_ioctl(struct file *filp,
                        dma_buf_detach(dp->dbuf, dp->dbuf_attach);
                        dma_buf_put(dp->dbuf);
                        list_del(&dp->list);
+                       spin_unlock(&xlnk_buf_lock);
                        kfree(dp);
                        return 0;
                }
        }
+       spin_unlock(&xlnk_buf_lock);
        pr_err("Attempting to unregister a DMA-BUF that was not registered at addr %llx\n",
               (unsigned long long)temp_args.dmabuf.user_addr);