[PATCH v4 3/4] ublk: mark ublk_queue as const for ublk_register_io_buf

[Uday Shankar]

We now allow multiple tasks to operate on I/Os belonging to the same
queue concurrently. This means that any writes to ublk_queue in the I/O
path are potential sources of data races. Try to prevent these by
marking ublk_queue pointers as const in ublk_register_io_buf.

Suggested-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Uday Shankar <ushankar@xxxxxxxxxxxxxxx>
---
 drivers/block/ublk_drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 153f67d92248ad45bddd2437b1306bb23df7d1ae..e2cb54895481aebaa91ab23ba05cf26a950a642f 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -211,7 +211,7 @@ struct ublk_params_header {
 static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq);
 
 static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
-		struct ublk_queue *ubq, int tag, size_t offset);
+		const struct ublk_queue *ubq, int tag, size_t offset);
 static inline unsigned int ublk_req_build_flags(struct request *req);
 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 						   int tag);
@@ -1867,7 +1867,7 @@ static void ublk_io_release(void *priv)
 }
 
 static int ublk_register_io_buf(struct io_uring_cmd *cmd,
-				struct ublk_queue *ubq, unsigned int tag,
+				const struct ublk_queue *ubq, unsigned int tag,
 				unsigned int index, unsigned int issue_flags)
 {
 	struct ublk_device *ub = cmd->file->private_data;
@@ -2043,7 +2043,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
 }
 
 static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
-		struct ublk_queue *ubq, int tag, size_t offset)
+		const struct ublk_queue *ubq, int tag, size_t offset)
 {
 	struct request *req;
 

-- 
2.34.1