On 6/5/20 7:58 AM, Jan Kara wrote:
> Mostly for historical reasons, q->blk_trace is assigned through xchg()
> and cmpxchg() atomic operations. Although this is correct, sparse
> complains about this because it violates rcu annotations since commit
> c780e86dd48e ("blktrace: Protect q->blk_trace with RCU") which started
> to use rcu for accessing q->blk_trace. Furthermore there's no real need
> for atomic operations anymore since all changes to q->blk_trace happen
> under q->blk_trace_mutex and since it also makes more sense to check if
> q->blk_trace is set with the mutex held earlier.
>
> So let's just replace xchg() with rcu_replace_pointer() and cmpxchg()
> with explicit check and rcu_assign_pointer(). This makes the code more
> efficient and sparse happy.
>
> Reported-by: kbuild test robot<lkp@xxxxxxxxx>
> Signed-off-by: Jan Kara<jack@xxxxxxx>
Looks good.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
