io_uring: clean __io_import_iovec()

Apparently, implicit 0 to NULL conversion with ERR_PTR is not
recommended and makes some tooling like Smatch to complain. Handle it
explicitly, compilers are perfectly capable to optimise it out.

Link: https://lore.kernel.org/all/20211108134937.GA2863@kili/
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5c6ed369ad95075dab345df679f8677b8fe66656.1637524285.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7ef2d0c1296fc57298d5afdf9b59f2742038e950..a65fb9cd9db7344f11864c7477439a6f0d3a2122 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3179,10 +3179,12 @@ static struct iovec *__io_import_iovec(int rw, struct io_kiocb *req,
        size_t sqe_len;
        ssize_t ret;
 
-       BUILD_BUG_ON(ERR_PTR(0) != NULL);
-
-       if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED)
-               return ERR_PTR(io_import_fixed(req, rw, iter));
+       if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
+               ret = io_import_fixed(req, rw, iter);
+               if (ret)
+                       return ERR_PTR(ret);
+               return NULL;
+       }
 
        /* buffer index only valid with fixed read/write, or buffer select  */
        if (unlikely(req->buf_index && !(req->flags & REQ_F_BUFFER_SELECT)))
@@ -3200,15 +3202,18 @@ static struct iovec *__io_import_iovec(int rw, struct io_kiocb *req,
                }
 
                ret = import_single_range(rw, buf, sqe_len, s->fast_iov, iter);
-               return ERR_PTR(ret);
+               if (ret)
+                       return ERR_PTR(ret);
+               return NULL;
        }
 
        iovec = s->fast_iov;
        if (req->flags & REQ_F_BUFFER_SELECT) {
                ret = io_iov_buffer_select(req, iovec, issue_flags);
-               if (!ret)
-                       iov_iter_init(iter, rw, iovec, 1, iovec->iov_len);
-               return ERR_PTR(ret);
+               if (ret)
+                       return ERR_PTR(ret);
+               iov_iter_init(iter, rw, iovec, 1, iovec->iov_len);
+               return NULL;
        }
 
        ret = __import_iovec(rw, buf, sqe_len, UIO_FASTIOV, &iovec, iter,