Hello Jens Axboe,
The patch f67676d160c6: "io_uring: ensure async punted read/write
requests copy iovec" from Dec 2, 2019, leads to the following static
checker warning:
fs/io_uring.c:2919 io_req_defer()
warn: inconsistent returns 'irq'.
fs/io_uring.c
2891 static int io_req_defer(struct io_kiocb *req)
2892 {
2893 struct io_ring_ctx *ctx = req->ctx;
2894 struct io_async_ctx *io;
2895 int ret;
2896
2897 /* Still need defer if there is pending req in defer list. */
2898 if (!req_need_defer(req) && list_empty(&ctx->defer_list))
2899 return 0;
2900
2901 io = kmalloc(sizeof(*io), GFP_KERNEL);
2902 if (!io)
2903 return -EAGAIN;
2904
2905 spin_lock_irq(&ctx->completion_lock);
2906 if (!req_need_defer(req) && list_empty(&ctx->defer_list)) {
2907 spin_unlock_irq(&ctx->completion_lock);
2908 kfree(io);
2909 return 0;
2910 }
2911
2912 ret = io_req_defer_prep(req, io);
2913 if (ret < 0)
2914 return ret;
We need to spin_unlock_irq(&ctx->completion_lock); before returning.
The question of if we need to kfree(io) is more complicated to me
because I'm not sure how kiocb->ki_complete gets called...
2915
2916 trace_io_uring_defer(ctx, req, req->user_data);
2917 list_add_tail(&req->list, &ctx->defer_list);
2918 spin_unlock_irq(&ctx->completion_lock);
2919 return -EIOCBQUEUED;
2920 }
regards,
dan carpenter
