Commit de137e44 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

aio-posix: don't duplicate fd handler deletion in fdmon_io_uring_destroy() 



The io_uring file descriptor monitoring implementation has an internal
list of fd handlers that are pending submission to io_uring.
fdmon_io_uring_destroy() deletes all fd handlers on the list.

Don't delete fd handlers directly in fdmon_io_uring_destroy() for two
reasons:
1. This duplicates the aio-posix.c AioHandler deletion code and could
   become outdated if the struct changes.
2. Only handlers with the FDMON_IO_URING_REMOVE flag set are safe to
   remove. If the flag is not set then something still has a pointer to
   the fd handler. Let aio-posix.c and its user worry about that. In
   practice this isn't an issue because fdmon_io_uring_destroy() is only
   called when shutting down so all users have removed their fd
   handlers, but the next patch will need this!

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Tested-by: default avatarOleksandr Natalenko <oleksandr@redhat.com>
Message-id: 20200511183630.279750-2-stefanha@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 6fb5f084

util/aio-posix.c

+1 −0
Original line number Diff line number Diff line
@@ -679,6 +679,7 @@ void aio_context_destroy(AioContext *ctx) 
{

    fdmon_io_uring_destroy(ctx);

    fdmon_epoll_disable(ctx);

    aio_free_deleted_handlers(ctx);

}



void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,

util/fdmon-io_uring.c

+10 −3
Original line number Diff line number Diff line
@@ -342,11 +342,18 @@ void fdmon_io_uring_destroy(AioContext *ctx) 


        io_uring_queue_exit(&ctx->fdmon_io_uring);



        /* No need to submit these anymore, just free them. */

        /* Move handlers due to be removed onto the deleted list */

        while ((node = QSLIST_FIRST_RCU(&ctx->submit_list))) {

            unsigned flags = atomic_fetch_and(&node->flags,

                    ~(FDMON_IO_URING_PENDING |

                      FDMON_IO_URING_ADD |

                      FDMON_IO_URING_REMOVE));



            if (flags & FDMON_IO_URING_REMOVE) {

                QLIST_INSERT_HEAD_RCU(&ctx->deleted_aio_handlers, node, node_deleted);

            }



            QSLIST_REMOVE_HEAD_RCU(&ctx->submit_list, node_submitted);

            QLIST_REMOVE(node, node);

            g_free(node);

        }



        ctx->fdmon_ops = &fdmon_poll_ops;