Re: [Qemu-devel] [PATCH 06/12] linux-aio: use event notifiers

[Anthony Liguori <anthony@codemonkey.ws>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> Since linux-aio already uses an eventfd, converting it to use the
> EventNotifier-based API simplifies the code even though it is not
> meant to be portable.
>

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

Regards,

Anthony Liguori

> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  linux-aio.c |   49 +++++++++++++++++++------------------------------
>  1 file changed, 19 insertions(+), 30 deletions(-)
>
> diff --git a/linux-aio.c b/linux-aio.c
> index fa0fbf3..779f793 100644
> --- a/linux-aio.c
> +++ b/linux-aio.c
> @@ -10,8 +10,8 @@
>  #include "qemu-common.h"
>  #include "qemu-aio.h"
>  #include "block/raw-posix-aio.h"
> +#include "event_notifier.h"
>  
> -#include <sys/eventfd.h>
>  #include <libaio.h>
>  
>  /*
> @@ -37,7 +37,7 @@ struct qemu_laiocb {
>  
>  struct qemu_laio_state {
>      io_context_t ctx;
> -    int efd;
> +    EventNotifier e;
>      int count;
>  };
>  
> @@ -76,29 +76,17 @@ static void qemu_laio_process_completion(struct qemu_laio_state *s,
>      qemu_aio_release(laiocb);
>  }
>  
> -static void qemu_laio_completion_cb(void *opaque)
> +static void qemu_laio_completion_cb(EventNotifier *e)
>  {
> -    struct qemu_laio_state *s = opaque;
> +    struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
>  
> -    while (1) {
> +    while (event_notifier_test_and_clear(&s->e)) {
>          struct io_event events[MAX_EVENTS];
> -        uint64_t val;
> -        ssize_t ret;
>          struct timespec ts = { 0 };
>          int nevents, i;
>  
>          do {
> -            ret = read(s->efd, &val, sizeof(val));
> -        } while (ret == -1 && errno == EINTR);
> -
> -        if (ret == -1 && errno == EAGAIN)
> -            break;
> -
> -        if (ret != 8)
> -            break;
> -
> -        do {
> -            nevents = io_getevents(s->ctx, val, MAX_EVENTS, events, &ts);
> +            nevents = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS, events, &ts);
>          } while (nevents == -EINTR);
>  
>          for (i = 0; i < nevents; i++) {
> @@ -112,9 +100,9 @@ static void qemu_laio_completion_cb(void *opaque)
>      }
>  }
>  
> -static int qemu_laio_flush_cb(void *opaque)
> +static int qemu_laio_flush_cb(EventNotifier *e)
>  {
> -    struct qemu_laio_state *s = opaque;
> +    struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
>  
>      return (s->count > 0) ? 1 : 0;
>  }
> @@ -146,8 +134,9 @@ static void laio_cancel(BlockDriverAIOCB *blockacb)
>       * We might be able to do this slightly more optimal by removing the
>       * O_NONBLOCK flag.
>       */
> -    while (laiocb->ret == -EINPROGRESS)
> -        qemu_laio_completion_cb(laiocb->ctx);
> +    while (laiocb->ret == -EINPROGRESS) {
> +        qemu_laio_completion_cb(&laiocb->ctx->e);
> +    }
>  }
>  
>  static AIOPool laio_pool = {
> @@ -186,7 +175,7 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
>                          __func__, type);
>          goto out_free_aiocb;
>      }
> -    io_set_eventfd(&laiocb->iocb, s->efd);
> +    io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
>      s->count++;
>  
>      if (io_submit(s->ctx, 1, &iocbs) < 0)
> @@ -205,21 +194,21 @@ void *laio_init(void)
>      struct qemu_laio_state *s;
>  
>      s = g_malloc0(sizeof(*s));
> -    s->efd = eventfd(0, 0);
> -    if (s->efd == -1)
> +    if (event_notifier_init(&s->e, false) < 0) {
>          goto out_free_state;
> -    fcntl(s->efd, F_SETFL, O_NONBLOCK);
> +    }
>  
> -    if (io_setup(MAX_EVENTS, &s->ctx) != 0)
> +    if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
>          goto out_close_efd;
> +    }
>  
> -    qemu_aio_set_fd_handler(s->efd, qemu_laio_completion_cb, NULL,
> -        qemu_laio_flush_cb, s);
> +    qemu_aio_set_event_notifier(&s->e, qemu_laio_completion_cb,
> +                                qemu_laio_flush_cb);
>  
>      return s;
>  
>  out_close_efd:
> -    close(s->efd);
> +    event_notifier_cleanup(&s->e);
>  out_free_state:
>      g_free(s);
>      return NULL;
> -- 
> 1.7.10.4