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Re: [PATCH v3 2/2] error handling: Use RETRY_ON_EINTR() macro where appl


From: Nikita Ivanov
Subject: Re: [PATCH v3 2/2] error handling: Use RETRY_ON_EINTR() macro where applicable
Date: Sun, 23 Oct 2022 12:05:50 +0300

Hi!
Thanks for clarification! Corrected it in v4.

On Wed, Oct 19, 2022 at 6:24 PM Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
On Tuesday, October 18, 2022 10:43:41 AM CEST Nikita Ivanov wrote:
> There is a defined RETRY_ON_EINTR() macro in qemu/osdep.h
> which handles the same while loop.
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/415
>
> Signed-off-by: Nikita Ivanov <nivanov@cloudlinux.com>
> ---
>  block/file-posix.c        | 37 ++++++++++++++++---------------------
>  chardev/char-pty.c        |  4 +---
>  hw/9pfs/9p-local.c        |  8 ++------
>  net/l2tpv3.c              | 17 +++++------------
>  net/socket.c              | 16 +++++++---------
>  net/tap.c                 |  8 ++------
>  qga/commands-posix.c      |  4 +---
>  semihosting/syscalls.c    |  4 +---
>  tests/qtest/libqtest.c    | 12 +++++-------
>  tests/vhost-user-bridge.c |  4 +---
>  util/main-loop.c          |  4 +---
>  util/osdep.c              |  4 +---
>  util/vfio-helpers.c       | 12 ++++++------
>  13 files changed, 49 insertions(+), 85 deletions(-)
>
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 23acffb9a4..8f7a22e3e4 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -1229,9 +1229,7 @@ static int hdev_get_max_segments(int fd, struct stat *st)
>          ret = -errno;
>          goto out;
>      }
> -    do {
> -        ret = read(sysfd, buf, sizeof(buf) - 1);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(read(sysfd, buf, sizeof(buf) - 1));
>      if (ret < 0) {
>          ret = -errno;
>          goto out;
> @@ -1379,9 +1377,9 @@ static int handle_aiocb_ioctl(void *opaque)
>      RawPosixAIOData *aiocb = opaque;
>      int ret;

> -    do {
> -        ret = ioctl(aiocb->aio_fildes, aiocb->ioctl.cmd, aiocb->ioctl.buf);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(
> +        ioctl(aiocb->aio_fildes, aiocb->ioctl.cmd, aiocb->ioctl.buf)
> +    );
>      if (ret == -1) {
>          return -errno;
>      }
> @@ -1463,18 +1461,17 @@ static ssize_t handle_aiocb_rw_vector(RawPosixAIOData *aiocb)
>  {
>      ssize_t len;

> -    do {
> -        if (aiocb->aio_type & QEMU_AIO_WRITE)
> -            len = qemu_pwritev(aiocb->aio_fildes,
> -                               aiocb->io.iov,
> -                               aiocb->io.niov,
> -                               aiocb->aio_offset);
> -         else
> -            len = qemu_preadv(aiocb->aio_fildes,
> -                              aiocb->io.iov,
> -                              aiocb->io.niov,
> -                              aiocb->aio_offset);
> -    } while (len == -1 && errno == EINTR);
> +    len = RETRY_ON_EINTR(
> +        (aiocb->aio_type & QEMU_AIO_WRITE) ?
> +            qemu_pwritev(aiocb->aio_fildes,
> +                           aiocb->io.iov,
> +                           aiocb->io.niov,
> +                           aiocb->aio_offset) :
> +            qemu_preadv(aiocb->aio_fildes,
> +                          aiocb->io.iov,
> +                          aiocb->io.niov,
> +                          aiocb->aio_offset)
> +    );

>      if (len == -1) {
>          return -errno;
> @@ -1899,9 +1896,7 @@ static int allocate_first_block(int fd, size_t max_size)
>      buf = qemu_memalign(max_align, write_size);
>      memset(buf, 0, write_size);

> -    do {
> -        n = pwrite(fd, buf, write_size, 0);
> -    } while (n == -1 && errno == EINTR);
> +    n = RETRY_ON_EINTR(pwrite(fd, buf, write_size, 0));

>      ret = (n == -1) ? -errno : 0;

> diff --git a/chardev/char-pty.c b/chardev/char-pty.c
> index 53f25c6bbd..92fd33c854 100644
> --- a/chardev/char-pty.c
> +++ b/chardev/char-pty.c
> @@ -93,9 +93,7 @@ static void pty_chr_update_read_handler(Chardev *chr)
>      pfd.fd = fioc->fd;
>      pfd.events = G_IO_OUT;
>      pfd.revents = 0;
> -    do {
> -        rc = g_poll(&pfd, 1, 0);
> -    } while (rc == -1 && errno == EINTR);
> +    rc = RETRY_ON_EINTR(g_poll(&pfd, 1, 0));
>      assert(rc >= 0);

>      if (pfd.revents & G_IO_HUP) {
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index d42ce6d8b8..bb3187244f 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -470,9 +470,7 @@ static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
>          if (fd == -1) {
>              return -1;
>          }
> -        do {
> -            tsize = read(fd, (void *)buf, bufsz);
> -        } while (tsize == -1 && errno == EINTR);
> +        tsize = RETRY_ON_EINTR(read(fd, (void *)buf, bufsz));
>          close_preserve_errno(fd);
>      } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
>                 (fs_ctx->export_flags & V9FS_SM_NONE)) {
> @@ -908,9 +906,7 @@ static int local_symlink(FsContext *fs_ctx, const char *oldpath,
>          }
>          /* Write the oldpath (target) to the file. */
>          oldpath_size = strlen(oldpath);
> -        do {
> -            write_size = write(fd, (void *)oldpath, oldpath_size);
> -        } while (write_size == -1 && errno == EINTR);
> +        write_size = RETRY_ON_EINTR(write(fd, (void *)oldpath, oldpath_size));
>          close_preserve_errno(fd);

>          if (write_size != oldpath_size) {
> diff --git a/net/l2tpv3.c b/net/l2tpv3.c
> index af373e5c30..e0726f5f89 100644
> --- a/net/l2tpv3.c
> +++ b/net/l2tpv3.c
> @@ -240,9 +240,7 @@ static ssize_t net_l2tpv3_receive_dgram_iov(NetClientState *nc,
>      message.msg_control = NULL;
>      message.msg_controllen = 0;
>      message.msg_flags = 0;
> -    do {
> -        ret = sendmsg(s->fd, &message, 0);
> -    } while ((ret == -1) && (errno == EINTR));
> +    ret = RETRY_ON_EINTR(sendmsg(s->fd, &message, 0));
>      if (ret > 0) {
>          ret -= s->offset;
>      } else if (ret == 0) {
> @@ -285,9 +283,7 @@ static ssize_t net_l2tpv3_receive_dgram(NetClientState *nc,
>      message.msg_control = NULL;
>      message.msg_controllen = 0;
>      message.msg_flags = 0;
> -    do {
> -        ret = sendmsg(s->fd, &message, 0);
> -    } while ((ret == -1) && (errno == EINTR));
> +    ret = RETRY_ON_EINTR(sendmsg(s->fd, &message, 0));
>      if (ret > 0) {
>          ret -= s->offset;
>      } else if (ret == 0) {
> @@ -434,12 +430,9 @@ static void net_l2tpv3_send(void *opaque)

>      msgvec = s->msgvec + s->queue_head;
>      if (target_count > 0) {
> -        do {
> -            count = recvmmsg(
> -                s->fd,
> -                msgvec,
> -                target_count, MSG_DONTWAIT, NULL);
> -        } while ((count == -1) && (errno == EINTR));
> +        count = RETRY_ON_EINTR(
> +                recvmmsg(s->fd, msgvec, target_count, MSG_DONTWAIT, NULL)
> +        );
>          if (count < 0) {
>              /* Recv error - we still need to flush packets here,
>               * (re)set queue head to current position
> diff --git a/net/socket.c b/net/socket.c
> index bfd8596250..00f8a88531 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -117,15 +117,13 @@ static ssize_t net_socket_receive_dgram(NetClientState *nc, const uint8_t *buf,
>      NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);
>      ssize_t ret;

> -    do {
> -        if (s->dgram_dst.sin_family != AF_UNIX) {
> -            ret = sendto(s->fd, buf, size, 0,
> -                         (struct sockaddr *)&s->dgram_dst,
> -                         sizeof(s->dgram_dst));
> -        } else {
> -            ret = send(s->fd, buf, size, 0);
> -        }
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(
> +        s->dgram_dst.sin_family != AF_UNIX ?
> +            sendto(s->fd, buf, size, 0,
> +                     (struct sockaddr *)&s->dgram_dst,
> +                     sizeof(s->dgram_dst)) :
> +            send(s->fd, buf, size, 0)
> +    );

>      if (ret == -1 && errno == EAGAIN) {
>          net_socket_write_poll(s, true);
> diff --git a/net/tap.c b/net/tap.c
> index e090d14203..4c90f70b7e 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -102,9 +102,7 @@ static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt
>  {
>      ssize_t len;

> -    do {
> -        len = writev(s->fd, iov, iovcnt);
> -    } while (len == -1 && errno == EINTR);
> +    len = RETRY_ON_EINTR(writev(s->fd, iov, iovcnt));

>      if (len == -1 && errno == EAGAIN) {
>          tap_write_poll(s, true);
> @@ -577,9 +575,7 @@ static int net_bridge_run_helper(const char *helper, const char *bridge,

>          close(sv[1]);

> -        do {
> -            fd = recv_fd(sv[0]);
> -        } while (fd == -1 && errno == EINTR);
> +        fd = RETRY_ON_EINTR(recv_fd(sv[0]));
>          saved_errno = errno;

>          close(sv[0]);
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index eea819cff0..95753f7c96 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -68,9 +68,7 @@ static void ga_wait_child(pid_t pid, int *status, Error **errp)

>      *status = 0;

> -    do {
> -        rpid = waitpid(pid, status, 0);
> -    } while (rpid == -1 && errno == EINTR);
> +    rpid = RETRY_ON_EINTR(waitpid(pid, status, 0));

>      if (rpid == -1) {
>          error_setg_errno(errp, errno, "failed to wait for child (pid: %d)",
> diff --git a/semihosting/syscalls.c b/semihosting/syscalls.c
> index 508a0ad88c..5893c760c5 100644
> --- a/semihosting/syscalls.c
> +++ b/semihosting/syscalls.c
> @@ -317,9 +317,7 @@ static void host_read(CPUState *cs, gdb_syscall_complete_cb complete,
>          complete(cs, -1, EFAULT);
>          return;
>      }
> -    do {
> -        ret = read(gf->hostfd, ptr, len);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(read(gf->hostfd, ptr, len));
>      if (ret == -1) {
>          complete(cs, -1, errno);
>          unlock_user(ptr, buf, 0);
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index 90648eb8d1..86f1091e78 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -101,10 +101,10 @@ static int socket_accept(int sock)
>          return -1;
>      }

> -    do {
> -        addrlen = sizeof(addr);
> -        ret = accept(sock, (struct sockaddr *)&addr, &addrlen);
> -    } while (ret == -1 && errno == EINTR);
> +    addrlen = sizeof(addr);

That assignment was intentionally inside the loop, because the 3rd argument of
accept() is a result parameter, so the value of `addrlen` gets modified and
hence `addrlen` has to be restored in each loop cycle.

> +    ret = RETRY_ON_EINTR(
> +        accept(sock, (struct sockaddr *)&addr, &addrlen)
> +    );
>      if (ret == -1) {
>          fprintf(stderr, "%s failed: %s\n", __func__, strerror(errno));
>      }
> @@ -574,9 +574,7 @@ int qtest_socket_server(const char *socket_path)
>      addr.sun_family = AF_UNIX;
>      snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", socket_path);

> -    do {
> -        ret = bind(sock, (struct sockaddr *)&addr, sizeof(addr));
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(bind(sock, (struct sockaddr *)&addr, sizeof(addr)));
>      g_assert_cmpint(ret, !=, -1);
>      ret = listen(sock, 1);
>      g_assert_cmpint(ret, !=, -1);
> diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
> index fecdf915e7..a5c711b1de 100644
> --- a/tests/vhost-user-bridge.c
> +++ b/tests/vhost-user-bridge.c
> @@ -331,9 +331,7 @@ vubr_backend_recv_cb(int sock, void *ctx)
>              .msg_iovlen = num,
>              .msg_flags = MSG_DONTWAIT,
>          };
> -        do {
> -            ret = recvmsg(vubr->backend_udp_sock, &msg, 0);
> -        } while (ret == -1 && (errno == EINTR));
> +        ret = RETRY_ON_EINTR(recvmsg(vubr->backend_udp_sock, &msg, 0));

>          if (i == 0) {
>              iov_restore_front(elem->in_sg, sg, hdrlen);
> diff --git a/util/main-loop.c b/util/main-loop.c
> index f00a25451b..63bd5d123d 100644
> --- a/util/main-loop.c
> +++ b/util/main-loop.c
> @@ -64,9 +64,7 @@ static void sigfd_handler(void *opaque)
>      ssize_t len;

>      while (1) {
> -        do {
> -            len = read(fd, &info, sizeof(info));
> -        } while (len == -1 && errno == EINTR);
> +        len = RETRY_ON_EINTR(read(fd, &info, sizeof(info)));

>          if (len == -1 && errno == EAGAIN) {
>              break;
> diff --git a/util/osdep.c b/util/osdep.c
> index 746d5f7d71..aa358bd65e 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -244,9 +244,7 @@ static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
>          .l_type   = fl_type,
>      };
>      qemu_probe_lock_ops();
> -    do {
> -        ret = fcntl(fd, fcntl_op_setlk, &fl);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(fcntl(fd, fcntl_op_setlk, &fl));
>      return ret == -1 ? -errno : 0;
>  }

> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index 5ba01177bf..1a9b338cf9 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -240,9 +240,9 @@ static int qemu_vfio_pci_read_config(QEMUVFIOState *s, void *buf,
>                                      s->config_region_info.offset,
>                                      s->config_region_info.size);
>      assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
> -    do {
> -        ret = pread(s->device, buf, size, s->config_region_info.offset + ofs);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(
> +        pread(s->device, buf, size, s->config_region_info.offset + ofs)
> +    );
>      return ret == size ? 0 : -errno;
>  }

> @@ -254,9 +254,9 @@ static int qemu_vfio_pci_write_config(QEMUVFIOState *s, void *buf, int size, int
>                                       s->config_region_info.offset,
>                                       s->config_region_info.size);
>      assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
> -    do {
> -        ret = pwrite(s->device, buf, size, s->config_region_info.offset + ofs);
> -    } while (ret == -1 && errno == EINTR);
> +    ret = RETRY_ON_EINTR(
> +        pwrite(s->device, buf, size, s->config_region_info.offset + ofs)
> +    );
>      return ret == size ? 0 : -errno;
>  }

>





--
Best Regards,
Nikita Ivanov | C developer
Telephone: +79140870696
Telephone: +79015053149

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