From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34622) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZliYT-0000FX-G8 for qemu-devel@nongnu.org; Mon, 12 Oct 2015 15:14:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZliYQ-00026U-4z for qemu-devel@nongnu.org; Mon, 12 Oct 2015 15:14:41 -0400 Received: from relay.parallels.com ([195.214.232.42]:52488) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZliYP-00026N-NG for qemu-devel@nongnu.org; Mon, 12 Oct 2015 15:14:38 -0400 References: <1444215574-11895-1-git-send-email-den@openvz.org> <1444215574-11895-3-git-send-email-den@openvz.org> <20151012173812.10003.73590@loki> <561BFE70.6000605@weilnetz.de> From: "Denis V. Lunev" Message-ID: <561C0690.1050004@openvz.org> Date: Mon, 12 Oct 2015 22:14:24 +0300 MIME-Version: 1.0 In-Reply-To: <561BFE70.6000605@weilnetz.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/2] qga: set file descriptors in qmp_guest_file_open non-blocking on Win32 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Weil , Michael Roth Cc: Olga Krishtal , qemu-devel@nongnu.org On 10/12/2015 09:39 PM, Stefan Weil wrote: > Hi, > > please see my inline comments below. > > Am 12.10.2015 um 19:38 schrieb Michael Roth: >> Quoting Denis V. Lunev (2015-10-07 05:59:34) >>> From: Olga Krishtal >>> >>> Set fd non-blocking to avoid common use cases (like reading from a >>> named pipe) from hanging the agent. This was missed in the original >>> code. >>> >>> Restore compatibility with Posix implementation. >>> >>> The patch adds Win32 specific implementation of qemu_set_nonblock. >>> >>> On Windows OS there is a separate API for changing flags of file, pipes >>> and sockets. Portable way to change file descriptor flags requires >>> to detect file descriptor type and proper actions depending of that >>> type. The patch adds wrapper qemu_set_fd_nonblocking into Windows specific >>> code to handle this stuff properly. >>> >>> The only problem is that qemu_set_nonblock is void but this should not >>> be a big deal. >>> >>> Signed-off-by: Olga Krishtal >>> Signed-off-by: Denis V. Lunev >>> Reviewed-by: Yuri Pudgorodskiy >>> CC: Michael Roth >>> CC: Stefan Weil >>> --- >>> qga/commands-win32.c | 6 ++++++ >>> util/oslib-win32.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++----- >>> 2 files changed, 53 insertions(+), 5 deletions(-) >>> >>> diff --git a/qga/commands-win32.c b/qga/commands-win32.c >>> index 3374678..3274417 100644 >>> --- a/qga/commands-win32.c >>> +++ b/qga/commands-win32.c >>> @@ -34,6 +34,7 @@ >>> #include "qapi/qmp/qerror.h" >>> #include "qemu/queue.h" >>> #include "qemu/host-utils.h" >>> +#include "qemu/sockets.h" >>> >>> #ifndef SHTDN_REASON_FLAG_PLANNED >>> #define SHTDN_REASON_FLAG_PLANNED 0x80000000 >>> @@ -158,6 +159,11 @@ int64_t qmp_guest_file_open(const char *path, bool has_mode, >>> return -1; >>> } >>> >>> + /* set fd non-blocking to avoid common use cases (like reading from a >>> + * named pipe) from hanging the agent >>> + */ >>> + qemu_set_nonblock(fileno(fh)); >>> + >>> fd = guest_file_handle_add(fh, errp); >>> if (fd < 0) { >>> CloseHandle(&fh); >>> diff --git a/util/oslib-win32.c b/util/oslib-win32.c >>> index 08f5a9c..f19aed5 100644 >>> --- a/util/oslib-win32.c >>> +++ b/util/oslib-win32.c >>> @@ -121,17 +121,59 @@ struct tm *localtime_r(const time_t *timep, struct tm *result) >>> } >>> #endif /* CONFIG_LOCALTIME_R */ >>> >>> -void qemu_set_block(int fd) >>> +static void qemu_set_fd_nonblocking(int fd, bool nonblocking) >>> { >>> - unsigned long opt = 0; >>> - WSAEventSelect(fd, NULL, 0); >>> + HANDLE handle; >>> + DWORD file_type, pipe_state; >>> + >>> + handle = (HANDLE)_get_osfhandle(fd); >>> + if (handle == INVALID_HANDLE_VALUE) { >>> + return; >>> + } >>> + >>> + file_type = GetFileType(handle); >>> + if (file_type != FILE_TYPE_PIPE) { >>> + return; >>> + } >>> + >>> + /* If file_type == FILE_TYPE_PIPE, according to msdn >>> + * the specified file is socket or named pipe */ > ... or an anonymous pipe. ok >>> + if (GetNamedPipeHandleState(handle, &pipe_state, NULL, >>> + NULL, NULL, NULL, 0)) { >>> + /* The fd is named pipe fd */ > pipe_state could be declared here. not ok. pipe_state is initialized in GetNamedPipeHandleState above, which is in the main scope of the function >>> + if (!nonblocking == !(pipe_state & PIPE_NOWAIT)) { >>> + /* In this case we do not need perform any operation, because >>> + * nonblocking = true and PIPE_NOWAIT is already set or >>> + * nonblocking = false and PIPE_NOWAIT is not set */ >>> + return; >>> + } >>> + >>> + if (nonblocking) { >>> + pipe_state |= PIPE_NOWAIT; >>> + } else { >>> + pipe_state &= ~PIPE_NOWAIT; >>> + } >>> + >>> + SetNamedPipeHandleState(handle, &pipe_state, NULL, NULL); >>> + return; >>> + } >>> + >>> + /* The fd is socket fd */ >>> + unsigned long opt = (unsigned long)nonblocking; > The QEMU style still requires variable declarations at the beginning of > a code block. ok >>> + if (!nonblocking) { >>> + WSAEventSelect(fd, NULL, 0); >>> + } >>> ioctlsocket(fd, FIONBIO, &opt); >>> } >>> >>> +void qemu_set_block(int fd) >>> +{ >>> + qemu_set_fd_nonblocking(fd, false); >>> +} >>> + >>> void qemu_set_nonblock(int fd) >>> { >>> - unsigned long opt = 1; >>> - ioctlsocket(fd, FIONBIO, &opt); >>> + qemu_set_fd_nonblocking(fd, true); >>> qemu_fd_register(fd); >> This still potentially calls qemu_fd_register() on a non-socket FD as >> noted in prior review. I think the fix is trivial, but if you can >> change and re-test that would be ideal. > Yes. sure :) already discussed >> Since guest-file* already supports reading/writing to w32 pipes I can >> pick this up during soft-freeze if it comes to that. >> >> Since we're still taking the approach of generalizing >> qemu_set_nonblock() for win32 I'd really prefer to get Stefan's >> Ack/Reviewed-by before applying. >> >>> } > I'm sorry that I cannot run any tests, but as far as I can see, > the code will be fine if all the notes are taken into account. > > Regards > Stefan >