From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51697) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zli0o-0002NW-D4 for qemu-devel@nongnu.org; Mon, 12 Oct 2015 14:39:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zli0j-000843-8w for qemu-devel@nongnu.org; Mon, 12 Oct 2015 14:39:54 -0400 Received: from v220110690675601.yourvserver.net ([37.221.199.173]:44663) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zli0i-000830-Ul for qemu-devel@nongnu.org; Mon, 12 Oct 2015 14:39:49 -0400 Message-ID: <561BFE70.6000605@weilnetz.de> Date: Mon, 12 Oct 2015 20:39:44 +0200 From: Stefan Weil MIME-Version: 1.0 References: <1444215574-11895-1-git-send-email-den@openvz.org> <1444215574-11895-3-git-send-email-den@openvz.org> <20151012173812.10003.73590@loki> In-Reply-To: <20151012173812.10003.73590@loki> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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: Michael Roth , "Denis V. Lunev" Cc: Olga Krishtal , qemu-devel@nongnu.org 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, pipe= s >> 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 spec= ific >> 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, boo= l has_mode, >> return -1; >> } >> >> + /* set fd non-blocking to avoid common use cases (like reading fr= om a >> + * named pipe) from hanging the agent >> + */ >> + qemu_set_nonblock(fileno(fh)); >> + >> fd =3D 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, stru= ct 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 =3D 0; >> - WSAEventSelect(fd, NULL, 0); >> + HANDLE handle; >> + DWORD file_type, pipe_state; >> + >> + handle =3D (HANDLE)_get_osfhandle(fd); >> + if (handle =3D=3D INVALID_HANDLE_VALUE) { >> + return; >> + } >> + >> + file_type =3D GetFileType(handle); >> + if (file_type !=3D FILE_TYPE_PIPE) { >> + return; >> + } >> + >> + /* If file_type =3D=3D FILE_TYPE_PIPE, according to msdn >> + * the specified file is socket or named pipe */ ... or an anonymous pipe. >> + if (GetNamedPipeHandleState(handle, &pipe_state, NULL, >> + NULL, NULL, NULL, 0)) { >> + /* The fd is named pipe fd */ pipe_state could be declared here. >> + if (!nonblocking =3D=3D !(pipe_state & PIPE_NOWAIT)) { >> + /* In this case we do not need perform any operation, bec= ause >> + * nonblocking =3D true and PIPE_NOWAIT is already set or >> + * nonblocking =3D false and PIPE_NOWAIT is not set */ >> + return; >> + } >> + >> + if (nonblocking) { >> + pipe_state |=3D PIPE_NOWAIT; >> + } else { >> + pipe_state &=3D ~PIPE_NOWAIT; >> + } >> + >> + SetNamedPipeHandleState(handle, &pipe_state, NULL, NULL); >> + return; >> + } >> + >> + /* The fd is socket fd */ >> + unsigned long opt =3D (unsigned long)nonblocking; The QEMU style still requires variable declarations at the beginning of a code block. >> + 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 =3D 1; >> - ioctlsocket(fd, FIONBIO, &opt); >> + qemu_set_fd_nonblocking(fd, true); >> qemu_fd_register(fd); >=20 > 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. >=20 > Since guest-file* already supports reading/writing to w32 pipes I can > pick this up during soft-freeze if it comes to that. >=20 > 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. >=20 >> } 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