From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:57251) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfY53-0000Vt-3e for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:05:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfY4x-000470-9k for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:04:56 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:58243) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfY4x-00046M-1T for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:04:51 -0400 Received: from /spool/local by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 15 Jun 2012 09:04:46 -0600 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id BDBBBC90065 for ; Fri, 15 Jun 2012 11:04:23 -0400 (EDT) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q5FF4O5g182198 for ; Fri, 15 Jun 2012 11:04:24 -0400 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q5FF4OJc027412 for ; Fri, 15 Jun 2012 12:04:24 -0300 Message-ID: <4FDB4EF0.2020500@linux.vnet.ibm.com> Date: Fri, 15 Jun 2012 11:04:16 -0400 From: Corey Bryant MIME-Version: 1.0 References: <1339689305-27031-1-git-send-email-coreyb@linux.vnet.ibm.com> <1339689305-27031-3-git-send-email-coreyb@linux.vnet.ibm.com> <20120615113248.7eea2ead@doriath.home> In-Reply-To: <20120615113248.7eea2ead@doriath.home> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 2/5] qapi: Add pass-fd QMP command List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: kwolf@redhat.com, aliguori@us.ibm.com, stefanha@linux.vnet.ibm.com, libvir-list@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, eblake@redhat.com On 06/15/2012 10:32 AM, Luiz Capitulino wrote: > On Thu, 14 Jun 2012 11:55:02 -0400 > Corey Bryant wrote: > >> This patch adds the pass-fd QMP command using the QAPI framework. >> Like the getfd command, it is used to pass a file descriptor via >> SCM_RIGHTS. However, the pass-fd command also returns the received >> file descriptor, which is a difference in behavior from the getfd >> command, which returns nothing. >> >> The closefd command can be used to close a file descriptor that was >> passed with the pass-fd command. >> >> Note that when using getfd or pass-fd, there are some commands >> (e.g. migrate with fd:name) that implicitly close the named fd. >> When this is not the case, closefd must be used to avoid fd leaks. >> >> Signed-off-by: Corey Bryant >> --- >> v2: >> -Introduce new QMP command to pass/return fd (lcapitulino@redhat.com) >> -Use passfd as command name (berrange@redhat.com) >> >> v3: >> -Use pass-fd as command name (lcapitulino@redhat.com) >> -Fail pass-fd if fdname already exists (lcapitulino@redhat.com) >> -Add notes to QMP command describing behavior in more detail >> (lcapitulino@redhat.com, eblake@redhat.com) >> -Add note about fd leakage (eblake@redhat.com) >> >> monitor.c | 33 +++++++++++++++++++++++++++++++++ >> qapi-schema.json | 19 +++++++++++++++++++ >> qmp-commands.hx | 34 ++++++++++++++++++++++++++++++++++ >> 3 files changed, 86 insertions(+) >> >> diff --git a/monitor.c b/monitor.c >> index 1a7f7e7..6d99368 100644 >> --- a/monitor.c >> +++ b/monitor.c >> @@ -2182,6 +2182,39 @@ static void do_inject_mce(Monitor *mon, const QDict *qdict) >> } >> #endif >> >> +int64_t qmp_pass_fd(const char *fdname, Error **errp) >> +{ >> + mon_fd_t *monfd; >> + int fd; >> + >> + fd = qemu_chr_fe_get_msgfd(cur_mon->chr); >> + if (fd == -1) { >> + error_set(errp, QERR_FD_NOT_SUPPLIED); >> + return -1; >> + } >> + >> + if (qemu_isdigit(fdname[0])) { >> + error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdname", >> + "a name not starting with a digit"); >> + return -1; >> + } >> + >> + QLIST_FOREACH(monfd, &cur_mon->fds, next) { >> + if (strcmp(monfd->name, fdname) == 0) { >> + error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdname", >> + "a name that does not already exist"); >> + return -1; >> + } >> + } > > Returning the same error class for two different errors is not a good idea. > I think you have two options here. You could return QERR_INVALID_PARAMETER > for the "already exists" case or introduce QERR_FD_EXISTS. The later is > certainly nicer, but we were trying to avoid having too specific errors... > I'm not clear on what the problem is with returning the same error class for two different errors. Could you explain? I don't have a problem changing it if it's an issue. >> + >> + monfd = g_malloc0(sizeof(mon_fd_t)); >> + monfd->name = g_strdup(fdname); >> + monfd->fd = fd; > > Maybe you could try to move this to a separate function to share code with > qmp_getfd()? > Sure, no problem. I can do that. >> + >> + QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next); >> + return fd; >> +} >> + >> void qmp_getfd(const char *fdname, Error **errp) >> { >> mon_fd_t *monfd; >> diff --git a/qapi-schema.json b/qapi-schema.json >> index 26a6b84..ed99f23 100644 >> --- a/qapi-schema.json >> +++ b/qapi-schema.json >> @@ -1864,6 +1864,25 @@ >> { 'command': 'netdev_del', 'data': {'id': 'str'} } >> >> ## >> +# @pass-fd: >> +# >> +# Pass a file descriptor via SCM rights and assign it a name >> +# >> +# @fdname: file descriptor name >> +# >> +# Returns: The QEMU file descriptor that was received >> +# If file descriptor was not received, FdNotSupplied >> +# If @fdname is not valid, InvalidParameterType >> +# >> +# Since: 1.2.0 >> +# >> +# Notes: If @fdname already exists, the command will fail. >> +# The 'closefd' command can be used to explicitly close the >> +# file descriptor when it is no longer needed. >> +## >> +{ 'command': 'pass-fd', 'data': {'fdname': 'str'}, 'returns': 'int' } >> + >> +## >> # @getfd: >> # >> # Receive a file descriptor via SCM rights and assign it a name >> diff --git a/qmp-commands.hx b/qmp-commands.hx >> index e3cf3c5..c039947 100644 >> --- a/qmp-commands.hx >> +++ b/qmp-commands.hx >> @@ -869,6 +869,40 @@ Example: >> EQMP >> >> { >> + .name = "pass-fd", >> + .args_type = "fdname:s", >> + .params = "pass-fd name", >> + .help = "pass a file descriptor via SCM rights and assign it a name", >> + .mhandler.cmd_new = qmp_marshal_input_pass_fd, >> + }, >> + >> +SQMP >> +pass-fd >> +------- >> + >> +Pass a file descriptor via SCM rights and assign it a name. >> + >> +Arguments: >> + >> +- "fdname": file descriptor name (json-string) >> + >> +Return a json-int with the QEMU file descriptor that was received. >> + >> +Example: >> + >> +-> { "execute": "pass-fd", "arguments": { "fdname": "fd1" } } >> +<- { "return": 42 } >> + >> +Notes: >> + >> +(1) If the name specified by the "fdname" argument already exists, >> + the command will fail. >> +(2) The 'closefd' command can be used to explicitly close the file >> + descriptor when it is no longer needed. >> + >> +EQMP >> + >> + { >> .name = "getfd", >> .args_type = "fdname:s", >> .params = "getfd name", > > -- Regards, Corey