* Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
2019-11-28 18:11 [PATCH v2] qga: fence guest-set-time if hwclock not available Cornelia Huck
@ 2019-11-28 18:38 ` Laszlo Ersek
2019-11-29 7:56 ` Cornelia Huck
2019-11-29 9:35 ` Daniel P. Berrangé
` (2 subsequent siblings)
3 siblings, 1 reply; 6+ messages in thread
From: Laszlo Ersek @ 2019-11-28 18:38 UTC (permalink / raw)
To: Cornelia Huck, Michael Roth; +Cc: Daniel P . Berrangé, qemu-devel
Hi Cornelia,
On 11/28/19 19:11, Cornelia Huck wrote:
> The Posix implementation of guest-set-time invokes hwclock to
> set/retrieve the time to/from the hardware clock. If hwclock
> is not available, the user is currently informed that "hwclock
> failed to set hardware clock to system time", which is quite
> misleading. This may happen e.g. on s390x, which has a different
> timekeeping concept anyway.
>
> Let's check for the availability of the hwclock command and
> return QERR_UNSUPPORTED for guest-set-time if it is not available.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
>
> v1 (RFC) -> v2:
> - use hwclock_path[]
> - use access() instead of stat()
>
> ---
> qga/commands-posix.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 1c1a165daed8..ffb6420fa9cd 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -156,6 +156,17 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> pid_t pid;
> Error *local_err = NULL;
> struct timeval tv;
> + const char hwclock_path[] = "/sbin/hwclock";
Did you drop the "static" storage-class specifier on purpose?
> + static int hwclock_available = -1;
> +
> + if (hwclock_available < 0) {
> + hwclock_available = (access(hwclock_path, X_OK) == 0);
> + }
> +
> + if (!hwclock_available) {
> + error_setg(errp, QERR_UNSUPPORTED);
> + return;
> + }
>
> /* If user has passed a time, validate and set it. */
> if (has_time) {
> @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
>
> /* Use '/sbin/hwclock -w' to set RTC from the system time,
> * or '/sbin/hwclock -s' to set the system time from RTC. */
> - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s",
> + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s",
I think it's somewhat obscure now that arg="hwclock" is supposed to
match the last pathname component in hwclock_path="/sbin/hwclock".
There are multiple ways to compute "arg" like that, of course. But I
think they all look uglier than the above. So I'm fine if we just keep this.
If you purposely dropped the "static", then:
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
If you just missed the "static" and now intend to add it back, then for v3:
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Thanks
Laszlo
> NULL, environ);
> _exit(EXIT_FAILURE);
> } else if (pid < 0) {
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
2019-11-28 18:38 ` Laszlo Ersek
@ 2019-11-29 7:56 ` Cornelia Huck
0 siblings, 0 replies; 6+ messages in thread
From: Cornelia Huck @ 2019-11-29 7:56 UTC (permalink / raw)
To: Laszlo Ersek; +Cc: Daniel P . Berrangé, Michael Roth, qemu-devel
On Thu, 28 Nov 2019 19:38:00 +0100
Laszlo Ersek <lersek@redhat.com> wrote:
> Hi Cornelia,
>
> On 11/28/19 19:11, Cornelia Huck wrote:
> > The Posix implementation of guest-set-time invokes hwclock to
> > set/retrieve the time to/from the hardware clock. If hwclock
> > is not available, the user is currently informed that "hwclock
> > failed to set hardware clock to system time", which is quite
> > misleading. This may happen e.g. on s390x, which has a different
> > timekeeping concept anyway.
> >
> > Let's check for the availability of the hwclock command and
> > return QERR_UNSUPPORTED for guest-set-time if it is not available.
> >
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
> >
> > v1 (RFC) -> v2:
> > - use hwclock_path[]
> > - use access() instead of stat()
> >
> > ---
> > qga/commands-posix.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> > index 1c1a165daed8..ffb6420fa9cd 100644
> > --- a/qga/commands-posix.c
> > +++ b/qga/commands-posix.c
> > @@ -156,6 +156,17 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> > pid_t pid;
> > Error *local_err = NULL;
> > struct timeval tv;
> > + const char hwclock_path[] = "/sbin/hwclock";
>
> Did you drop the "static" storage-class specifier on purpose?
No, I just need to do patches when I'm less tired :/
>
> > + static int hwclock_available = -1;
> > +
> > + if (hwclock_available < 0) {
> > + hwclock_available = (access(hwclock_path, X_OK) == 0);
> > + }
> > +
> > + if (!hwclock_available) {
> > + error_setg(errp, QERR_UNSUPPORTED);
> > + return;
> > + }
> >
> > /* If user has passed a time, validate and set it. */
> > if (has_time) {
> > @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> >
> > /* Use '/sbin/hwclock -w' to set RTC from the system time,
> > * or '/sbin/hwclock -s' to set the system time from RTC. */
> > - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s",
> > + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s",
>
> I think it's somewhat obscure now that arg="hwclock" is supposed to
> match the last pathname component in hwclock_path="/sbin/hwclock".
>
> There are multiple ways to compute "arg" like that, of course. But I
> think they all look uglier than the above. So I'm fine if we just keep this.
Yes, I was not able to come up with something elegant, either.
[Side note: does really everyone put hwclock under /sbin (i.e., nobody
doing something creative?)]
>
>
> If you purposely dropped the "static", then:
>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>
> If you just missed the "static" and now intend to add it back, then for v3:
>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>
> Thanks
> Laszlo
Thanks for looking! There'll be a v3.
>
>
>
> > NULL, environ);
> > _exit(EXIT_FAILURE);
> > } else if (pid < 0) {
> >
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
2019-11-28 18:11 [PATCH v2] qga: fence guest-set-time if hwclock not available Cornelia Huck
2019-11-28 18:38 ` Laszlo Ersek
@ 2019-11-29 9:35 ` Daniel P. Berrangé
2019-12-04 14:12 ` Cornelia Huck
2019-12-04 15:05 ` Michael Roth
3 siblings, 0 replies; 6+ messages in thread
From: Daniel P. Berrangé @ 2019-11-29 9:35 UTC (permalink / raw)
To: Cornelia Huck; +Cc: Laszlo Ersek, Michael Roth, qemu-devel
On Thu, Nov 28, 2019 at 07:11:00PM +0100, Cornelia Huck wrote:
> The Posix implementation of guest-set-time invokes hwclock to
> set/retrieve the time to/from the hardware clock. If hwclock
> is not available, the user is currently informed that "hwclock
> failed to set hardware clock to system time", which is quite
> misleading. This may happen e.g. on s390x, which has a different
> timekeeping concept anyway.
>
> Let's check for the availability of the hwclock command and
> return QERR_UNSUPPORTED for guest-set-time if it is not available.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
>
> v1 (RFC) -> v2:
> - use hwclock_path[]
> - use access() instead of stat()
>
> ---
> qga/commands-posix.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
2019-11-28 18:11 [PATCH v2] qga: fence guest-set-time if hwclock not available Cornelia Huck
2019-11-28 18:38 ` Laszlo Ersek
2019-11-29 9:35 ` Daniel P. Berrangé
@ 2019-12-04 14:12 ` Cornelia Huck
2019-12-04 15:05 ` Michael Roth
3 siblings, 0 replies; 6+ messages in thread
From: Cornelia Huck @ 2019-12-04 14:12 UTC (permalink / raw)
To: Michael Roth; +Cc: Laszlo Ersek, Daniel P . Berrangé, qemu-devel
On Thu, 28 Nov 2019 19:11:00 +0100
Cornelia Huck <cohuck@redhat.com> wrote:
> The Posix implementation of guest-set-time invokes hwclock to
> set/retrieve the time to/from the hardware clock. If hwclock
> is not available, the user is currently informed that "hwclock
> failed to set hardware clock to system time", which is quite
> misleading. This may happen e.g. on s390x, which has a different
> timekeeping concept anyway.
>
> Let's check for the availability of the hwclock command and
> return QERR_UNSUPPORTED for guest-set-time if it is not available.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Michael, any comments before I send a v3?
> ---
>
> v1 (RFC) -> v2:
> - use hwclock_path[]
> - use access() instead of stat()
>
> ---
> qga/commands-posix.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 1c1a165daed8..ffb6420fa9cd 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -156,6 +156,17 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> pid_t pid;
> Error *local_err = NULL;
> struct timeval tv;
> + const char hwclock_path[] = "/sbin/hwclock";
> + static int hwclock_available = -1;
> +
> + if (hwclock_available < 0) {
> + hwclock_available = (access(hwclock_path, X_OK) == 0);
> + }
> +
> + if (!hwclock_available) {
> + error_setg(errp, QERR_UNSUPPORTED);
> + return;
> + }
>
> /* If user has passed a time, validate and set it. */
> if (has_time) {
> @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
>
> /* Use '/sbin/hwclock -w' to set RTC from the system time,
> * or '/sbin/hwclock -s' to set the system time from RTC. */
> - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s",
> + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s",
> NULL, environ);
> _exit(EXIT_FAILURE);
> } else if (pid < 0) {
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
2019-11-28 18:11 [PATCH v2] qga: fence guest-set-time if hwclock not available Cornelia Huck
` (2 preceding siblings ...)
2019-12-04 14:12 ` Cornelia Huck
@ 2019-12-04 15:05 ` Michael Roth
3 siblings, 0 replies; 6+ messages in thread
From: Michael Roth @ 2019-12-04 15:05 UTC (permalink / raw)
To: Cornelia Huck
Cc: Laszlo Ersek, Cornelia Huck, Daniel P . Berrangé, qemu-devel
Quoting Cornelia Huck (2019-11-28 12:11:00)
> The Posix implementation of guest-set-time invokes hwclock to
> set/retrieve the time to/from the hardware clock. If hwclock
> is not available, the user is currently informed that "hwclock
> failed to set hardware clock to system time", which is quite
> misleading. This may happen e.g. on s390x, which has a different
> timekeeping concept anyway.
>
> Let's check for the availability of the hwclock command and
> return QERR_UNSUPPORTED for guest-set-time if it is not available.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> ---
>
> v1 (RFC) -> v2:
> - use hwclock_path[]
> - use access() instead of stat()
>
> ---
> qga/commands-posix.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 1c1a165daed8..ffb6420fa9cd 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -156,6 +156,17 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> pid_t pid;
> Error *local_err = NULL;
> struct timeval tv;
> + const char hwclock_path[] = "/sbin/hwclock";
> + static int hwclock_available = -1;
> +
> + if (hwclock_available < 0) {
> + hwclock_available = (access(hwclock_path, X_OK) == 0);
> + }
> +
> + if (!hwclock_available) {
> + error_setg(errp, QERR_UNSUPPORTED);
> + return;
> + }
>
> /* If user has passed a time, validate and set it. */
> if (has_time) {
> @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
>
> /* Use '/sbin/hwclock -w' to set RTC from the system time,
> * or '/sbin/hwclock -s' to set the system time from RTC. */
> - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s",
> + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s",
> NULL, environ);
> _exit(EXIT_FAILURE);
> } else if (pid < 0) {
> --
> 2.21.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread