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Re: [PATCH v3] qga: fence guest-set-time if hwclock not available
From: |
Markus Armbruster |
Subject: |
Re: [PATCH v3] qga: fence guest-set-time if hwclock not available |
Date: |
Fri, 06 Dec 2019 08:17:27 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Cornelia Huck <address@hidden> writes:
> On Thu, 5 Dec 2019 14:05:19 +0100
> Philippe Mathieu-Daudé <address@hidden> wrote:
>
>> Hi Cornelia,
>>
>> On 12/5/19 12:53 PM, 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.
>> >
>> > Reviewed-by: Laszlo Ersek <address@hidden>
>> > Reviewed-by: Daniel P. Berrangé <address@hidden>
>> > Reviewed-by: Michael Roth <address@hidden>
>> > Signed-off-by: Cornelia Huck <address@hidden>
>> > ---
>> >
>> > v2->v3:
>> > - added 'static' keyword to hwclock_path
>> >
>> > Not sure what tree this is going through; if there's no better place,
>> > I can also take this through the s390 tree.
>>
>> s390 or trivial trees seems appropriate.
>>
>> >
>> > ---
>> > 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..0be301a4ea77 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;
>> > + static 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);
>>
>> In include/qapi/qmp/qerror.h we have:
>>
>> /*
>> * These macros will go away, please don't use in new code, and do not
>> * add new ones!
>> */
>
> Sigh, it is really hard to keep track here :( I just copied from other
> callers in this file...
I'm not faulting you for that.
I think this new use is acceptable. For details, see my other reply in
this thread.
[...]
Re: [PATCH v3] qga: fence guest-set-time if hwclock not available, Cornelia Huck, 2019/12/10