From: Ian Jackson <ian.jackson@citrix.com>
To: Anthony PERARD <anthony.perard@citrix.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Wei Liu <wei.liu2@citrix.com>
Subject: Re: [Xen-devel] [PATCH 4/9] libxl_internal: Create new lock for devices hotplug via QMP
Date: Wed, 5 Jun 2019 15:32:20 +0100 [thread overview]
Message-ID: <23799.53876.440475.866985@mariner.uk.xensource.com> (raw)
In-Reply-To: <20190605141015.GJ2126@perard.uk.xensource.com>
Anthony PERARD writes ("Re: [PATCH 4/9] libxl_internal: Create new lock for devices hotplug via QMP"):
> So, instead of that interface, how about a different one that uses the
> same C type for both kind of lock?
>
> libxl__lock *libxl__lock_domain_userdata(libxl__gc *, libxl_domid);
> libxl__lock *libxl__lock_domain_qmp(libxl__gc *, libxl_domid);
> void libxl__unlock(libxl__lock *);
I think that would be fine.
> Or maybe avoid having two functions for locking and use a #define/enum
> instead:
> libxl__lock_domain(gc, domid, LOCK_USERDATA);
> libxl__lock_domain(gc, domid, LOCK_QMP);
Or this.
But I think maybe this conversation will be superseded by the need to
redo the implementation which will result in a totally different API
for the slow lock, and probably a different state struct.
> What do you think? Would the first proposal be enough to avoid having to
> write `userdata' or `qmp' twice on unlock?
I don't *mind* the writing `userdata' or `qmp' twice. I just
discounting it as a *benefit*. I mind the duplicated implementation
code.
> > Maybe it would be better to try once with LOCK_NB, and to fork if this
> > is not successful. But it would be simpler to always fork...
>
> After our talk IRL, I'll go the fork route.
> Also, I'm thinking to always fork when libxl is built with "debug=y",
> and allow the optimisation of trying first with LOCK_NB when built with
> "debug=n", so the forked code will actually be tested regulary.
Good plan.
Ian.
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next prev parent reply other threads:[~2019-06-05 14:33 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 16:45 [PATCH 0/9] libxl: New slow lock + fix libxl_cdrom_insert with QEMU depriv Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-04-09 16:45 ` [PATCH 1/9] libxl_internal: Remove lost comment Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-04-10 9:18 ` Wei Liu
2019-04-10 9:18 ` [Xen-devel] " Wei Liu
2019-06-04 16:42 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 2/9] libxl: Pointer on usage of libxl__domain_userdata_lock Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 16:46 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 3/9] libxl_internal: Split out userdata lock function Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 16:55 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 4/9] libxl_internal: Create new lock for devices hotplug via QMP Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:11 ` Ian Jackson
2019-06-05 14:10 ` Anthony PERARD
2019-06-05 14:32 ` Ian Jackson [this message]
2019-04-09 16:45 ` [PATCH 5/9] libxl_disk: Reorganise libxl_cdrom_insert Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:16 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 6/9] libxl_disk: Cut libxl_cdrom_insert into steps Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:29 ` Ian Jackson
2019-06-07 17:22 ` Anthony PERARD
2019-04-09 16:45 ` [PATCH 7/9] libxl: Move qmp_parameters_* prototypes to libxl_internal.h Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:32 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 8/9] libxl_disk: Use ev_qmp in libxl_cdrom_insert Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:45 ` Ian Jackson
2019-04-09 16:45 ` [PATCH 9/9] libxl_disk: Implement missing timeout for libxl_cdrom_insert Anthony PERARD
2019-04-09 16:45 ` [Xen-devel] " Anthony PERARD
2019-06-04 17:47 ` Ian Jackson
2019-06-05 14:22 ` Anthony PERARD
2019-06-05 14:33 ` Ian Jackson
2019-06-04 10:54 ` [Xen-devel] Ping: [PATCH 0/9] libxl: New slow lock + fix libxl_cdrom_insert with QEMU depriv Anthony PERARD
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