Re: [PATCH v2] nwfilter: fix deadlock caused updating network device and nwfilter

[Pavel Hrdina <phrdina@xxxxxxxxxx>]

On 11/12/2014 05:17 PM, John Ferlan wrote:
> On 11/12/2014 04:51 AM, Pavel Hrdina wrote:
> > Commit 6e5c79a1 tried to fix deadlock between nwfilter{Define,Undefine}
> > and starting of guest, but this same deadlock is also for
>
> s/is also/exists/
>
> > updating/attaching network device to domain.
> >
> > The deadlock was introduced by removing global QEMU driver lock because
> > nwfilter was counting on this lock and ensure that all driver locks are
> > locked inside of nwfilter{Define,Undefine}.
> >
> > This patch extends usage of virNWFilterReadLockFilterUpdates to prevent
> > the deadlock for all possible paths in QEMU driver. LXC and UML drivers
> > still have global lock.
> >
> > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1143780
> >
> > Signed-off-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
> > ---
> >   src/qemu/qemu_driver.c    | 12 ++++++++++++
> >   src/qemu/qemu_migration.c |  3 +++
> >   src/qemu/qemu_process.c   |  4 ++++
> >   3 files changed, 19 insertions(+)
>
> I thought I had built these yesterday when reviewing, but apparently not
> as doing a build just now failed because the symbols are not defined in
> qemu_migration.c and qemu_process.c (I have gcc version 4.8.3 20140911
> (Red Hat 4.8.3-7) (GCC) on my f20 box)
>
> I squashed the following and it builds...
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 533bb35..9106800 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -50,6 +50,7 @@
>   #include "viruuid.h"
>   #include "virtime.h"
>   #include "locking/domain_lock.h"
> +#include "nwfilter_conf.h"
>   #include "rpc/virnetsocket.h"
>   #include "virstoragefile.h"
>   #include "viruri.h"
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 0078a70..1c1476c 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -57,6 +57,7 @@
>   #include "domain_nwfilter.h"
>   #include "locking/domain_lock.h"
>   #include "network/bridge_driver.h"
> +#include "nwfilter_conf.h"
>   #include "viruuid.h"
>   #include "virprocess.h"
>   #include "virtime.h"
>
> ACK with the squashed in #includes

Thanks, I've already found that build issue and fixed it.

> John
> > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> > index 56e8430..716e9a4 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -5902,6 +5902,8 @@ qemuDomainRestoreFlags(virConnectPtr conn,
> >                     VIR_DOMAIN_SAVE_PAUSED, -1);
> >
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       fd = qemuDomainSaveImageOpen(driver, path, &def, &header, &xml,
> >                                    (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
> >                                    &wrapperFd, false, false);
> > @@ -5979,6 +5981,7 @@ qemuDomainRestoreFlags(virConnectPtr conn,
> >       virFileWrapperFdFree(wrapperFd);
> >       if (vm)
> >           virObjectUnlock(vm);
> > +    virNWFilterUnlockFilterUpdates();
> >       return ret;
> >   }
> >
> > @@ -7500,6 +7503,8 @@ static int qemuDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
> >       virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
> >                     VIR_DOMAIN_AFFECT_CONFIG, -1);
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       cfg = virQEMUDriverGetConfig(driver);
> >
> >       affect = flags & (VIR_DOMAIN_AFFECT_LIVE | VIR_DOMAIN_AFFECT_CONFIG);
> > @@ -7616,6 +7621,7 @@ static int qemuDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
> >           virObjectUnlock(vm);
> >       virObjectUnref(caps);
> >       virObjectUnref(cfg);
> > +    virNWFilterUnlockFilterUpdates();
> >       return ret;
> >   }
> >
> > @@ -7646,6 +7652,8 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
> >                     VIR_DOMAIN_AFFECT_CONFIG |
> >                     VIR_DOMAIN_DEVICE_MODIFY_FORCE, -1);
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       cfg = virQEMUDriverGetConfig(driver);
> >
> >       affect = flags & (VIR_DOMAIN_AFFECT_LIVE | VIR_DOMAIN_AFFECT_CONFIG);
> > @@ -7762,6 +7770,7 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
> >           virObjectUnlock(vm);
> >       virObjectUnref(caps);
> >       virObjectUnref(cfg);
> > +    virNWFilterUnlockFilterUpdates();
> >       return ret;
> >   }
> >
> > @@ -14503,6 +14512,8 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> >        * and use of FORCE can cause multiple transitions.
> >        */
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       if (!(vm = qemuDomObjFromSnapshot(snapshot)))
> >           return -1;
> >
> > @@ -14824,6 +14835,7 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> >           virObjectUnlock(vm);
> >       virObjectUnref(caps);
> >       virObjectUnref(cfg);
> > +    virNWFilterUnlockFilterUpdates();
> >
> >       return ret;
> >   }
> > diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> > index c797206..533bb35 100644
> > --- a/src/qemu/qemu_migration.c
> > +++ b/src/qemu/qemu_migration.c
> > @@ -2525,6 +2525,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
> >       if (virTimeMillisNow(&now) < 0)
> >           return -1;
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       if (flags & VIR_MIGRATE_OFFLINE) {
> >           if (flags & (VIR_MIGRATE_NON_SHARED_DISK |
> >                        VIR_MIGRATE_NON_SHARED_INC)) {
> > @@ -2826,6 +2828,7 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
> >           qemuDomainEventQueue(driver, event);
> >       qemuMigrationCookieFree(mig);
> >       virObjectUnref(caps);
> > +    virNWFilterUnlockFilterUpdates();
> >       return ret;
> >
> >    stop:
> > diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> > index 24e5f0f..0078a70 100644
> > --- a/src/qemu/qemu_process.c
> > +++ b/src/qemu/qemu_process.c
> > @@ -3438,6 +3438,8 @@ qemuProcessReconnect(void *opaque)
> >
> >       VIR_FREE(data);
> >
> > +    virNWFilterReadLockFilterUpdates();
> > +
> >       virObjectLock(obj);
> >
> >       cfg = virQEMUDriverGetConfig(driver);
> > @@ -3589,6 +3591,7 @@ qemuProcessReconnect(void *opaque)
> >
> >       virObjectUnref(conn);
> >       virObjectUnref(cfg);
> > +    virNWFilterUnlockFilterUpdates();
> >
> >       return;
> >
> > @@ -3624,6 +3627,7 @@ qemuProcessReconnect(void *opaque)
> >       }
> >       virObjectUnref(conn);
> >       virObjectUnref(cfg);
> > +    virNWFilterUnlockFilterUpdates();
> >   }
> >
> >   static int

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