104 lines
3.4 KiB
Diff
104 lines
3.4 KiB
Diff
From cab81502320d97dac4c5c12e7496f30896709c49 Mon Sep 17 00:00:00 2001
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From: Matthias Bolte <matthias.bolte@googlemail.com>
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Date: Tue, 22 Sep 2009 15:12:48 +0200
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Subject: [PATCH] Fix xen driver refcounting.
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The commit cb51aa48a777ddae6997faa9f28350cb62655ffd "Fix up connection
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reference counting." changed the driver closing and virConnectPtr
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unref-logic in virConnectClose().
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Before this commit virConnectClose() closed all drivers of the given
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virConnectPtr and virUnrefConnect()'ed it afterwards. After this
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commit the driver-closing is done in virUnrefConnect() if and only if
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the ref-count of the virConnectPtr dropped to zero.
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This change in execution order leads to a virConnectPtr leak, at least
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for connections to Xen.
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The relevant call sequences:
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virConnectOpen() -> xenUnifiedOpen() ...
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... xenInotifyOpen() -> virConnectRef(conn)
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... xenStoreOpen() -> xenStoreAddWatch() -> conn->refs++
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virConnectClose() -> xenUnifiedClose() ...
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... xenInotifyClose() -> virUnrefConnect(conn)
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... xenStoreClose() -> xenStoreRemoveWatch() -> virUnrefConnect(conn)
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Before the commit this additional virConnectRef/virUnrefConnect calls
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where no problem, because virConnectClose() closed the drivers
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explicitly and the additional refs added by the Xen subdrivers were
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removed properly. After the commit this additional refs result in a
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virConnectPtr leak (including a leak of the hypercall file handle;
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that's how I noticed this problem), because now the drivers are only
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close if and only if the ref-count drops to zero, but this cannot
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happen anymore, because the additional refs from the Xen subdrivers
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would only be removed if the drivers get closed, but that doesn't
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happen because the ref-count cannot drop to zero.
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The fix for this problem is simple: remove the
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virConnectRef/virUnrefConnect calls from the Xen subdrivers (see
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attached patch). Maybe someone could explain why the Xen Inotify and
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Xen Store driver do this extra ref-counting, but none of the other Xen
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subdrivers. It seems unnecessary to me and can be removed without
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problems.
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Signed-off-by: Chris Lalancette <clalance@redhat.com>
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(cherry picked from commit 6ed7374c5a6c6a2b1b1801d7d041dc7f09748592)
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Fedora-patch: libvirt-fix-xen-driver-refcounting.patch
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---
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src/xen_inotify.c | 2 --
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src/xs_internal.c | 3 ---
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2 files changed, 0 insertions(+), 5 deletions(-)
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diff --git a/src/xen_inotify.c b/src/xen_inotify.c
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index e312b9e..ecaefaf 100644
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--- a/src/xen_inotify.c
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+++ b/src/xen_inotify.c
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@@ -463,7 +463,6 @@ xenInotifyOpen(virConnectPtr conn ATTRIBUTE_UNUSED,
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DEBUG0("Failed to add inotify handle, disabling events");
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}
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- virConnectRef(conn);
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return 0;
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}
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@@ -486,7 +485,6 @@ xenInotifyClose(virConnectPtr conn)
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if (priv->inotifyWatch != -1)
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virEventRemoveHandle(priv->inotifyWatch);
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close(priv->inotifyFD);
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- virUnrefConnect(conn);
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return 0;
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}
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diff --git a/src/xs_internal.c b/src/xs_internal.c
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index 1f54b1f..a18dcad 100644
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--- a/src/xs_internal.c
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+++ b/src/xs_internal.c
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@@ -1139,8 +1139,6 @@ int xenStoreAddWatch(virConnectPtr conn,
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list->watches[n] = watch;
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list->count++;
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- conn->refs++;
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-
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return xs_watch(priv->xshandle, watch->path, watch->token);
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}
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@@ -1190,7 +1188,6 @@ int xenStoreRemoveWatch(virConnectPtr conn,
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; /* Failure to reduce memory allocation isn't fatal */
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}
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list->count--;
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- virUnrefConnect(conn);
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return 0;
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}
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}
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--
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1.6.2.5
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