On 5/28/19 10:32 AM, Huaqiang,Wang wrote:
On 2019年05月27日 23:26, Michal Privoznik wrote:
On 5/23/19 11:34 AM, Wang Huaqiang wrote:
Export virResctrlMonitorGetStats and make
virResctrlMonitorGetCacheOccupancy obsoleted.
Signed-off-by: Wang Huaqiang <huaqiang.wang@xxxxxxxxx>
---
src/libvirt_private.syms | 1 +
src/qemu/qemu_driver.c | 33 +++++++++++++++++++++++++--------
src/util/virresctrl.c | 46
+++++++++++++++++++++++++++-------------------
src/util/virresctrl.h | 6 ++++++
4 files changed, 59 insertions(+), 27 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 9099757..2e3d48c 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2771,6 +2771,7 @@ virResctrlMonitorDeterminePath;
virResctrlMonitorFreeStats;
virResctrlMonitorGetCacheOccupancy;
virResctrlMonitorGetID;
+virResctrlMonitorGetStats;
virResctrlMonitorNew;
virResctrlMonitorRemove;
virResctrlMonitorSetAlloc;
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 4ea346c..bc19171 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -19987,6 +19987,7 @@
qemuDomainFreeResctrlMonData(virQEMUResctrlMonDataPtr resdata)
/**
* qemuDomainGetResctrlMonData:
+ * @driver: Pointer to qemu driver
* @dom: Pointer for the domain that the resctrl monitors reside in
* @resdata: Pointer of virQEMUResctrlMonDataPtr pointer for
receiving the
* virQEMUResctrlMonDataPtr array. Caller is responsible
for
@@ -20005,16 +20006,29 @@
qemuDomainFreeResctrlMonData(virQEMUResctrlMonDataPtr resdata)
* Returns -1 on failure, or 0 on success.
*/
static int
-qemuDomainGetResctrlMonData(virDomainObjPtr dom,
+qemuDomainGetResctrlMonData(virQEMUDriverPtr driver,
+ virDomainObjPtr dom,
virQEMUResctrlMonDataPtr **resdata,
size_t *nresdata,
virResctrlMonitorType tag)
{
virDomainResctrlDefPtr resctrl = NULL;
virQEMUResctrlMonDataPtr res = NULL;
+ char **features = NULL;
size_t i = 0;
size_t j = 0;
+ if (tag == VIR_RESCTRL_MONITOR_TYPE_CACHE) {
+ features = driver->caps->host.cache.monitor->features;
No, we have virQEMUDriverGetCapabilities() which ensures that
driver->caps object doesn't go away while accessing this.
I can't refer 'driver->caps->host.cache.monitor->features' directly
because this function (qemuDomainGetResctrlMonData)
will be used for 'memory bandwidth' monitors also.
at that time that the piece of code looks like:
+ if (tag == VIR_RESCTRL_MONITOR_TYPE_CACHE) {
+ if (driver->caps->host.cache.monitor)
+ features = driver->caps->host.cache.monitor->features;
+ if (tag == VIR_RESCTRL_MONITOR_TYPE_MEMBW) {
+ if(driver->caps->host.membw)
+ features = driver->caps->host.membw.monitor->features;
What I meant is that you can obtain virCaps object and then access it
instead:
virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false);
if (tag == VIR_RES..)
features = caps->host.cache.monitor->features;
It's not safe to access driver->caps directly because another thread
might refresh those meanwhile. What may happen for instance is the
following:
Thread1:
fetches driver pointer
adds ->caps displacement
fetches value from that address (which is a long way of saying 'fetch
driver->caps')
Thread2:
Executes virQEMUDriverGetCapabilities(), which boils down to:
virObjectUnref(driver->caps);
driver->caps = caps;
Thread1:
resumes execution and tries to access ->host member.
This is where Thread1 would be accessing invalid memory because the
memory it's trying to access was freed meanwhile by Thread2.
Michal
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list
