8:28 a.m.
On 09/18/2017 12:34 PM, Erik Skultety wrote:
Adjust udevEventHandleThread to be a proper thread routine running in
an
infinite loop handling devices. Also introduce udevEventThreadData
private structure.
Every time there's and incoming event from udev, udevEventHandleCallback
only increments the number of events queuing on the monitor and signals
the worker thread to handle them.
Signed-off-by: Erik Skultety <eskultet(a)redhat.com>
---
src/node_device/node_device_udev.c | 125 +++++++++++++++++++++++++++++++------
1 file changed, 107 insertions(+), 18 deletions(-)
diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index e144472f1..96760d1e4 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -59,6 +59,54 @@ struct _udevPrivate {
bool privileged;
};
+typedef struct _udevEventThreadData udevEventThreadData;
+typedef udevEventThreadData *udevEventThreadDataPtr;
+
+struct _udevEventThreadData {
+ virMutex lock;
+ virCond threadCond;
+
+ bool threadQuit;
+ int monitor_fd;
+ unsigned long long nevents; /* number of udev events queuing on monitor */
+};
+
+
+static udevEventThreadDataPtr
+udevEventThreadDataNew(int fd)
+{
+ udevEventThreadDataPtr ret = NULL;
+
+ if (VIR_ALLOC_QUIET(ret) < 0)
+ return NULL;
+
+ if (virMutexInit(&ret->lock) < 0)
+ goto cleanup;
+
+ if (virCondInit(&ret->threadCond) < 0)
+ goto cleanup_mutex;
+
+ ret->monitor_fd = fd;
+
+ return ret;
+
+ cleanup_mutex:
+ virMutexDestroy(&ret->lock);
+
+ cleanup:
+ VIR_FREE(ret);
+ return NULL;
+}
+
+
+static void
+udevEventThreadDataFree(udevEventThreadDataPtr data)
+{
+ virMutexDestroy(&data->lock);
+ virCondDestroy(&data->threadCond);
+ VIR_FREE(data);
+}
+
static bool
udevHasDeviceProperty(struct udev_device *dev,
@@ -1648,29 +1696,51 @@ udevEventCheckMonitorFD(struct udev_monitor *udev_monitor,
static void
udevEventHandleThread(void *opaque)
{
+ udevEventThreadDataPtr privateData = opaque;
struct udev_device *device = NULL;
struct udev_monitor *udev_monitor = NULL;
- int fd = (intptr_t) opaque;
- nodeDeviceLock();
- udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
+ /* continue rather than break from the loop on non-fatal errors */
^^
This comment could go to [1]
+ while (1) {
+ virMutexLock(&privateData->lock);
+ while (privateData->nevents == 0 && !privateData->threadQuit) {
+ if (virCondWait(&privateData->threadCond, &privateData->lock))
{
+ virReportSystemError(errno, "%s",
+ _("handler failed to wait on
condition"));
Is a virMutexUnlock required before eventually calling virMutexDestroy...
+ goto cleanup;
+ }
+ }
- if (!udevEventCheckMonitorFD(udev_monitor, fd)) {
+ privateData->nevents--;
+ virMutexUnlock(&privateData->lock);
If we get here, then either nevents > 0 || threadQuit == true, but we
don't check for threadQuit here before the fetch/check of monitor_fd,
e.g. the reason for threadQuit = true, so although the following
udev_monitor check "works", the question thus becomes is it necessary if
threadQuit == true? I suppose it could be, but we could also jump to
cleanup if threadQuit == true || !udevEventCheckMonitorFD
+
+ nodeDeviceLock();
+ udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
+
+ if (!udevEventCheckMonitorFD(udev_monitor, privateData->monitor_fd)) {
This accesses privateData->monitor_fd without the mutex. So we don't
have too many lock/unlock - consider a local @monitor_fd which is
fetched while the lock is held.
+ nodeDeviceUnlock();
+ goto cleanup;
+ }
+
+ device = udev_monitor_receive_device(udev_monitor);
nodeDeviceUnlock();
- return;
- }
- device = udev_monitor_receive_device(udev_monitor);
- nodeDeviceUnlock();
[1] could move the comment here since that's what I believe it's meant
to describe...
+ if (!device) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("udev_monitor_receive_device returned NULL"));
Perhaps a VIR_WARN? Doesn't perhaps really matter, but it's not an error
it's just a condition we didn't expect that we're continuing on...
+ goto next;
This should just be a continue; instead of needing next... Not clear
what happens if udev_device_unref(NULL) is called.
+ }
+
+ udevHandleOneDevice(device);
- if (!device) {
- virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
- _("udev_monitor_receive_device returned NULL"));
- return;
+ next:
+ udev_device_unref(device);
}
- udevHandleOneDevice(device);
+ cleanup:
udev_device_unref(device);
Should this be:
if (device)
udev_device_unref(device)
I think the cleanups are obvious, so
Reviewed-by: John Ferlan <jferlan(a)redhat.com>
John
+ udevEventThreadDataFree(privateData);
+ return;
}
@@ -1678,20 +1748,29 @@ static void
udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
int fd,
int events ATTRIBUTE_UNUSED,
- void *data ATTRIBUTE_UNUSED)
+ void *opaque)
{
struct udev_monitor *udev_monitor = NULL;
+ udevEventThreadDataPtr threadData = opaque;
nodeDeviceLock();
udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
if (!udevEventCheckMonitorFD(udev_monitor, fd)) {
+ virMutexLock(&threadData->lock);
+ threadData->threadQuit = true;
+ virCondSignal(&threadData->threadCond);
+ virMutexUnlock(&threadData->lock);
+
nodeDeviceUnlock();
return;
}
nodeDeviceUnlock();
- udevEventHandleThread((void *)(intptr_t) fd);
+ virMutexLock(&threadData->lock);
+ threadData->nevents++;
+ virCondSignal(&threadData->threadCond);
+ virMutexUnlock(&threadData->lock);
}
@@ -1818,6 +1897,9 @@ nodeStateInitialize(bool privileged,
{
udevPrivate *priv = NULL;
struct udev *udev = NULL;
+ int monitor_fd = -1;
+ virThread th;
+ udevEventThreadDataPtr threadData = NULL;
if (VIR_ALLOC(priv) < 0)
return -1;
@@ -1878,6 +1960,14 @@ nodeStateInitialize(bool privileged,
128 * 1024 * 1024);
#endif
+ monitor_fd = udev_monitor_get_fd(priv->udev_monitor);
+ if (!(threadData = udevEventThreadDataNew(monitor_fd)) ||
+ virThreadCreate(&th, false, udevEventHandleThread, threadData) < 0) {
+ virReportSystemError(errno, "%s",
+ _("failed to create udev handling thread"));
+ goto cleanup;
+ }
+
/* We register the monitor with the event callback so we are
* notified by udev of device changes before we enumerate existing
* devices because libvirt will simply recreate the device if we
@@ -1886,9 +1976,8 @@ nodeStateInitialize(bool privileged,
* enumeration. The alternative is to register the callback after
* we enumerate, in which case we will fail to create any devices
* that appear while the enumeration is taking place. */
- priv->watch = virEventAddHandle(udev_monitor_get_fd(priv->udev_monitor),
- VIR_EVENT_HANDLE_READABLE,
- udevEventHandleCallback, NULL, NULL);
+ priv->watch = virEventAddHandle(monitor_fd, VIR_EVENT_HANDLE_READABLE,
+ udevEventHandleCallback, threadData, NULL);
if (priv->watch == -1)
goto unlock;