[PATCH 05/07]
This patche makes the memory hotplug chain's mutex held for a shorter time:
when memory is offlined or onlined a work item is added to the global
workqueue.
When the work item is run, it notifies the ipcns notifier chain with the
IPCNS_MEMCHANGED event.
Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
---
ipc/util.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
Index: linux-2.6.24/ipc/util.c
===================================================================
--- linux-2.6.24.orig/ipc/util.c 2008-01-31 11:04:51.000000000 +0100
+++ linux-2.6.24/ipc/util.c 2008-01-31 11:41:01.000000000 +0100
@@ -57,6 +57,14 @@ atomic_t nr_ipc_ns = ATOMIC_INIT(1);
#ifdef CONFIG_MEMORY_HOTPLUG
+static void ipc_memory_notifier(struct work_struct *work)
+{
+ ipcns_notify(IPCNS_MEMCHANGED);
+}
+
+static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
+
+
static int ipc_memory_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
@@ -65,9 +73,14 @@ static int ipc_memory_callback(struct no
case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
/*
* This is done by invoking the ipcns notifier chain with the
- * IPC_MEMCHANGED event
+ * IPC_MEMCHANGED event.
+ * In order not to keep the lock on the hotplug memory chain
+ * for too long, queue a work item that will, when waken up,
+ * activate the ipcns notification chain.
+ * No need to keep several ipc work items on the queue.
*/
- ipcns_notify(IPCNS_MEMCHANGED);
+ if (!work_pending(&ipc_memory_wq))
+ schedule_work(&ipc_memory_wq);
break;
case MEM_GOING_ONLINE:
case MEM_GOING_OFFLINE:
--
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