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Subject[PATCH 2/2] ehea: fix possible DLPAR/mem deadlock
Force serialization of userspace-triggered DLPAR/mem operations

Signed-off-by: Thomas Klein <tklein@de.ibm.com>
---
Patch created against 2.6.34-rc4

diff -Nurp linux-2.6.34-rc4.orig//drivers/net/ehea/ehea.h linux-2.6.34-rc4//drivers/net/ehea/ehea.h
--- linux-2.6.34-rc4.orig//drivers/net/ehea/ehea.h 2010-04-19 11:54:07.000000000 +0200
+++ linux-2.6.34-rc4//drivers/net/ehea/ehea.h 2010-04-19 12:00:14.000000000 +0200
@@ -40,7 +40,7 @@
#include <asm/io.h>

#define DRV_NAME "ehea"
-#define DRV_VERSION "EHEA_0102"
+#define DRV_VERSION "EHEA_0103"

/* eHEA capability flags */
#define DLPAR_PORT_ADD_REM 1
diff -Nurp linux-2.6.34-rc4.orig//drivers/net/ehea/ehea_main.c linux-2.6.34-rc4//drivers/net/ehea/ehea_main.c
--- linux-2.6.34-rc4.orig//drivers/net/ehea/ehea_main.c 2010-04-19 11:59:11.000000000 +0200
+++ linux-2.6.34-rc4//drivers/net/ehea/ehea_main.c 2010-04-19 11:59:50.000000000 +0200
@@ -2889,7 +2889,6 @@ static void ehea_rereg_mrs(struct work_s
int ret, i;
struct ehea_adapter *adapter;

- mutex_lock(&dlpar_mem_lock);
ehea_info("LPAR memory changed - re-initializing driver");

list_for_each_entry(adapter, &adapter_list, list)
@@ -2959,7 +2958,6 @@ static void ehea_rereg_mrs(struct work_s
}
ehea_info("re-initializing driver complete");
out:
- mutex_unlock(&dlpar_mem_lock);
return;
}

@@ -3542,7 +3540,14 @@ void ehea_crash_handler(void)
static int ehea_mem_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
+ int ret = NOTIFY_BAD;
struct memory_notify *arg = data;
+
+ if (!mutex_trylock(&dlpar_mem_lock)) {
+ ehea_info("ehea_mem_notifier must not be called parallelized");
+ goto out;
+ }
+
switch (action) {
case MEM_CANCEL_OFFLINE:
ehea_info("memory offlining canceled");
@@ -3551,14 +3556,14 @@ static int ehea_mem_notifier(struct noti
ehea_info("memory is going online");
set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
if (ehea_add_sect_bmap(arg->start_pfn, arg->nr_pages))
- return NOTIFY_BAD;
+ goto out_unlock;
ehea_rereg_mrs(NULL);
break;
case MEM_GOING_OFFLINE:
ehea_info("memory is going offline");
set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
if (ehea_rem_sect_bmap(arg->start_pfn, arg->nr_pages))
- return NOTIFY_BAD;
+ goto out_unlock;
ehea_rereg_mrs(NULL);
break;
default:
@@ -3566,8 +3571,12 @@ static int ehea_mem_notifier(struct noti
}

ehea_update_firmware_handles();
+ ret = NOTIFY_OK;

- return NOTIFY_OK;
+out_unlock:
+ mutex_unlock(&dlpar_mem_lock);
+out:
+ return ret;
}

static struct notifier_block ehea_mem_nb = {

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