[dpdk-dev] [PATCH 2/3] vfio: fix to add handler lock for hot-unplug

[Jeff Guo]

This patch add hot-unplug handler lock and unlock in device request
handler when process bus and device resource, in order to avoid the
synchronization issue when device be hot-unplugged.

Fixes: c115fd000c32 ("vfio: handle hotplug request notifier")
Signed-off-by: Jeff Guo <jia.guo at intel.com>
---
 drivers/bus/pci/linux/pci_vfio.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index 305cc06..d2c8410 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -19,6 +19,7 @@
 #include <rte_vfio.h>
 #include <rte_eal.h>
 #include <rte_bus.h>
+#include <rte_spinlock.h>
 
 #include "eal_filesystem.h"
 
@@ -35,6 +36,14 @@
  * This file is only compiled if CONFIG_RTE_EAL_VFIO is set to "y".
  */
 
+/*
+ * spinlock for device hot-unplug failure handling. If it try to access bus or
+ * device, such as handle sigbus on bus or handle memory failure for device
+ * just need to use this lock. It could protect the bus and the device to avoid
+ * race condition.
+ */
+static rte_spinlock_t failure_handle_lock = RTE_SPINLOCK_INITIALIZER;
+
 #ifdef VFIO_PRESENT
 
 #ifndef PAGE_SIZE
@@ -289,11 +298,12 @@ pci_vfio_req_handler(void *param)
 	int ret;
 	struct rte_device *device = (struct rte_device *)param;
 
+	rte_spinlock_lock(&failure_handle_lock);
 	bus = rte_bus_find_by_device(device);
 	if (bus == NULL) {
 		RTE_LOG(ERR, EAL, "Cannot find bus for device (%s)\n",
 			device->name);
-		return;
+		goto handle_end;
 	}
 
 	/*
@@ -306,6 +316,8 @@ pci_vfio_req_handler(void *param)
 		RTE_LOG(ERR, EAL,
 			"Can not handle hot-unplug for device (%s)\n",
 			device->name);
+handle_end:
+	rte_spinlock_unlock(&failure_handle_lock);
 }
 
 /* enable notifier (only enable req now) */
-- 
2.7.4