eal/linux: allow multiple starts of event monitor

In some cases, a device or infrastructure may want to enable hotplug
but application may also try and start hotplug as well. Therefore
change the monitor_started from a boolean into a reference count.

Signed-off-by: Long Li <longli@microsoft.com>

diff --git a/lib/librte_eal/linux/eal_dev.c b/lib/librte_eal/linux/eal_dev.c
index 5c0e752..3b905e1 100644 (file)
--- a/lib/librte_eal/linux/eal_dev.c
+++ b/lib/librte_eal/linux/eal_dev.c
@@ -23,8 +23,12 @@
 
 #include "eal_private.h"
 
-static struct rte_intr_handle intr_handle = {.fd = -1 };
-static bool monitor_started;
+static struct rte_intr_handle intr_handle = {
+       .type = RTE_INTR_HANDLE_DEV_EVENT,
+       .fd = -1,
+};
+static rte_rwlock_t monitor_lock = RTE_RWLOCK_INITIALIZER;
+static uint32_t monitor_refcount;
 static bool hotplug_handle;
 
 #define EAL_UEV_MSG_LEN 4096
@@ -298,50 +302,70 @@ failure_handle_err:
 int
 rte_dev_event_monitor_start(void)
 {
-       int ret;
+       int ret = 0;
 
-       if (monitor_started)
-               return 0;
+       rte_rwlock_write_lock(&monitor_lock);
+
+       if (monitor_refcount) {
+               monitor_refcount++;
+               goto exit;
+       }
 
        ret = dev_uev_socket_fd_create();
        if (ret) {
                RTE_LOG(ERR, EAL, "error create device event fd.\n");
-               return -1;
+               goto exit;
        }
 
-       intr_handle.type = RTE_INTR_HANDLE_DEV_EVENT;
        ret = rte_intr_callback_register(&intr_handle, dev_uev_handler, NULL);
 
        if (ret) {
                RTE_LOG(ERR, EAL, "fail to register uevent callback.\n");
-               return -1;
+               close(intr_handle.fd);
+               intr_handle.fd = -1;
+               goto exit;
        }
 
-       monitor_started = true;
+       monitor_refcount++;
 
-       return 0;
+exit:
+       rte_rwlock_write_unlock(&monitor_lock);
+       return ret;
 }
 
 int
 rte_dev_event_monitor_stop(void)
 {
-       int ret;
+       int ret = 0;
 
-       if (!monitor_started)
-               return 0;
+       rte_rwlock_write_lock(&monitor_lock);
+
+       if (!monitor_refcount) {
+               RTE_LOG(ERR, EAL, "device event monitor already stopped\n");
+               goto exit;
+       }
+
+       if (monitor_refcount > 1) {
+               monitor_refcount--;
+               goto exit;
+       }
 
        ret = rte_intr_callback_unregister(&intr_handle, dev_uev_handler,
                                           (void *)-1);
        if (ret < 0) {
                RTE_LOG(ERR, EAL, "fail to unregister uevent callback.\n");
-               return ret;
+               goto exit;
        }
 
        close(intr_handle.fd);
        intr_handle.fd = -1;
-       monitor_started = false;
 
-       return 0;
+       monitor_refcount--;
+
+exit:
+       rte_rwlock_write_unlock(&monitor_lock);
+
+       return ret;
 }
 
 int