app/testpmd: workaround deadlock in hot-unplug callback

Because the user's callback is invoked in eal interrupt callback, the
interrupt callback need to be finished before it can be unregistered
when detaching device. So finish callback soon and use a deferred
removal to detach device is need.

It is a workaround, once the device detaching be moved into the eal in
the future, the deferred removal could be deleted. This patch aim to
add this workaround and refine the function name and the description to
be more explicit and comment the limitation.

Fixes: 2049c5113fe8 ("app/testpmd: use hotplug failure handler")
Signed-off-by: Jeff Guo <jia.guo@intel.com>

diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index 9c0edcaed12f614be18678825d935e3a6618c389..4c75587d0fe59d662fc283d96f81717354de671b 100644 (file)
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -506,7 +506,7 @@ static void check_all_ports_link_status(uint32_t port_mask);
 static int eth_event_callback(portid_t port_id,
                              enum rte_eth_event_type type,
                              void *param, void *ret_param);
-static void eth_dev_event_callback(const char *device_name,
+static void dev_event_callback(const char *device_name,
                                enum rte_dev_event_type type,
                                void *param);
 
@@ -2434,7 +2434,7 @@ pmd_test_exit(void)
                }
 
                ret = rte_dev_event_callback_unregister(NULL,
-                       eth_dev_event_callback, NULL);
+                       dev_event_callback, NULL);
                if (ret < 0) {
                        RTE_LOG(ERR, EAL,
                                "fail to unregister device event callback.\n");
@@ -2516,8 +2516,14 @@ check_all_ports_link_status(uint32_t port_mask)
        }
 }
 
+/*
+ * This callback is for remove a port for a device. It has limitation because
+ * it is not for multiple port removal for a device.
+ * TODO: the device detach invoke will plan to be removed from user side to
+ * eal. And convert all PMDs to free port resources on ether device closing.
+ */
 static void
-rmv_event_callback(void *arg)
+rmv_port_callback(void *arg)
 {
        int need_to_start = 0;
        int org_no_link_check = no_link_check;
@@ -2565,7 +2571,7 @@ eth_event_callback(portid_t port_id, enum rte_eth_event_type type, void *param,
                if (port_id_is_invalid(port_id, DISABLED_WARN))
                        break;
                if (rte_eal_alarm_set(100000,
-                               rmv_event_callback, (void *)(intptr_t)port_id))
+                               rmv_port_callback, (void *)(intptr_t)port_id))
                        fprintf(stderr, "Could not set up deferred device removal\n");
                break;
        default:
@@ -2598,7 +2604,7 @@ register_eth_event_callback(void)
 
 /* This function is used by the interrupt thread */
 static void
-eth_dev_event_callback(const char *device_name, enum rte_dev_event_type type,
+dev_event_callback(const char *device_name, enum rte_dev_event_type type,
                             __rte_unused void *arg)
 {
        uint16_t port_id;
@@ -2612,7 +2618,7 @@ eth_dev_event_callback(const char *device_name, enum rte_dev_event_type type,
 
        switch (type) {
        case RTE_DEV_EVENT_REMOVE:
-               RTE_LOG(ERR, EAL, "The device: %s has been removed!\n",
+               RTE_LOG(DEBUG, EAL, "The device: %s has been removed!\n",
                        device_name);
                ret = rte_eth_dev_get_port_by_name(device_name, &port_id);
                if (ret) {
@@ -2620,7 +2626,19 @@ eth_dev_event_callback(const char *device_name, enum rte_dev_event_type type,
                                device_name);
                        return;
                }
-               rmv_event_callback((void *)(intptr_t)port_id);
+               /*
+                * Because the user's callback is invoked in eal interrupt
+                * callback, the interrupt callback need to be finished before
+                * it can be unregistered when detaching device. So finish
+                * callback soon and use a deferred removal to detach device
+                * is need. It is a workaround, once the device detaching be
+                * moved into the eal in the future, the deferred removal could
+                * be deleted.
+                */
+               if (rte_eal_alarm_set(100000,
+                               rmv_port_callback, (void *)(intptr_t)port_id))
+                       RTE_LOG(ERR, EAL,
+                               "Could not set up deferred device removal\n");
                break;
        case RTE_DEV_EVENT_ADD:
                RTE_LOG(ERR, EAL, "The device: %s has been added!\n",
@@ -3167,7 +3185,7 @@ main(int argc, char** argv)
                }
 
                ret = rte_dev_event_callback_register(NULL,
-                       eth_dev_event_callback, NULL);
+                       dev_event_callback, NULL);
                if (ret) {
                        RTE_LOG(ERR, EAL,
                                "fail  to register device event callback\n");