[PATCH v4] lib/eal: fix segfaults due to thread exit order

[zhichaox.zeng@intel.com]

From: Zhichao Zeng <zhichaox.zeng@intel.com>

The eal-intr-thread is not closed before memory cleanup in the
process of exiting. There is a small probability that when the
eal-intr-thread is about to use some pointers, the memory were
just cleaned, which cause the segment fault error caught by ASan.

This patch close the eal-intr-thread before memory cleanup when
exiting to avoid segment fault. And add some atomic operations
to avoid executing rte_eal_cleanup in the child process spawned
by fork() in some test cases, e.g. debug_autotest of dpdk-test.

Cc: stable@dpdk.org

---
v2:
add the same API for FreeBSD
---
v3:
fix rte_eal_cleanup crash in debug_autotest
---
v4:
shorten the prompt message and optimize the commit log

Suggested-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
---
 lib/eal/common/eal_private.h     |  7 +++++++
 lib/eal/freebsd/eal.c            | 21 ++++++++++++++++++++-
 lib/eal/freebsd/eal_interrupts.c | 12 ++++++++++++
 lib/eal/linux/eal.c              | 20 +++++++++++++++++++-
 lib/eal/linux/eal_interrupts.c   | 12 ++++++++++++
 5 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
index 44d14241f0..7adf41b7d7 100644
--- a/lib/eal/common/eal_private.h
+++ b/lib/eal/common/eal_private.h
@@ -152,6 +152,13 @@ int rte_eal_tailqs_init(void);
  */
 int rte_eal_intr_init(void);
 
+/**
+ * Destroy interrupt handling thread.
+ *
+ * This function is private to EAL.
+ */
+void rte_eal_intr_destroy(void);
+
 /**
  * Close the default log stream
  *
diff --git a/lib/eal/freebsd/eal.c b/lib/eal/freebsd/eal.c
index a6b20960f2..4882f27abd 100644
--- a/lib/eal/freebsd/eal.c
+++ b/lib/eal/freebsd/eal.c
@@ -72,6 +72,8 @@ struct lcore_config lcore_config[RTE_MAX_LCORE];
 /* used by rte_rdtsc() */
 int rte_cycles_vmware_tsc_map;
 
+/* used to judge the running status of the eal */
+static uint32_t run_once;
 
 int
 eal_clean_runtime_dir(void)
@@ -574,12 +576,22 @@ static void rte_eal_init_alert(const char *msg)
 	RTE_LOG(ERR, EAL, "%s\n", msg);
 }
 
+static void warn_parent(void)
+{
+	RTE_LOG(WARNING, EAL, "DPDK won't work in the child process\n");
+}
+
+static void scratch_child(void)
+{
+	/* Scratch run_once so that a call to rte_eal_cleanup won't crash... */
+	__atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
+}
+
 /* Launch threads, called at application init(). */
 int
 rte_eal_init(int argc, char **argv)
 {
 	int i, fctret, ret;
-	static uint32_t run_once;
 	uint32_t has_run = 0;
 	char cpuset[RTE_CPU_AFFINITY_STR_LEN];
 	char thread_name[RTE_MAX_THREAD_NAME_LEN];
@@ -883,6 +895,8 @@ rte_eal_init(int argc, char **argv)
 
 	eal_mcfg_complete();
 
+	pthread_atfork(NULL, warn_parent, scratch_child);
+
 	return fctret;
 }
 
@@ -891,8 +905,13 @@ rte_eal_cleanup(void)
 {
 	struct internal_config *internal_conf =
 		eal_get_internal_configuration();
+
+	if (__atomic_load_n(&run_once, __ATOMIC_RELAXED) == 0)
+		return 0;
+
 	rte_service_finalize();
 	rte_mp_channel_cleanup();
+	rte_eal_intr_destroy();
 	/* after this point, any DPDK pointers will become dangling */
 	rte_eal_memory_detach();
 	rte_eal_alarm_cleanup();
diff --git a/lib/eal/freebsd/eal_interrupts.c b/lib/eal/freebsd/eal_interrupts.c
index 9f720bdc8f..cac3859b06 100644
--- a/lib/eal/freebsd/eal_interrupts.c
+++ b/lib/eal/freebsd/eal_interrupts.c
@@ -648,6 +648,18 @@ rte_eal_intr_init(void)
 	return ret;
 }
 
+void
+rte_eal_intr_destroy(void)
+{
+	/* cancel the host thread to wait/handle the interrupt */
+	pthread_cancel(intr_thread);
+	pthread_join(intr_thread, NULL);
+
+	/* close kqueue */
+	close(kq);
+	kq = -1;
+}
+
 int
 rte_intr_rx_ctl(struct rte_intr_handle *intr_handle,
 		int epfd, int op, unsigned int vec, void *data)
diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
index 1ef263434a..effebb33a6 100644
--- a/lib/eal/linux/eal.c
+++ b/lib/eal/linux/eal.c
@@ -76,6 +76,8 @@ struct lcore_config lcore_config[RTE_MAX_LCORE];
 /* used by rte_rdtsc() */
 int rte_cycles_vmware_tsc_map;
 
+/* used to judge the running status of the eal */
+static uint32_t run_once;
 
 int
 eal_clean_runtime_dir(void)
@@ -857,12 +859,22 @@ is_iommu_enabled(void)
 	return n > 2;
 }
 
+static void warn_parent(void)
+{
+	RTE_LOG(WARNING, EAL, "DPDK won't work in the child process\n");
+}
+
+static void scratch_child(void)
+{
+	/* Scratch run_once so that a call to rte_eal_cleanup won't crash... */
+	__atomic_store_n(&run_once, 0, __ATOMIC_RELAXED);
+}
+
 /* Launch threads, called at application init(). */
 int
 rte_eal_init(int argc, char **argv)
 {
 	int i, fctret, ret;
-	static uint32_t run_once;
 	uint32_t has_run = 0;
 	const char *p;
 	static char logid[PATH_MAX];
@@ -1228,6 +1240,8 @@ rte_eal_init(int argc, char **argv)
 
 	eal_mcfg_complete();
 
+	pthread_atfork(NULL, warn_parent, scratch_child);
+
 	return fctret;
 }
 
@@ -1257,6 +1271,9 @@ rte_eal_cleanup(void)
 	struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 
+	if (__atomic_load_n(&run_once, __ATOMIC_RELAXED) == 0)
+		return 0;
+
 	if (rte_eal_process_type() == RTE_PROC_PRIMARY &&
 			internal_conf->hugepage_file.unlink_existing)
 		rte_memseg_walk(mark_freeable, NULL);
@@ -1266,6 +1283,7 @@ rte_eal_cleanup(void)
 	vfio_mp_sync_cleanup();
 #endif
 	rte_mp_channel_cleanup();
+	rte_eal_intr_destroy();
 	/* after this point, any DPDK pointers will become dangling */
 	rte_eal_memory_detach();
 	eal_mp_dev_hotplug_cleanup();
diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
index d52ec8eb4c..7e9853e8e7 100644
--- a/lib/eal/linux/eal_interrupts.c
+++ b/lib/eal/linux/eal_interrupts.c
@@ -1199,6 +1199,18 @@ rte_eal_intr_init(void)
 	return ret;
 }
 
+void
+rte_eal_intr_destroy(void)
+{
+	/* cancel the host thread to wait/handle the interrupt */
+	pthread_cancel(intr_thread);
+	pthread_join(intr_thread, NULL);
+
+	/* close the pipe used by epoll */
+	close(intr_pipe.writefd);
+	close(intr_pipe.readfd);
+}
+
 static void
 eal_intr_proc_rxtx_intr(int fd, const struct rte_intr_handle *intr_handle)
 {
-- 
2.25.1