env: add spdk_env_fini()

The function now has to be called before application
exit. At the moment it only frees the dynamically
allocated DPDK command line option strings - something
that was previously done from an atexit() callback -
but there's more to free there.

Note: the function descriptions were partially copied
from equivalent DPDK functions.

Change-Id: I5f4a6607fdfadff9325917259f58fcbc2cedba1a
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/447676
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

CHANGELOG.md

@@ -61,6 +61,12 @@ For retrieving physical addresses, spdk_vtophys() should be used instead.
 
 Dropped support for DPDK 17.07 and earlier, which SPDK won't even compile with right now.
 
+### env
+
+spdk_env_fini() and spdk_env_dpdk_post_fini() were added to release any resources
+allocated by spdk_env_init() or spdk_env_dpdk_post_init() respectively. It is expected
+that common usage of those functions is to call them just before terminating the process.
+
 ## v19.01:
 
 ### ocf bdev

include/spdk/env.h

@@ -168,6 +168,14 @@ void spdk_env_opts_init(struct spdk_env_opts *opts);
  */
 int spdk_env_init(const struct spdk_env_opts *opts);
 
+/**
+ * Release any resources of the environment library that were alllocated with
+ * spdk_env_init(). After this call, no SPDK env function calls may be made.
+ * It is expected that common usage of this function is to call it just before
+ * terminating the process.
+ */
+void spdk_env_fini(void);
+
 /**
  * Allocate a pinned memory buffer with the given size and alignment.
  *

include/spdk/env_dpdk.h

@@ -52,6 +52,14 @@ extern "C" {
  */
 int spdk_env_dpdk_post_init(void);
 
+/**
+ * Release any resources of the environment library that were alllocated with
+ * spdk_env_dpdk_post_init(). After this call, no DPDK function calls may
+ * be made. It is expected that common usage of this function is to call it
+ * just before terminating the process.
+ */
+void spdk_env_dpdk_post_fini(void);
+
 /**
  * Check if DPDK was initialized external to the SPDK env_dpdk library.
  *

lib/env_dpdk/init.c

@@ -174,13 +174,6 @@ spdk_push_arg(char *args[], int *argcount, char *arg)
 	return tmp;
 }
 
-static void
-spdk_destruct_eal_cmdline(void)
-{
-	spdk_free_args(g_eal_cmdline, g_eal_cmdline_argcount);
-}
-
-
 static int
 spdk_build_eal_cmdline(const struct spdk_env_opts *opts)
 {
@@ -365,10 +358,6 @@ spdk_build_eal_cmdline(const struct spdk_env_opts *opts)
 
 	g_eal_cmdline = args;
 	g_eal_cmdline_argcount = argcount;
-	if (atexit(spdk_destruct_eal_cmdline) != 0) {
-		fprintf(stderr, "Failed to register cleanup handler\n");
-	}
-
 	return argcount;
 }
 
@@ -389,6 +378,12 @@ spdk_env_dpdk_post_init(void)
 	return 0;
 }
 
+void
+spdk_env_dpdk_post_fini(void)
+{
+	spdk_free_args(g_eal_cmdline, g_eal_cmdline_argcount);
+}
+
 int
 spdk_env_init(const struct spdk_env_opts *opts)
 {
@@ -449,6 +444,12 @@ spdk_env_init(const struct spdk_env_opts *opts)
 	return spdk_env_dpdk_post_init();
 }
 
+void
+spdk_env_fini(void)
+{
+	spdk_env_dpdk_post_fini();
+}
+
 bool
 spdk_env_dpdk_external_init(void)
 {

lib/event/app.c

@@ -696,6 +696,7 @@ spdk_app_fini(void)
 {
 	spdk_trace_cleanup();
 	spdk_reactors_fini();
+	spdk_env_fini();
 	spdk_conf_free(g_spdk_app.config);
 	spdk_log_close();
 }