mcctrl_ikc_send_wait: give possibility to use pre-allocated desc

Change-Id: I1afbabe792648bbf2c5a9a38ebbfba8ea9060d06

executer/kernel/mcctrl/control.c

@@ -189,8 +189,8 @@ static long mcexec_prepare_image(ihk_os_t os,
 	dprintk("# of sections: %d\n", pdesc->num_sections);
 	dprintk("%p (%lx)\n", pdesc, isp.arg);
 
-	ret = mcctrl_ikc_send_wait(os, pdesc->cpu, &isp, 0, &free_ikc_pointers,
+	ret = mcctrl_ikc_send_wait(os, pdesc->cpu, &isp, 0, NULL,
-				   3, pdesc, args, envs);
+				   &free_ikc_pointers, 3, pdesc, args, envs);
 	if (ret < 0) {
 		/* either send or remote prepare_process failed */
 		goto put_and_free_out;

executer/kernel/mcctrl/ikc.c

@@ -57,15 +57,6 @@ void mcctrl_os_read_write_cpu_response(ihk_os_t os,
 		struct ikc_scd_packet *pisp);
 void mcctrl_eventfd(ihk_os_t os, struct ikc_scd_packet *pisp);
 
-struct mcctrl_wakeup_desc {
-	int status;
-	int err;
-	wait_queue_head_t wq;
-	struct list_head chain;
-	int free_addrs_count;
-	void *free_addrs[];
-};
-
 /* Assumes usrdata->wakeup_descs_lock taken */
 static void mcctrl_wakeup_desc_cleanup(ihk_os_t os,
 		struct mcctrl_wakeup_desc *desc)
@@ -109,13 +100,15 @@ static void mcctrl_wakeup_cb(ihk_os_t os, struct ikc_scd_packet *packet)
 }
 
 int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
-		long int timeout, int *do_frees, int free_addrs_count, ...)
+		long int timeout, struct mcctrl_wakeup_desc *desc,
+		int *do_frees, int free_addrs_count, ...)
 {
 	int ret, i;
+	int alloc_desc = (desc == NULL);
 	va_list ap;
-	struct mcctrl_wakeup_desc *desc;
 
 	*do_frees = 1;
+	if (alloc_desc)
 		desc = kmalloc(sizeof(struct mcctrl_wakeup_desc) +
 			       (free_addrs_count + 1) * sizeof(void *),
 			       GFP_KERNEL);
@@ -128,9 +121,10 @@ int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
 	for (i = 0; i < free_addrs_count; i++) {
 		desc->free_addrs[i] = va_arg(ap, void*);
 	}
-	desc->free_addrs[free_addrs_count] = desc;
 	va_end(ap);
-	desc->free_addrs_count = free_addrs_count + 1;
+	if (alloc_desc)
+		desc->free_addrs[free_addrs_count++] = desc;
+	desc->free_addrs_count = free_addrs_count;
 	init_waitqueue_head(&desc->wq);
 	WRITE_ONCE(desc->err, 0);
 	WRITE_ONCE(desc->status, 0);
@@ -165,6 +159,7 @@ int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
 	}
 
 	ret = READ_ONCE(desc->err);
+	if (alloc_desc)
 		kfree(desc);
 	return ret;
 }

executer/kernel/mcctrl/mcctrl.h

@@ -369,9 +369,33 @@ int mcctrl_ikc_send(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp);
 int mcctrl_ikc_send_msg(ihk_os_t os, int cpu, int msg, int ref, unsigned long arg);
 int mcctrl_ikc_is_valid_thread(ihk_os_t os, int cpu);
 
-/* ikc query-and-wait helper */
+struct mcctrl_wakeup_desc {
+	int status;
+	int err;
+	wait_queue_head_t wq;
+	struct list_head chain;
+	int free_addrs_count;
+	void *free_addrs[];
+};
+
+/* ikc query-and-wait helper
+ *
+ * Arguments:
+ *  - os, cpu and pisp as per mcctl_ikc_send()
+ *  - timeout: time to wait for reply in ms
+ *  - desc: if set, memory area to be used for desc.
+ *    Care must be taken to leave room for variable-length array.
+ *  - do_free: returns bool that specify if the caller should free
+ *    its memory on error (e.g. if ikc_send failed in the first place,
+ *    the reply has no chance of coming and memory should be free)
+ *    Always true on success.
+ *  - free_addrs_count & ...: addresses to kmalloc'd pointers that
+ *    are referenced in the message and must be left intact if we
+ *    abort to timeout/signal.
+ */
 int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
-	long int timeout, int *do_frees, int free_addrs_count, ...);
+	long int timeout, struct mcctrl_wakeup_desc *desc,
+	int *do_frees, int free_addrs_count, ...);
 
 ihk_os_t osnum_to_os(int n);