Support post-3.13 kthread_create() semantics.

Provide spl_kthread_create() as a wrapper to the kernel's kthread_create()
to provide pre-3.13 semantics.  Re-try if the call is interrupted or if it
would have returned -ENOMEM.  Otherwise return NULL.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #339

include/sys/thread.h

@@ -60,4 +60,32 @@ extern kthread_t *__thread_create(caddr_t stk, size_t  stksize,
                                   int state, pri_t pri);
 extern void __thread_exit(void);
 
+/*
+ * spl_kthread_create - Wrapper providing pre-3.13 semantics for
+ * kthread_create() in which it is not killable and less likely
+ * to return -ENOMEM.
+ */
+static inline struct task_struct *
+spl_kthread_create(int (*func)(void *), void *data, const char namefmt[], ...)
+{
+	struct task_struct *tsk;
+	va_list args;
+
+	va_start(args, namefmt);
+	do {
+		tsk = kthread_create_on_node(func, data,
+			-1, namefmt, args);
+		if (IS_ERR(tsk)) {
+			if (signal_pending(current)) {
+				clear_thread_flag(TIF_SIGPENDING);
+				continue;
+			}
+			if (PTR_ERR(tsk) == -ENOMEM)
+				continue;
+			return (NULL);
+		} else
+			return (tsk);
+	} while (1);
+}
+
 #endif  /* _SPL_THREAD_H */

module/spl/spl-debug.c

@@ -38,6 +38,7 @@
 #include <linux/file_compat.h>
 #include <linux/swap.h>
 #include <sys/sysmacros.h>
+#include <sys/thread.h>
 #include <spl-debug.h>
 #include <spl-trace.h>
 #include <spl-ctl.h>
@@ -415,7 +416,7 @@ spl_debug_dumplog(int flags)
                 spl_debug_dumplog_internal(&dp);
         } else {
 
-                tsk = kthread_create(spl_debug_dumplog_thread,(void *)&dp,"spl_debug");
+                tsk = spl_kthread_create(spl_debug_dumplog_thread,(void *)&dp,"spl_debug");
                 if (tsk == NULL)
                         return -ENOMEM;
 

module/spl/spl-taskq.c

@@ -839,7 +839,7 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 		tqt->tqt_tq = tq;
 		tqt->tqt_id = 0;
 
-		tqt->tqt_thread = kthread_create(taskq_thread, tqt,
+		tqt->tqt_thread = spl_kthread_create(taskq_thread, tqt,
 		    "%s/%d", name, i);
 		if (tqt->tqt_thread) {
 			list_add(&tqt->tqt_thread_list, &tq->tq_thread_list);

module/spl/spl-thread.c

@@ -126,7 +126,7 @@ __thread_create(caddr_t stk, size_t  stksize, thread_func_t func,
 	tp->tp_state = state;
 	tp->tp_pri   = pri;
 
-	tsk = kthread_create(thread_generic_wrapper, (void *)tp,
+	tsk = spl_kthread_create(thread_generic_wrapper, (void *)tp,
 			     "%s", tp->tp_name);
 	if (IS_ERR(tsk)) {
 		SERROR("Failed to create thread: %ld\n", PTR_ERR(tsk));

module/splat/splat-condvar.c

@@ -108,7 +108,7 @@ splat_condvar_test1(struct file *file, void *arg)
 		ct[i].ct_cvp = &cv;
 		ct[i].ct_name = SPLAT_CONDVAR_TEST1_NAME;
 		ct[i].ct_rc = 0;
-		ct[i].ct_thread = kthread_create(splat_condvar_test12_thread,
+		ct[i].ct_thread = spl_kthread_create(splat_condvar_test12_thread,
 		    &ct[i], "%s/%d", SPLAT_CONDVAR_TEST_NAME, i);
 
 		if (!IS_ERR(ct[i].ct_thread)) {
@@ -173,7 +173,7 @@ splat_condvar_test2(struct file *file, void *arg)
 		ct[i].ct_cvp = &cv;
 		ct[i].ct_name = SPLAT_CONDVAR_TEST2_NAME;
 		ct[i].ct_rc = 0;
-		ct[i].ct_thread = kthread_create(splat_condvar_test12_thread,
+		ct[i].ct_thread = spl_kthread_create(splat_condvar_test12_thread,
 		    &ct[i], "%s/%d", SPLAT_CONDVAR_TEST_NAME, i);
 
 		if (!IS_ERR(ct[i].ct_thread)) {
@@ -254,7 +254,7 @@ splat_condvar_test3(struct file *file, void *arg)
 		ct[i].ct_cvp = &cv;
 		ct[i].ct_name = SPLAT_CONDVAR_TEST3_NAME;
 		ct[i].ct_rc = 0;
-		ct[i].ct_thread = kthread_create(splat_condvar_test34_thread,
+		ct[i].ct_thread = spl_kthread_create(splat_condvar_test34_thread,
 		    &ct[i], "%s/%d", SPLAT_CONDVAR_TEST_NAME, i);
 
 		if (!IS_ERR(ct[i].ct_thread)) {
@@ -324,7 +324,7 @@ splat_condvar_test4(struct file *file, void *arg)
 		ct[i].ct_cvp = &cv;
 		ct[i].ct_name = SPLAT_CONDVAR_TEST3_NAME;
 		ct[i].ct_rc = 0;
-		ct[i].ct_thread = kthread_create(splat_condvar_test34_thread,
+		ct[i].ct_thread = spl_kthread_create(splat_condvar_test34_thread,
 		    &ct[i], "%s/%d", SPLAT_CONDVAR_TEST_NAME, i);
 
 		if (!IS_ERR(ct[i].ct_thread)) {

module/splat/splat-rwlock.c

@@ -215,10 +215,10 @@ splat_rwlock_test1(struct file *file, void *arg)
 
 		/* The first thread will be the writer */
 		if (i == 0)
-			rwt[i].rwt_thread = kthread_create(splat_rwlock_wr_thr,
+			rwt[i].rwt_thread = spl_kthread_create(splat_rwlock_wr_thr,
 			    &rwt[i], "%s/%d", SPLAT_RWLOCK_TEST_NAME, i);
 		else
-			rwt[i].rwt_thread = kthread_create(splat_rwlock_rd_thr,
+			rwt[i].rwt_thread = spl_kthread_create(splat_rwlock_rd_thr,
 			    &rwt[i], "%s/%d", SPLAT_RWLOCK_TEST_NAME, i);
 
 		if (!IS_ERR(rwt[i].rwt_thread)) {