[Intel-gfx] [PATCH i-g-t] lib/dummyload: Handle timeout in a new thread instead of signal handler

[Ander Conselvan de Oliveira]

Currently, the main thread needs to wakeup to run the signal handler
that ends a spin batch. When testing whether a function call succesfully
waits for a batch to complete, this behavior is undesired. It actually
invalidates the test.

Fix this by spawning a new thread to handle the timeout.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
---
 lib/igt_dummyload.c | 55 +++++++++++++++++------------------------------------
 lib/igt_dummyload.h |  3 ++-
 2 files changed, 19 insertions(+), 39 deletions(-)

diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
index 019c1fb..38b1930 100644
--- a/lib/igt_dummyload.c
+++ b/lib/igt_dummyload.c
@@ -24,6 +24,7 @@
 
 #include "igt.h"
 #include "igt_dummyload.h"
+#include <pthread.h>
 #include <time.h>
 #include <signal.h>
 #include <sys/syscall.h>
@@ -166,6 +167,8 @@ igt_spin_batch_new(int fd, int engine, unsigned int dep_handle)
 	spin = calloc(1, sizeof(struct igt_spin));
 	igt_assert(spin);
 
+	pthread_mutex_init(&spin->mutex, NULL);
+
 	emit_recursive_batch(spin, fd, engine, dep_handle);
 	igt_assert(gem_bo_busy(fd, spin->handle));
 
@@ -174,27 +177,11 @@ igt_spin_batch_new(int fd, int engine, unsigned int dep_handle)
 	return spin;
 }
 
-static void clear_sig_handler(int sig)
-{
-	struct sigaction act;
-
-	memset(&act, 0, sizeof(act));
-	act.sa_handler = SIG_DFL;
-	igt_assert(sigaction(sig, &act, NULL) == 0);
-}
-
-static void sig_handler(int sig, siginfo_t *info, void *arg)
+static void notify(union sigval arg)
 {
-	struct igt_spin *iter;
+	igt_spin_t *spin = arg.sival_ptr;
 
-	igt_list_for_each(iter, &spin_list, link) {
-		if (iter->signo == info->si_signo) {
-			igt_spin_batch_end(iter);
-			return;
-		}
-	}
-
-	clear_sig_handler(sig);
+	igt_spin_batch_end(spin);
 }
 
 /**
@@ -208,43 +195,33 @@ static void sig_handler(int sig, siginfo_t *info, void *arg)
  */
 void igt_spin_batch_set_timeout(igt_spin_t *spin, int64_t ns)
 {
-	static int spin_signo = 48; /* Midpoint of SIGRTMIN, SIGRTMAX */
 	timer_t timer;
 	struct sigevent sev;
-	struct sigaction act, oldact;
 	struct itimerspec its;
 
+	pthread_mutex_lock(&spin->mutex);
+
 	igt_assert(ns > 0);
 	if (!spin)
 		return;
 
 	igt_assert(!spin->timer);
 
-	/* SIGRTMAX is used by valgrind, SIGRTMAX - 1 by igt_fork_hang_detector */
-	if (spin_signo >= SIGRTMAX - 2)
-		spin_signo = SIGRTMIN;
-	spin->signo = ++spin_signo;
-
 	memset(&sev, 0, sizeof(sev));
-	sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
-	sev.sigev_notify_thread_id = gettid();
-	sev.sigev_signo = spin->signo;
+	sev.sigev_notify = SIGEV_THREAD;
+	sev.sigev_value.sival_ptr = spin;
+	sev.sigev_notify_function = notify;
 	igt_assert(timer_create(CLOCK_MONOTONIC, &sev, &timer) == 0);
 	igt_assert(timer);
 
-	memset(&oldact, 0, sizeof(oldact));
-	memset(&act, 0, sizeof(act));
-	act.sa_sigaction = sig_handler;
-	act.sa_flags = SA_SIGINFO;
-	igt_assert(sigaction(spin->signo, &act, &oldact) == 0);
-	igt_assert(oldact.sa_sigaction == NULL);
-
 	memset(&its, 0, sizeof(its));
 	its.it_value.tv_sec = ns / NSEC_PER_SEC;
 	its.it_value.tv_nsec = ns % NSEC_PER_SEC;
 	igt_assert(timer_settime(timer, 0, &its, NULL) == 0);
 
 	spin->timer = timer;
+
+	pthread_mutex_unlock(&spin->mutex);
 }
 
 /**
@@ -258,11 +235,12 @@ void igt_spin_batch_end(igt_spin_t *spin)
 	if (!spin)
 		return;
 
+	pthread_mutex_lock(&spin->mutex);
+
 	*spin->batch = MI_BATCH_BUFFER_END;
 	__sync_synchronize();
 
-	if (spin->signo)
-		clear_sig_handler(spin->signo);
+	pthread_mutex_unlock(&spin->mutex);
 }
 
 /**
@@ -287,6 +265,7 @@ void igt_spin_batch_free(int fd, igt_spin_t *spin)
 	gem_munmap(spin->batch, BATCH_SIZE);
 
 	gem_close(fd, spin->handle);
+	pthread_mutex_destroy(&spin->mutex);
 	free(spin);
 }
 
diff --git a/lib/igt_dummyload.h b/lib/igt_dummyload.h
index 2adfadf..8fdc3fe 100644
--- a/lib/igt_dummyload.h
+++ b/lib/igt_dummyload.h
@@ -31,11 +31,12 @@
 #include "igt_aux.h"
 
 typedef struct igt_spin {
+	pthread_mutex_t mutex;
 	unsigned int handle;
 	timer_t timer;
-	int signo;
 	struct igt_list link;
 	uint32_t *batch;
+
 } igt_spin_t;
 
 igt_spin_t *igt_spin_batch_new(int fd, int engine, unsigned int dep_handle);
-- 
2.9.3