[LTP] [PATCH v2] netstress: explicitly set a thread stack size

[j.nixdorf@avm.de <j.nixdorf@avm.de>]

Musl libc uses a relatively small thread stack size (128k [1]). This
gets used up on 2 local buffers sized max_msg_len (64k by default),
which causes a segfault due to a stack overflow in the error reporting
path.

Set the stack size to 256k instead, which is enough for both buffers
with an additional allowance for the remaining stack usage by netstress
and called libc or ltp helper functions.

[1]: https://wiki.musl-libc.org/functional-differences-from-glibc.html#Thread_stack_size

Signed-off-by: Johannes Nixdorf <j.nixdorf@avm.de>

---

v2:
  - Use a static limit of 256k.
  - Document the requested stack size in the error message.
  - Coding style fixup.

 testcases/network/netstress/netstress.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/testcases/network/netstress/netstress.c b/testcases/network/netstress/netstress.c
index e79e64220..48c0c23dc 100644
--- a/testcases/network/netstress/netstress.c
+++ b/testcases/network/netstress/netstress.c
@@ -480,7 +480,7 @@ static void client_init(void)
 	clock_gettime(CLOCK_MONOTONIC_RAW, &tv_client_start);
 	intptr_t i;
 	for (i = 0; i < clients_num; ++i)
-		SAFE_PTHREAD_CREATE(&thread_ids[i], 0, client_fn, (void *)i);
+		SAFE_PTHREAD_CREATE(&thread_ids[i], &attr, client_fn, (void *)i);
 }
 
 static void client_run(void)
@@ -747,8 +747,6 @@ static void server_run(void)
 	struct sockaddr_in6 addr6;
 	socklen_t addr_size = sizeof(addr6);
 
-	pthread_attr_init(&attr);
-
 	/*
 	 * detaching threads allow to reclaim thread's resources
 	 * once a thread finishes its work.
@@ -980,6 +978,12 @@ static void setup(void)
 	break;
 	}
 
+	if (errno = pthread_attr_init(&attr))
+		tst_brk(TBROK | TERRNO, "pthread_attr_init failed");
+
+	if (errno = pthread_attr_setstacksize(&attr, 256*1024))
+		tst_brk(TBROK | TERRNO, "pthread_attr_setstacksize(256*1024) failed");
+
 	net.init();
 }
 
-- 
2.17.1