[LTP] [PATCH v4 1/2] poll: add basic POLLHUP semantics test

[Jinseok Kim]

Add a basic poll() test to verify that POLLHUP is reported when the
peer end of a pipe is closed.

The test creates a pipe, closes the write end, and polls the read end
for POLLIN events. poll() is expected to return successfully and set
POLLHUP in revents.

This covers basic poll() lifecycle semantics that were not previously
tested.

Signed-off-by: Jinseok Kim <always.starving0@gmail.com>
---
 runtest/syscalls                          |  1 +
 testcases/kernel/syscalls/poll/.gitignore |  1 +
 testcases/kernel/syscalls/poll/poll03.c   | 61 +++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 testcases/kernel/syscalls/poll/poll03.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 05bb3ceb1..15df7c414 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1092,6 +1092,7 @@ pivot_root01 pivot_root01

 poll01 poll01
 poll02 poll02
+poll03 poll03

 ppoll01 ppoll01

diff --git a/testcases/kernel/syscalls/poll/.gitignore b/testcases/kernel/syscalls/poll/.gitignore
index 83be0ddf8..e3f66f4e6 100644
--- a/testcases/kernel/syscalls/poll/.gitignore
+++ b/testcases/kernel/syscalls/poll/.gitignore
@@ -1,2 +1,3 @@
 /poll01
 /poll02
+/poll03
diff --git a/testcases/kernel/syscalls/poll/poll03.c b/testcases/kernel/syscalls/poll/poll03.c
new file mode 100644
index 000000000..182d8bd3c
--- /dev/null
+++ b/testcases/kernel/syscalls/poll/poll03.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Jinseok Kim <always.starving0@gmail.com>
+ */
+
+/*\
+ * Check that poll() reports POLLHUP on a pipe read end
+ * after the write end has been closed.
+ */
+#include <unistd.h>
+#include <errno.h>
+#include <sys/poll.h>
+
+#include "tst_test.h"
+
+static int fds[2];
+
+static void verify_pollhup(void)
+{
+	struct pollfd pfd = {
+		.fd = fds[0], .events = POLLIN,
+	};
+
+	TEST(poll(&pfd, 1, -1));
+
+	if (TST_RET == -1) {
+		tst_res(TFAIL | TTERRNO, "poll() failed");
+		return;
+	}
+
+	if (TST_RET != 1) {
+		tst_res(TFAIL, "Unexpected poll() return value %ld", TST_RET);
+		return;
+	}
+
+	TST_EXP_EXPR(pfd.revents & POLLHUP);
+	TST_EXP_EXPR((pfd.revents & ~POLLHUP) == 0);
+
+	tst_res(TPASS, "poll() reported POLLHUP");
+}
+
+static void setup(void)
+{
+	SAFE_PIPE(fds);
+	SAFE_CLOSE(fds[1]);
+}
+
+static void cleanup(void)
+{
+	if (fds[0] > 0)
+		SAFE_CLOSE(fds[0]);
+
+	if (fds[1] > 0)
+		SAFE_CLOSE(fds[1]);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = verify_pollhup,
+};
--
2.43.0