The patch titled
Subject: kselftest: introduce new epoll test case
has been added to the -mm tree. Its filename is
kselftest-introduce-new-epoll-test-case.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kselftest-introduce-new-epoll-test-case.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kselftest-introduce-new-epoll-test-case.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: kselftest: introduce new epoll test case
Patch series "fs/epoll: restore user-visible behavior upon event ready".
This series tries to address a change in user visible behavior, reported
in https://bugzilla.kernel.org/show_bug.cgi?id=208943.
Epoll does not report an event to all the threads running epoll_wait()
on the same epoll descriptor. Unsurprisingly, this was bisected back to
339ddb53d373 (fs/epoll: remove unnecessary wakeups of nested epoll), which
has had various problems in the past, beyond only nested epoll usage.
This patch (of 2):
This incorporates the testcase originally reported in:
https://bugzilla.kernel.org/show_bug.cgi?id=208943
Which ensures an event is reported to all threads blocked on the same
epoll descriptor, otherwise only a single thread will receive the wakeup
once the event become ready.
Link: https://lkml.kernel.org/r/20210405231025.33829-1-dave@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20210405231025.33829-2-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Roman Penyaev <rpenyaev@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c | 44 ++++++++++
1 file changed, 44 insertions(+)
--- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c~kselftest-introduce-new-epoll-test-case
+++ a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
@@ -3449,4 +3449,48 @@ TEST(epoll63)
close(sfd[1]);
}
+/*
+ * t0 t1
+ * (ew) \ / (ew)
+ * e0
+ * | (lt)
+ * s0
+ */
+TEST(epoll64)
+{
+ pthread_t waiter[2];
+ struct epoll_event e;
+ struct epoll_mtcontext ctx = { 0 };
+
+ signal(SIGUSR1, signal_handler);
+
+ ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+ ctx.efd[0] = epoll_create(1);
+ ASSERT_GE(ctx.efd[0], 0);
+
+ e.events = EPOLLIN;
+ ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+ /*
+ * main will act as the emitter once both waiter threads are
+ * blocked and expects to both be awoken upon the ready event.
+ */
+ ctx.main = pthread_self();
+ ASSERT_EQ(pthread_create(&waiter[0], NULL, waiter_entry1a, &ctx), 0);
+ ASSERT_EQ(pthread_create(&waiter[1], NULL, waiter_entry1a, &ctx), 0);
+
+ usleep(100000);
+ ASSERT_EQ(write(ctx.sfd[1], "w", 1), 1);
+
+ ASSERT_EQ(pthread_join(waiter[0], NULL), 0);
+ ASSERT_EQ(pthread_join(waiter[1], NULL), 0);
+
+ EXPECT_EQ(ctx.count, 2);
+
+ close(ctx.efd[0]);
+ close(ctx.sfd[0]);
+ close(ctx.sfd[1]);
+}
+
TEST_HARNESS_MAIN
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
kselftest-introduce-new-epoll-test-case.patch
fs-epoll-restore-waking-from-ep_done_scan.patch
