From 0a44675ba50a9e440ded268bb2a728c044a4f20c Mon Sep 17 00:00:00 2001 From: Alan Somers Date: Sat, 25 Sep 2021 10:16:20 -0600 Subject: [PATCH] fusefs: fix intermittency in the dev_fuse_poll test The DevFusePoll::access/select test would occasionally segfault. The cause was a file descriptor that was shared between two threads. The first thread would kill the second and close the file descriptor. But it was possible that the second would read the file descriptor before it shut down. That did not cause problems for kqueue, poll, or blocking operation, but it triggered segfaults in select's macros. Differential Revision: https://reviews.freebsd.org/D32142 (cherry picked from commit f44a448709d3b77508fd59ee28201ae1666387c2) --- tests/sys/fs/fusefs/mockfs.cc | 10 +++++++--- tests/sys/fs/fusefs/mockfs.hh | 2 +- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc index 4d0724b9c22..99f7ccc6127 100644 --- a/tests/sys/fs/fusefs/mockfs.cc +++ b/tests/sys/fs/fusefs/mockfs.cc @@ -870,6 +870,7 @@ void MockFS::read_request(mockfs_buf_in &in, ssize_t &res) { struct timeval timeout_tv; const int timeout_ms = 999; int timeout_int, nfds; + int fuse_fd; switch (m_pm) { case BLOCKING: @@ -906,19 +907,22 @@ void MockFS::read_request(mockfs_buf_in &in, ssize_t &res) { ASSERT_TRUE(fds[0].revents & POLLIN); break; case SELECT: + fuse_fd = m_fuse_fd; + if (fuse_fd < 0) + break; timeout_tv.tv_sec = 0; timeout_tv.tv_usec = timeout_ms * 1'000; - nfds = m_fuse_fd + 1; + nfds = fuse_fd + 1; while (nready == 0) { FD_ZERO(&readfds); - FD_SET(m_fuse_fd, &readfds); + FD_SET(fuse_fd, &readfds); nready = select(nfds, &readfds, NULL, NULL, &timeout_tv); if (m_quit) return; } ASSERT_LE(0, nready) << strerror(errno); - ASSERT_TRUE(FD_ISSET(m_fuse_fd, &readfds)); + ASSERT_TRUE(FD_ISSET(fuse_fd, &readfds)); break; default: FAIL() << "not yet implemented"; diff --git a/tests/sys/fs/fusefs/mockfs.hh b/tests/sys/fs/fusefs/mockfs.hh index 24ca017dcdb..600a4b4292c 100644 --- a/tests/sys/fs/fusefs/mockfs.hh +++ b/tests/sys/fs/fusefs/mockfs.hh @@ -284,7 +284,7 @@ class MockFS { pthread_t m_daemon_id; /* file descriptor of /dev/fuse control device */ - int m_fuse_fd; + volatile int m_fuse_fd; /* The minor version of the kernel API that this mock daemon targets */ uint32_t m_kernel_minor_version;