From 9381a9d8926005ef57a3e8add7fb21e42e01d08c 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 4effecc1cd8..4266d6be214 100644 --- a/tests/sys/fs/fusefs/mockfs.cc +++ b/tests/sys/fs/fusefs/mockfs.cc @@ -823,6 +823,7 @@ 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: @@ -859,19 +860,22 @@ 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 be8a05c344f..39160670437 100644 --- a/tests/sys/fs/fusefs/mockfs.hh +++ b/tests/sys/fs/fusefs/mockfs.hh @@ -264,7 +264,7 @@ 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; -- 2.45.0