jasonmolenda created this revision.
jasonmolenda added a reviewer: davide.
jasonmolenda added a project: LLDB.
Herald added subscribers: llvm-commits, JDevlieghere.
I hit this while trying to debug lldb-server. When lldb-server is waiting for
connections, it will be in MainLoop::RunImpl::Poll(), in the kevent() call. On
darwin systems, attaching to the process (or interrupting it to add a
breakpoint or detach) will interrupt the system call it is sitting in. We will
get back an error return value (-1) and errno will be set to EINTR.
Currently we flag this as an error and lldb-server exits with
error: IO object is not valid.
which makes it a bit difficult to debug.
This section of code is only used on the *BSD systems and Darwin (it's
#ifdef'ed HAVE_SYS_EVENT_H). I tested it on Darwin and on Linux (before
noticing that linux doesn't have sys/event.h) but don't have access to a *BSD
system. I don't expect any problems handling the interrupted kevent() call on
those systems as I'm doing here.
Repository:
rLLD LLVM Linker
https://reviews.llvm.org/D42206
Files:
source/Host/common/MainLoop.cpp
Index: source/Host/common/MainLoop.cpp
===================================================================
--- source/Host/common/MainLoop.cpp
+++ source/Host/common/MainLoop.cpp
@@ -105,8 +105,11 @@
for (auto &fd : loop.m_read_fds)
EV_SET(&in_events[i++], fd.first, EVFILT_READ, EV_ADD, 0, 0, 0);
- num_events = kevent(loop.m_kqueue, in_events.data(), in_events.size(),
- out_events, llvm::array_lengthof(out_events), nullptr);
+ do {
+ errno = 0;
+ num_events = kevent(loop.m_kqueue, in_events.data(), in_events.size(),
+ out_events, llvm::array_lengthof(out_events), nullptr);
+ } while (num_events == -1 && errno == EINTR);
if (num_events < 0)
return Status("kevent() failed with error %d\n", num_events);
Index: source/Host/common/MainLoop.cpp
===================================================================
--- source/Host/common/MainLoop.cpp
+++ source/Host/common/MainLoop.cpp
@@ -105,8 +105,11 @@
for (auto &fd : loop.m_read_fds)
EV_SET(&in_events[i++], fd.first, EVFILT_READ, EV_ADD, 0, 0, 0);
- num_events = kevent(loop.m_kqueue, in_events.data(), in_events.size(),
- out_events, llvm::array_lengthof(out_events), nullptr);
+ do {
+ errno = 0;
+ num_events = kevent(loop.m_kqueue, in_events.data(), in_events.size(),
+ out_events, llvm::array_lengthof(out_events), nullptr);
+ } while (num_events == -1 && errno == EINTR);
if (num_events < 0)
return Status("kevent() failed with error %d\n", num_events);
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