diff --git a/msys2-runtime/0054-cygthread-suspend-thread-before-terminating.patch b/msys2-runtime/0054-cygthread-suspend-thread-before-terminating.patch new file mode 100644 index 00000000000..33291ca18d8 --- /dev/null +++ b/msys2-runtime/0054-cygthread-suspend-thread-before-terminating.patch @@ -0,0 +1,75 @@ +From 6469fc6ad6b20f6a1e7e84e1a4924f4bd77bf48d Mon Sep 17 00:00:00 2001 +From: Johannes Schindelin +Date: Tue, 12 Nov 2024 22:21:08 +0100 +Subject: [PATCH 54/N] cygthread: suspend thread before terminating. + +This addresses an extremely difficult to debug deadlock when running +under emulation on ARM64. + +A relatively easy way to trigger this bug is to call `fork()`, then +within the child process immediately call another `fork()` and then +`exit()` the intermediate process. + +It would seem that there is a "code emulation" lock on the wait thread +at this stage, and if the thread is terminated too early, that lock +still exists albeit without a thread, and nothing moves forward. + +It seems that a `SuspendThread()` combined with a `GetThreadContext()` +(to force the thread to _actually_ be suspended, for more details see +https://devblogs.microsoft.com/oldnewthing/20150205-00/?p=44743) makes +sure the thread is "booted" from emulation before it is suspended. + +Hopefully this means it won't be holding any locks or otherwise leave +emulation in a bad state when the thread is terminated. + +Also, attempt to use `CancelSynchonousIo()` (as seen in `flock.cc`) to +avoid the need for `TerminateThread()` altogether. This doesn't always +work, however, so was not a complete fix for the deadlock issue. + +Addresses: https://cygwin.com/pipermail/cygwin-developers/2024-May/012694.html +Signed-off-by: Jeremy Drake +Signed-off-by: Johannes Schindelin +--- + winsup/cygwin/cygthread.cc | 14 ++++++++++++++ + winsup/cygwin/sigproc.cc | 3 ++- + 2 files changed, 16 insertions(+), 1 deletion(-) + +diff --git a/winsup/cygwin/cygthread.cc b/winsup/cygwin/cygthread.cc +index 54918e7..4f16097 100644 +--- a/winsup/cygwin/cygthread.cc ++++ b/winsup/cygwin/cygthread.cc +@@ -302,6 +302,20 @@ cygthread::terminate_thread () + if (!inuse) + goto force_notterminated; + ++ if (_my_tls._ctinfo != this) ++ { ++ CONTEXT context; ++ context.ContextFlags = CONTEXT_CONTROL; ++ /* SuspendThread makes sure a thread is "booted" from emulation before ++ it is suspended. As such, the emulator hopefully won't be in a bad ++ state (aka, holding any locks) when the thread is terminated. */ ++ SuspendThread (h); ++ /* We need to call GetThreadContext, even though we don't care about the ++ context, because SuspendThread is asynchronous and GetThreadContext ++ will make sure the thread is *really* suspended before returning */ ++ GetThreadContext (h, &context); ++ } ++ + TerminateThread (h, 0); + WaitForSingleObject (h, INFINITE); + CloseHandle (h); +diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc +index 5c5ff73..d180277 100644 +--- a/winsup/cygwin/sigproc.cc ++++ b/winsup/cygwin/sigproc.cc +@@ -410,7 +410,8 @@ proc_terminate () + if (!have_execed || !have_execed_cygwin) + chld_procs[i]->ppid = 1; + if (chld_procs[i].wait_thread) +- chld_procs[i].wait_thread->terminate_thread (); ++ if (!CancelSynchronousIo (chld_procs[i].wait_thread->thread_handle ())) ++ chld_procs[i].wait_thread->terminate_thread (); + /* Release memory associated with this process unless it is 'myself'. + 'myself' is only in the chld_procs table when we've execed. We + reach here when the next process has finished initializing but we diff --git a/msys2-runtime/PKGBUILD b/msys2-runtime/PKGBUILD index 118c5399bcc..2d9c747ce72 100644 --- a/msys2-runtime/PKGBUILD +++ b/msys2-runtime/PKGBUILD @@ -4,7 +4,7 @@ pkgbase=msys2-runtime pkgname=('msys2-runtime' 'msys2-runtime-devel') pkgver=3.5.4 -pkgrel=3 +pkgrel=4 pkgdesc="Cygwin POSIX emulation engine" arch=('x86_64') url="https://www.cygwin.com/" @@ -79,9 +79,10 @@ source=('msys2-runtime'::git+https://github.com/cygwin/cygwin#tag=cygwin-${pkgve 0050-Cygwin-pipe-Fix-a-regression-that-raw_write-slows-do.patch 0051-Cygwin-pipe-Restore-blocking-mode-of-read-pipe-on-cl.patch 0052-Fix-SSH-hangs.patch - 0053-Cygwin-find_fast_cwd-don-t-run-assembler-checking-co.patch) + 0053-Cygwin-find_fast_cwd-don-t-run-assembler-checking-co.patch + 0054-cygthread-suspend-thread-before-terminating.patch) sha256sums=('3812485e2a6ab8360e5b9d566a47b982852ff2b140cea4e332ded19c11c77663' - '490f290676fc38e51b5084ed7061c1abb70a462bf3067941b01a52e60662aecc' + 'a1ccf0cab1544eb266caa467817c2d525fe48bc47247c4302b81f46aaada9677' '9f9e1b6b05cbc9a715fe9443740b25171e9c1a276a058e6ba7e4f6eada6872c8' 'e5b2095e543a5d702cfce6da26cd17a78f40e17620315b1bcc434b94a007ae9b' 'f13b15dc14aa6ee1dd628a2487564bb484e74ff2f3e4059b9d9d64446a327db1' @@ -134,7 +135,8 @@ sha256sums=('3812485e2a6ab8360e5b9d566a47b982852ff2b140cea4e332ded19c11c77663' '394229cfa5293e4572dfd7155605343ca7426395429fa47eb38aced11d4f924b' '590dc0ce9e72a1adf1424c7a4f55bd57d8955eef036776895b3d779d4932d4ce' '75e22e453011ea15c6cf6b6904c33256530d6f4ba273f03bc6a37d9245064c8c' - '7fe562197a1f3b67b1e794808186c10ff0186b0fcf8d09a8021499b952d04d2c') + '7fe562197a1f3b67b1e794808186c10ff0186b0fcf8d09a8021499b952d04d2c' + '5ee3136a522cff35da3dd7cf7280f87bc855083832cc5cc3a5d24ea996c9d04c') # Helper macros to help make tasks easier # apply_patch_with_msg() { @@ -241,7 +243,8 @@ prepare() { 0050-Cygwin-pipe-Fix-a-regression-that-raw_write-slows-do.patch \ 0051-Cygwin-pipe-Restore-blocking-mode-of-read-pipe-on-cl.patch \ 0052-Fix-SSH-hangs.patch \ - 0053-Cygwin-find_fast_cwd-don-t-run-assembler-checking-co.patch + 0053-Cygwin-find_fast_cwd-don-t-run-assembler-checking-co.patch \ + 0054-cygthread-suspend-thread-before-terminating.patch } build() { diff --git a/msys2-runtime/msys2-runtime.commit b/msys2-runtime/msys2-runtime.commit index 8cca6b1470d..1ec1c57b7f1 100644 --- a/msys2-runtime/msys2-runtime.commit +++ b/msys2-runtime/msys2-runtime.commit @@ -1 +1 @@ -6183b8336e29b058b63dcf97ff8214b0355f165a +6469fc6ad6b20f6a1e7e84e1a4924f4bd77bf48d