https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a22a0ad7c4f0350a6b144be7718611630c33c503
commit a22a0ad7c4f0350a6b144be7718611630c33c503 Author: Takashi Yano <[email protected]> Date: Mon Dec 23 03:23:37 2024 +0900 Cygwin: signal: Do not handle signal when __SIGFLUSHFAST is sent After the commit d243e51ef1d3, zsh sometimes hangs at startup. This occurs because SIGCHLD, which should trigger sigsuspend(), is handled in cygwait() that is used to wait for a wakeup event in sig_send(), even when __SIGFLUSHFAST is sent. Despite __SIGFLUSHFAST being required to return before handling the signal, this does not happen. With this patch, if the signal currently being sent is __SIGFLUSHFAST, do not handle the received signal and keep it asserted after the cygwait() for the wakeup event. Apply the same logic to the cygwait() in the retrying loop for WriteFile() as well. Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256954.html Fixes: d243e51ef1d3 ("Cygwin: signal: Fix deadlock between main thread and sig thread") Reported-by: Daisuke Fujimura <[email protected]> Reviewed-by: Corinna Vinschen <[email protected]> Signed-off-by: Takashi Yano <[email protected]> Diff: --- winsup/cygwin/release/3.5.6 | 3 +++ winsup/cygwin/sigproc.cc | 20 +++++++++++++++----- 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/winsup/cygwin/release/3.5.6 b/winsup/cygwin/release/3.5.6 index d17a6af53..0fff0de40 100644 --- a/winsup/cygwin/release/3.5.6 +++ b/winsup/cygwin/release/3.5.6 @@ -7,3 +7,6 @@ Fixes: - Fix a regression since 3.5.0 which fails to use POSIX semantics in unlink/rename on NTFS. + +- Fix zsh hang at startup. + Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256954.html diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc index ba7818a68..35ec3e70e 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -751,10 +751,14 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls) res = WriteFile (sendsig, leader, packsize, &nb, NULL); if (!res || packsize == nb) break; - if (cygwait (NULL, 10, cw_sig_eintr) == WAIT_SIGNALED) + if (cygwait (NULL, 10, cw_sig_eintr) == WAIT_SIGNALED + && pack.si.si_signo != __SIGFLUSHFAST) _my_tls.call_signal_handler (); res = 0; } + /* Re-assert signal_arrived which has been cleared in cygwait(). */ + if (_my_tls.current_sig) + _my_tls.set_signal_arrived (); if (!res) { @@ -785,7 +789,16 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls) if (wait_for_completion) { sigproc_printf ("Waiting for pack.wakeup %p", pack.wakeup); - rc = cygwait (pack.wakeup, WSSC); + do + { + rc = cygwait (pack.wakeup, WSSC, cw_sig_eintr); + if (rc == WAIT_SIGNALED && pack.si.si_signo != __SIGFLUSHFAST) + _my_tls.call_signal_handler (); + } + while (rc != WAIT_OBJECT_0 && rc != WAIT_TIMEOUT); + /* Re-assert signal_arrived which has been cleared in cygwait(). */ + if (_my_tls.current_sig) + _my_tls.set_signal_arrived (); ForceCloseHandle (pack.wakeup); } else @@ -806,9 +819,6 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls) rc = -1; } - if (wait_for_completion && si.si_signo != __SIGFLUSHFAST) - _my_tls.call_signal_handler (); - out: if (communing && rc) {
