From 01b8b847f5fc4b65eaac06c7c2d85f8c5410c497 Mon Sep 17 00:00:00 2001 From: dickmao Date: Sun, 6 Jun 2021 11:10:13 -0400 Subject: [PATCH] Revert "Fix lock failures in xg_select" This reverts commit 9c62ffb08262c82b7e38e6eb5767f2087424aa47. * src/thread.c (really_call_select): revert 9c62ffb * src/xgselect.c (xg_select): revert 9c62ffb --- src/thread.c | 8 -------- src/xgselect.c | 42 ++++++++++++++---------------------------- src/xgselect.h | 2 -- 3 files changed, 14 insertions(+), 38 deletions(-) diff --git a/src/thread.c b/src/thread.c index f74f611148..609cd7c5fc 100644 --- a/src/thread.c +++ b/src/thread.c @@ -28,12 +28,6 @@ Copyright (C) 2012-2021 Free Software Foundation, Inc. #include "pdumper.h" #include "keyboard.h" -#if defined HAVE_GLIB && ! defined (HAVE_NS) -#include -#else -#define release_select_lock() do { } while (0) -#endif - union aligned_thread_state { struct thread_state s; @@ -592,8 +586,6 @@ really_call_select (void *arg) sa->result = (sa->func) (sa->max_fds, sa->rfds, sa->wfds, sa->efds, sa->timeout, sa->sigmask); - release_select_lock (); - block_interrupt_signal (&oldset); /* If we were interrupted by C-g while inside sa->func above, the signal handler could have called maybe_reacquire_global_lock, in diff --git a/src/xgselect.c b/src/xgselect.c index 0d91d55bad..d7c63e3be1 100644 --- a/src/xgselect.c +++ b/src/xgselect.c @@ -29,27 +29,6 @@ Copyright (C) 2009-2021 Free Software Foundation, Inc. #include "blockinput.h" #include "systime.h" -static ptrdiff_t threads_holding_glib_lock; -static GMainContext *glib_main_context; - -void release_select_lock (void) -{ - if (--threads_holding_glib_lock == 0) - g_main_context_release (glib_main_context); -} - -static void acquire_select_lock (GMainContext *context) -{ - if (threads_holding_glib_lock++ == 0) - { - glib_main_context = context; - while (!g_main_context_acquire (context)) - { - /* Spin. */ - } - } -} - /* `xg_select' is a `pselect' replacement. Why do we need a separate function? 1. Timeouts. Glib and Gtk rely on timer events. If we did pselect with a greater timeout then the one scheduled by Glib, we would @@ -75,19 +54,26 @@ xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds, GPollFD *gfds = gfds_buf; int gfds_size = ARRAYELTS (gfds_buf); int n_gfds, retval = 0, our_fds = 0, max_fds = fds_lim - 1; + bool context_acquired = false; int i, nfds, tmo_in_millisec, must_free = 0; bool need_to_dispatch; context = g_main_context_default (); - acquire_select_lock (context); + context_acquired = g_main_context_acquire (context); + /* FIXME: If we couldn't acquire the context, we just silently proceed + because this function handles more than just glib file descriptors. + Note that, as implemented, this failure is completely silent: there is + no feedback to the caller. */ if (rfds) all_rfds = *rfds; else FD_ZERO (&all_rfds); if (wfds) all_wfds = *wfds; else FD_ZERO (&all_wfds); - n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec, - gfds, gfds_size); + n_gfds = (context_acquired + ? g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec, + gfds, gfds_size) + : -1); if (gfds_size < n_gfds) { @@ -165,10 +151,8 @@ xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds, #else need_to_dispatch = true; #endif - if (need_to_dispatch) + if (need_to_dispatch && context_acquired) { - acquire_select_lock (context); - int pselect_errno = errno; /* Prevent g_main_dispatch recursion, that would occur without block_input wrapper, because event handlers call @@ -178,9 +162,11 @@ xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds, g_main_context_dispatch (context); unblock_input (); errno = pselect_errno; - release_select_lock (); } + if (context_acquired) + g_main_context_release (context); + /* To not have to recalculate timeout, return like this. */ if ((our_fds > 0 || (nfds == 0 && tmop == &tmo)) && (retval == 0)) { diff --git a/src/xgselect.h b/src/xgselect.h index 2142a236b2..e00dce1283 100644 --- a/src/xgselect.h +++ b/src/xgselect.h @@ -29,6 +29,4 @@ #define XGSELECT_H fd_set *rfds, fd_set *wfds, fd_set *efds, struct timespec *timeout, sigset_t *sigmask); -extern void release_select_lock (void); - #endif /* XGSELECT_H */ -- 2.26.2