Submitted by: Xi Ruoyao Date: 2025-11-19 Initial Package Version: 8.2.10 Upstream Status: Not applicable: the correct fix is https://github.com/bdwgc/bdwgc/pull/790 but the 8.2.10 release is too different from the development branch to get it backported. The upstream suggests to use this as a temporary (until the next minor release) workaround. Arch and AOSC OS have already shipped this workaround. Origin: https://github.com/AOSC-Dev/aosc-os-abbs/tree/08b4b12f2582/runtime-common/gc/autobuild/patches Description: Revert two commits triggering a crash of applications using GC and libraries forking subprocesses (for example glycin) at the same time. Inkscape is such an application in the book. From 57b81b139e25b25159addbf14dcb78e7df7be781 Mon Sep 17 00:00:00 2001 From: Mingcong Bai Date: Sun, 16 Nov 2025 12:51:43 +0800 Subject: [PATCH 2/3] AOSCOS: Revert "Fix pthread id stored in key thread_specific_data of child process" This reverts commit 2cd0f5e56718a053341d1b5e7df7a3cab9a5ceaa. Link: https://github.com/bdwgc/bdwgc/issues/783#issuecomment-3433334711 Signed-off-by: Mingcong Bai --- include/private/gc_priv.h | 11 ----------- include/private/specific.h | 7 ------- pthread_support.c | 31 +++++++++++++++---------------- specific.c | 27 --------------------------- 4 files changed, 15 insertions(+), 61 deletions(-) diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h index 5e14fd72..90c7f997 100644 --- a/include/private/gc_priv.h +++ b/include/private/gc_priv.h @@ -832,10 +832,6 @@ EXTERN_C_END #include -#if defined(CAN_HANDLE_FORK) && defined(GC_PTHREADS) -# include /* for pthread_t */ -#endif - #if __STDC_VERSION__ >= 201112L # include /* for static_assert */ #endif @@ -1556,13 +1552,6 @@ struct _GC_arrays { # endif size_t _ed_size; /* Current size of above arrays. */ size_t _avail_descr; /* Next available slot. */ - -# if defined(CAN_HANDLE_FORK) && defined(GC_PTHREADS) - /* Value of pthread_self() of the thread which called fork(). */ -# define GC_parent_pthread_self GC_arrays._parent_pthread_self - pthread_t _parent_pthread_self; -# endif - typed_ext_descr_t *_ext_descriptors; /* Points to array of extended */ /* descriptors. */ GC_mark_proc _mark_procs[MAX_MARK_PROCS]; diff --git a/include/private/specific.h b/include/private/specific.h index 029fc7f3..3ed75647 100644 --- a/include/private/specific.h +++ b/include/private/specific.h @@ -109,13 +109,6 @@ GC_INNER int GC_setspecific(tsd * key, void * value); GC_remove_specific_after_fork(key, pthread_self()) GC_INNER void GC_remove_specific_after_fork(tsd * key, pthread_t t); -#ifdef CAN_HANDLE_FORK - /* Update thread-specific data for the survived thread of the child */ - /* process. Should be called once after removing thread-specific data */ - /* for other threads. */ - GC_INNER void GC_update_specific_after_fork(tsd *key); -#endif - /* An internal version of getspecific that assumes a cache miss. */ GC_INNER void * GC_slow_getspecific(tsd * key, word qtid, tse * volatile * cache_entry); diff --git a/pthread_support.c b/pthread_support.c index 937846c7..3a4b22b1 100644 --- a/pthread_support.c +++ b/pthread_support.c @@ -829,6 +829,9 @@ GC_API void GC_CALL GC_register_altstack(void *stack, GC_word stack_size, GC_threads[hv] = me; } +/* Value of pthread_self() of the thread which called fork(). */ +STATIC pthread_t GC_parent_pthread_self; + /* Remove all entries from the GC_threads table, except the one for */ /* the current thread. Also update thread identifiers stored in */ /* the table for the current thread. We need to do this in the */ @@ -892,22 +895,18 @@ STATIC void GC_remove_all_threads_but_me(void) /* Put "me" back to GC_threads. */ store_to_threads_table(THREAD_TABLE_INDEX(me -> id), me); -# ifdef THREAD_LOCAL_ALLOC -# ifdef USE_CUSTOM_SPECIFIC - GC_update_specific_after_fork(GC_thread_key); -# else - { - int res; - - /* Some TLS implementations might be not fork-friendly, so */ - /* we re-assign thread-local pointer to 'tlfs' for safety */ - /* instead of the assertion check (again, it is OK to call */ - /* GC_destroy_thread_local and GC_free_inner before). */ - res = GC_setspecific(GC_thread_key, &me->tlfs); - if (COVERT_DATAFLOW(res) != 0) - ABORT("GC_setspecific failed (in child)"); - } -# endif +# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_CUSTOM_SPECIFIC) + { + int res; + + /* Some TLS implementations might be not fork-friendly, so */ + /* we re-assign thread-local pointer to 'tlfs' for safety */ + /* instead of the assertion check (again, it is OK to call */ + /* GC_destroy_thread_local and GC_free_inner before). */ + res = GC_setspecific(GC_thread_key, &me->tlfs); + if (COVERT_DATAFLOW(res) != 0) + ABORT("GC_setspecific failed (in child)"); + } # endif } #endif /* CAN_HANDLE_FORK */ diff --git a/specific.c b/specific.c index 1293d40b..09387ac3 100644 --- a/specific.c +++ b/specific.c @@ -133,33 +133,6 @@ GC_INNER void GC_remove_specific_after_fork(tsd * key, pthread_t t) ABORT("pthread_mutex_unlock failed (remove_specific after fork)"); } -#ifdef CAN_HANDLE_FORK - GC_INNER void - GC_update_specific_after_fork(tsd *key) - { - unsigned hash_val = HASH(GC_parent_pthread_self); - tse *entry; - - GC_ASSERT(I_HOLD_LOCK()); -# ifdef LINT2 - pthread_mutex_lock(&key->lock); -# endif - entry = key->hash[hash_val].p; - if (EXPECT(entry != NULL, TRUE)) { - GC_ASSERT(THREAD_EQUAL(entry->thread, GC_parent_pthread_self)); - GC_ASSERT(NULL == entry->next); - /* Remove the entry from the table. */ - key->hash[hash_val].p = NULL; - entry->thread = pthread_self(); - /* Then put the entry back to the table (based on new hash value). */ - key->hash[HASH(entry->thread)].p = entry; - } -# ifdef LINT2 - (void)pthread_mutex_unlock(&key->lock); -# endif - } -#endif - /* Note that even the slow path doesn't lock. */ GC_INNER void * GC_slow_getspecific(tsd * key, word qtid, tse * volatile * cache_ptr) -- 2.51.1 From f2ec374b22ef3e1631fc87d5dd9fb6ef10acb5e4 Mon Sep 17 00:00:00 2001 From: Mingcong Bai Date: Sun, 16 Nov 2025 12:51:53 +0800 Subject: [PATCH 3/3] AOSCOS: Revert "Fix pthread id stored in GC_threads of child process" This reverts commit 74fc05d128c4ad9860740d73b4c7fd43ea18e74a. Link: https://github.com/bdwgc/bdwgc/issues/783#issuecomment-3433334711 Signed-off-by: Mingcong Bai --- pthread_support.c | 84 +++++++++++++++++------------------------------ 1 file changed, 30 insertions(+), 54 deletions(-) diff --git a/pthread_support.c b/pthread_support.c index 3a4b22b1..3d85bc59 100644 --- a/pthread_support.c +++ b/pthread_support.c @@ -829,28 +829,47 @@ GC_API void GC_CALL GC_register_altstack(void *stack, GC_word stack_size, GC_threads[hv] = me; } -/* Value of pthread_self() of the thread which called fork(). */ -STATIC pthread_t GC_parent_pthread_self; - -/* Remove all entries from the GC_threads table, except the one for */ -/* the current thread. Also update thread identifiers stored in */ -/* the table for the current thread. We need to do this in the */ -/* child process after a fork(), since only the current thread */ -/* survives in the child. */ +/* Remove all entries from the GC_threads table, except the */ +/* one for the current thread. We need to do this in the child */ +/* process after a fork(), since only the current thread */ +/* survives in the child. */ STATIC void GC_remove_all_threads_but_me(void) { + pthread_t self = pthread_self(); int hv; - GC_thread me = NULL; for (hv = 0; hv < THREAD_TABLE_SZ; ++hv) { GC_thread p, next; + GC_thread me = NULL; for (p = GC_threads[hv]; 0 != p; p = next) { next = p -> next; - if (THREAD_EQUAL(p -> id, GC_parent_pthread_self) + if (THREAD_EQUAL(p -> id, self) && me == NULL) { /* ignore dead threads with the same id */ me = p; p -> next = 0; +# ifdef GC_DARWIN_THREADS + /* Update thread Id after fork (it is OK to call */ + /* GC_destroy_thread_local and GC_free_inner */ + /* before update). */ + me -> stop_info.mach_thread = mach_thread_self(); +# endif +# ifdef USE_TKILL_ON_ANDROID + me -> kernel_id = gettid(); +# endif +# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_CUSTOM_SPECIFIC) + { + int res; + + /* Some TLS implementations might be not fork-friendly, so */ + /* we re-assign thread-local pointer to 'tlfs' for safety */ + /* instead of the assertion check (again, it is OK to call */ + /* GC_destroy_thread_local and GC_free_inner before). */ + res = GC_setspecific(GC_thread_key, &me->tlfs); + if (COVERT_DATAFLOW(res) != 0) + ABORT("GC_setspecific failed (in child)"); + } +# endif } else { # ifdef THREAD_LOCAL_ALLOC if (!(p -> flags & FINISHED)) { @@ -870,44 +889,8 @@ STATIC void GC_remove_all_threads_but_me(void) # endif } } - store_to_threads_table(hv, NULL); - } - -# if defined(CPPCHECK) || defined(LINT2) - if (NULL == me) - ABORT("Current thread is not found after fork"); -# else - GC_ASSERT(me != NULL); -# endif - /* Update pthread's id as it is not guaranteed to be the same */ - /* between this (child) process and the parent one. */ - me -> id = pthread_self(); -# ifdef GC_DARWIN_THREADS - /* Update thread Id after fork (it is OK to call */ - /* GC_destroy_thread_local and GC_free_inner */ - /* before update). */ - me -> stop_info.mach_thread = mach_thread_self(); -# endif -# ifdef USE_TKILL_ON_ANDROID - me -> kernel_id = gettid(); -# endif - - /* Put "me" back to GC_threads. */ - store_to_threads_table(THREAD_TABLE_INDEX(me -> id), me); - -# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_CUSTOM_SPECIFIC) - { - int res; - - /* Some TLS implementations might be not fork-friendly, so */ - /* we re-assign thread-local pointer to 'tlfs' for safety */ - /* instead of the assertion check (again, it is OK to call */ - /* GC_destroy_thread_local and GC_free_inner before). */ - res = GC_setspecific(GC_thread_key, &me->tlfs); - if (COVERT_DATAFLOW(res) != 0) - ABORT("GC_setspecific failed (in child)"); + store_to_threads_table(hv, me); } -# endif } #endif /* CAN_HANDLE_FORK */ @@ -1214,7 +1197,6 @@ static void fork_prepare_proc(void) /* the (one remaining thread in) the child. */ LOCK(); DISABLE_CANCEL(fork_cancel_state); - GC_parent_pthread_self = pthread_self(); /* Following waits may include cancellation points. */ # if defined(PARALLEL_MARK) if (GC_parallel) @@ -1255,9 +1237,6 @@ static void fork_parent_proc(void) } # endif RESTORE_CANCEL(fork_cancel_state); -# ifdef GC_ASSERTIONS - BZERO(&GC_parent_pthread_self, sizeof(pthread_t)); -# endif UNLOCK(); } @@ -1305,9 +1284,6 @@ static void fork_child_proc(void) /* Clean up the thread table, so that just our thread is left. */ GC_remove_all_threads_but_me(); RESTORE_CANCEL(fork_cancel_state); -# ifdef GC_ASSERTIONS - BZERO(&GC_parent_pthread_self, sizeof(pthread_t)); -# endif UNLOCK(); /* Even though after a fork the child only inherits the single */ /* thread that called the fork(), if another thread in the parent */ -- 2.51.1