From 85d028223bc2768651f4d44881644ceb5dc2a664 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Tue, 12 Jan 2021 11:02:37 +0200 Subject: [PATCH] libthr malloc: support recursion on thr_malloc_umtx. One possible way the recursion can happen is during fork: suppose that fork is called from early code that did not triggered jemalloc(3) initialization yet. Then we lock thr_malloc lock, and call malloc_prefork() that might require initialization of jemalloc pthread_mutexes, calling into libthr malloc. It is safe to allow recursion for this occurence. PR: 252579 Reported by: Vasily Postnicov MFC after: 1 week Sponsored by: The FreeBSD Foundation --- lib/libthr/thread/thr_malloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/lib/libthr/thread/thr_malloc.c b/lib/libthr/thread/thr_malloc.c index 2f1c81142942..80a81f9c6c27 100644 --- a/lib/libthr/thread/thr_malloc.c +++ b/lib/libthr/thread/thr_malloc.c @@ -41,6 +41,7 @@ int npagesizes; size_t *pagesizes; static size_t pagesizes_d[2]; static struct umutex thr_malloc_umtx; +static u_int thr_malloc_umtx_level; void __thr_malloc_init(void) @@ -60,11 +61,16 @@ __thr_malloc_init(void) static void thr_malloc_lock(struct pthread *curthread) { + uint32_t curtid; if (curthread == NULL) return; curthread->locklevel++; - _thr_umutex_lock(&thr_malloc_umtx, TID(curthread)); + curtid = TID(curthread); + if ((uint32_t)thr_malloc_umtx.m_owner == curtid) + thr_malloc_umtx_level++; + else + _thr_umutex_lock(&thr_malloc_umtx, curtid); } static void @@ -73,7 +79,10 @@ thr_malloc_unlock(struct pthread *curthread) if (curthread == NULL) return; - _thr_umutex_unlock(&thr_malloc_umtx, TID(curthread)); + if (thr_malloc_umtx_level > 0) + thr_malloc_umtx_level--; + else + _thr_umutex_unlock(&thr_malloc_umtx, TID(curthread)); curthread->locklevel--; _thr_ast(curthread); }