From b67d56c7b3b0f84360db749aa6f431a07761d9c8 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Tue, 8 Dec 2020 18:02:39 -0500 Subject: drop use of pthread_once for aio thread stack size init pthread_once is not compatible with MT-fork constraints (commit 167390f05564e0a4d3fcb4329377fd7743267560) and is not needed here anyway; we already have a lock suitable for initialization. while changing this, fix a corner case where AT_MINSIGSTKSZ gives a value that's more than MINSIGSTKSZ but by a margin of less than 2048, thereby causing the size to be reduced. it shouldn't matter but the intent was to be the larger of a 2048-byte margin over the legacy fixed minimum stack requirement or a 512-byte margin over the minimum the kernel reports at runtime. --- src/aio/aio.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/src/aio/aio.c b/src/aio/aio.c index e004f98b..a1a3e791 100644 --- a/src/aio/aio.c +++ b/src/aio/aio.c @@ -76,6 +76,10 @@ static struct aio_queue *****map; static volatile int aio_fd_cnt; volatile int __aio_fut; +static size_t io_thread_stack_size; + +#define MAX(a,b) ((a)>(b) ? (a) : (b)) + static struct aio_queue *__aio_get_queue(int fd, int need) { if (fd < 0) { @@ -90,6 +94,10 @@ static struct aio_queue *__aio_get_queue(int fd, int need) pthread_rwlock_unlock(&maplock); if (fcntl(fd, F_GETFD) < 0) return 0; pthread_rwlock_wrlock(&maplock); + if (!io_thread_stack_size) { + unsigned long val = __getauxval(AT_MINSIGSTKSZ); + io_thread_stack_size = MAX(MINSIGSTKSZ+2048, val+512); + } if (!map) map = calloc(sizeof *map, (-1U/2+1)>>24); if (!map) goto out; if (!map[a]) map[a] = calloc(sizeof **map, 256); @@ -265,15 +273,6 @@ static void *io_thread_func(void *ctx) return 0; } -static size_t io_thread_stack_size = MINSIGSTKSZ+2048; -static pthread_once_t init_stack_size_once; - -static void init_stack_size() -{ - unsigned long val = __getauxval(AT_MINSIGSTKSZ); - if (val > MINSIGSTKSZ) io_thread_stack_size = val + 512; -} - static int submit(struct aiocb *cb, int op) { int ret = 0; @@ -299,7 +298,6 @@ static int submit(struct aiocb *cb, int op) else pthread_attr_init(&a); } else { - pthread_once(&init_stack_size_once, init_stack_size); pthread_attr_init(&a); pthread_attr_setstacksize(&a, io_thread_stack_size); pthread_attr_setguardsize(&a, 0); -- cgit v1.2.1