From 48ff7df9daea86c82a572b0a840bb8371b6b1a29 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Mon, 25 Jan 2021 13:23:48 -0600 Subject: [PATCH] fio: fix dlopen refcounting of dynamic engines ioengine_load() will dlclose the dynamic library if it matches one that we've already got open, but this defeats the built-in refcounting done by dlopen/dlclose. As each thread exits, it calls free_ioengine(), and this may do a final dlclose on a dynamic ioengine that is still in use if we don't have the proper reference count. Fix this by dropping the explicit dlclose of a "matching" dlopened dynamic engine library, and let each dlclose decrement the refcount on the engine library as is normal. This also adds/modifies a couple of debug messages to help track this. Signed-off-by: Eric Sandeen Signed-off-by: Jens Axboe --- init.c | 5 +---- ioengines.c | 8 ++++++-- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/init.c b/init.c index ab38b334..d6dbaf7c 100644 --- a/init.c +++ b/init.c @@ -1109,11 +1109,8 @@ int ioengine_load(struct thread_data *td) if (!ops) goto fail; - if (ops == td->io_ops && dlhandle == td->io_ops->dlhandle) { - if (dlhandle) - dlclose(dlhandle); + if (ops == td->io_ops && dlhandle == td->io_ops->dlhandle) return 0; - } if (dlhandle && dlhandle != td->io_ops->dlhandle) dlclose(dlhandle); diff --git a/ioengines.c b/ioengines.c index dcc9496d..f88b0537 100644 --- a/ioengines.c +++ b/ioengines.c @@ -95,6 +95,7 @@ static void *dlopen_external(struct thread_data *td, const char *engine) sprintf(engine_path, "%s/fio-%s.so", FIO_EXT_ENG_DIR, engine); + dprint(FD_IO, "dlopen external %s\n", engine_path); dlhandle = dlopen(engine_path, RTLD_LAZY); if (!dlhandle) log_info("Engine %s not found; Either name is invalid, was not built, or fio-engine-%s package is missing.\n", @@ -116,7 +117,7 @@ static struct ioengine_ops *dlopen_ioengine(struct thread_data *td, !strncmp(engine_lib, "aio", 3)) engine_lib = "libaio"; - dprint(FD_IO, "dload engine %s\n", engine_lib); + dprint(FD_IO, "dlopen engine %s\n", engine_lib); dlerror(); dlhandle = dlopen(engine_lib, RTLD_LAZY); @@ -194,7 +195,9 @@ struct ioengine_ops *load_ioengine(struct thread_data *td) * so as not to break job files not using the prefix. */ ops = __load_ioengine(td->o.ioengine); - if (!ops) + + /* We do re-dlopen existing handles, for reference counting */ + if (!ops || ops->dlhandle) ops = dlopen_ioengine(td, name); /* @@ -229,6 +232,7 @@ void free_ioengine(struct thread_data *td) } if (td->io_ops->dlhandle) { + dprint(FD_IO, "dlclose ioengine %s\n", td->io_ops->name); dlclose(td->io_ops->dlhandle); td->io_ops->dlhandle = NULL; } -- 2.26.2