From 5ea6f1c32628887c9df0c53bc8c199eb12633fec Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Thu, 26 Feb 2015 11:54:03 +0100 Subject: [PATCH] nouveau: make nouveau importing global buffers completely thread-safe, with tests While I've closed off most races in a previous patch, a small race still existed where importing then unreffing cound cause an invalid bo. Add a test for this case. Racing sequence fixed: - thread 1 releases bo, refcount drops to zero, blocks on acquiring nvdev->lock. - thread 2 increases refcount to 1. - thread 2 decreases refcount to zero, blocks on acquiring nvdev->lock. At this point the 2 threads will clean up the same bo. Signed-off-by: Maarten Lankhorst Reviewed-By: Emil Velikov --- configure.ac | 1 + nouveau/nouveau.c | 69 ++++++++++---------- tests/Makefile.am | 4 ++ tests/nouveau/.gitignore | 1 + tests/nouveau/Makefile.am | 16 +++++ tests/nouveau/threaded.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 210 insertions(+), 37 deletions(-) create mode 100644 tests/nouveau/.gitignore create mode 100644 tests/nouveau/Makefile.am create mode 100644 tests/nouveau/threaded.c diff --git a/configure.ac b/configure.ac index 437f4da..106d970 100644 --- a/configure.ac +++ b/configure.ac @@ -454,6 +454,7 @@ AC_CONFIG_FILES([ tests/vbltest/Makefile tests/exynos/Makefile tests/tegra/Makefile + tests/nouveau/Makefile man/Makefile libdrm.pc]) AC_OUTPUT diff --git a/nouveau/nouveau.c b/nouveau/nouveau.c index c6c153a..1c723b9 100644 --- a/nouveau/nouveau.c +++ b/nouveau/nouveau.c @@ -351,29 +351,18 @@ nouveau_bo_del(struct nouveau_bo *bo) pthread_mutex_lock(&nvdev->lock); if (nvbo->name) { - if (atomic_read(&nvbo->refcnt)) { + if (atomic_read(&nvbo->refcnt) == 0) { + DRMLISTDEL(&nvbo->head); /* - * bo has been revived by a race with - * nouveau_bo_prime_handle_ref, or nouveau_bo_name_ref. - * - * In theory there's still a race possible with - * nouveau_bo_wrap, but when using this function - * the lifetime of the handle is probably already - * handled in another way. If there are races - * you're probably using nouveau_bo_wrap wrong. + * This bo has to be closed with the lock held because + * gem handles are not refcounted. If a shared bo is + * closed and re-opened in another thread a race + * against DRM_IOCTL_GEM_OPEN or drmPrimeFDToHandle + * might cause the bo to be closed accidentally while + * re-importing. */ - pthread_mutex_unlock(&nvdev->lock); - return; + drmIoctl(bo->device->fd, DRM_IOCTL_GEM_CLOSE, &req); } - DRMLISTDEL(&nvbo->head); - /* - * This bo has to be closed with the lock held because gem - * handles are not refcounted. If a shared bo is closed and - * re-opened in another thread a race against - * DRM_IOCTL_GEM_OPEN or drmPrimeFDToHandle might cause the - * bo to be closed accidentally while re-importing. - */ - drmIoctl(bo->device->fd, DRM_IOCTL_GEM_CLOSE, &req); pthread_mutex_unlock(&nvdev->lock); } else { DRMLISTDEL(&nvbo->head); @@ -418,7 +407,7 @@ nouveau_bo_new(struct nouveau_device *dev, uint32_t flags, uint32_t align, static int nouveau_bo_wrap_locked(struct nouveau_device *dev, uint32_t handle, - struct nouveau_bo **pbo) + struct nouveau_bo **pbo, int name) { struct nouveau_device_priv *nvdev = nouveau_device(dev); struct drm_nouveau_gem_info req = { .handle = handle }; @@ -427,8 +416,24 @@ nouveau_bo_wrap_locked(struct nouveau_device *dev, uint32_t handle, DRMLISTFOREACHENTRY(nvbo, &nvdev->bo_list, head) { if (nvbo->base.handle == handle) { - *pbo = NULL; - nouveau_bo_ref(&nvbo->base, pbo); + if (atomic_inc_return(&nvbo->refcnt) == 1) { + /* + * Uh oh, this bo is dead and someone else + * will free it, but because refcnt is + * now non-zero fortunately they won't + * call the ioctl to close the bo. + * + * Remove this bo from the list so other + * calls to nouveau_bo_wrap_locked will + * see our replacement nvbo. + */ + DRMLISTDEL(&nvbo->head); + if (!name) + name = nvbo->name; + break; + } + + *pbo = &nvbo->base; return 0; } } @@ -443,6 +448,7 @@ nouveau_bo_wrap_locked(struct nouveau_device *dev, uint32_t handle, atomic_set(&nvbo->refcnt, 1); nvbo->base.device = dev; abi16_bo_info(&nvbo->base, &req); + nvbo->name = name; DRMLISTADD(&nvbo->head, &nvdev->bo_list); *pbo = &nvbo->base; return 0; @@ -458,7 +464,7 @@ nouveau_bo_wrap(struct nouveau_device *dev, uint32_t handle, struct nouveau_device_priv *nvdev = nouveau_device(dev); int ret; pthread_mutex_lock(&nvdev->lock); - ret = nouveau_bo_wrap_locked(dev, handle, pbo); + ret = nouveau_bo_wrap_locked(dev, handle, pbo, 0); pthread_mutex_unlock(&nvdev->lock); return ret; } @@ -468,24 +474,13 @@ nouveau_bo_name_ref(struct nouveau_device *dev, uint32_t name, struct nouveau_bo **pbo) { struct nouveau_device_priv *nvdev = nouveau_device(dev); - struct nouveau_bo_priv *nvbo; struct drm_gem_open req = { .name = name }; int ret; pthread_mutex_lock(&nvdev->lock); - DRMLISTFOREACHENTRY(nvbo, &nvdev->bo_list, head) { - if (nvbo->name == name) { - *pbo = NULL; - nouveau_bo_ref(&nvbo->base, pbo); - pthread_mutex_unlock(&nvdev->lock); - return 0; - } - } - ret = drmIoctl(dev->fd, DRM_IOCTL_GEM_OPEN, &req); if (ret == 0) { - ret = nouveau_bo_wrap_locked(dev, req.handle, pbo); - nouveau_bo((*pbo))->name = name; + ret = nouveau_bo_wrap_locked(dev, req.handle, pbo, name); } pthread_mutex_unlock(&nvdev->lock); @@ -537,7 +532,7 @@ nouveau_bo_prime_handle_ref(struct nouveau_device *dev, int prime_fd, pthread_mutex_lock(&nvdev->lock); ret = drmPrimeFDToHandle(dev->fd, prime_fd, &handle); if (ret == 0) { - ret = nouveau_bo_wrap_locked(dev, handle, bo); + ret = nouveau_bo_wrap_locked(dev, handle, bo, 0); if (!ret) { struct nouveau_bo_priv *nvbo = nouveau_bo(*bo); if (!nvbo->name) { diff --git a/tests/Makefile.am b/tests/Makefile.am index d5269f9..94fcc08 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -31,6 +31,10 @@ check_PROGRAMS = \ dristat \ drmstat +if HAVE_NOUVEAU +SUBDIRS += nouveau +endif + if HAVE_LIBUDEV check_LTLIBRARIES = libdrmtest.la diff --git a/tests/nouveau/.gitignore b/tests/nouveau/.gitignore new file mode 100644 index 0000000..837bfb9 --- /dev/null +++ b/tests/nouveau/.gitignore @@ -0,0 +1 @@ +threaded diff --git a/tests/nouveau/Makefile.am b/tests/nouveau/Makefile.am new file mode 100644 index 0000000..c4f6e29 --- /dev/null +++ b/tests/nouveau/Makefile.am @@ -0,0 +1,16 @@ +AM_CPPFLAGS = \ + -I$(top_srcdir)/include/drm \ + -I$(top_srcdir)/nouveau \ + -I$(top_srcdir) + +AM_CFLAGS = $(WARN_CFLAGS) + +LDADD = \ + ../../nouveau/libdrm_nouveau.la \ + ../../libdrm.la \ + -ldl -lpthread + +TESTS = threaded + +check_PROGRAMS = $(TESTS) + diff --git a/tests/nouveau/threaded.c b/tests/nouveau/threaded.c new file mode 100644 index 0000000..281af46 --- /dev/null +++ b/tests/nouveau/threaded.c @@ -0,0 +1,156 @@ +/* + * Copyright © 2015 Canonical Ltd. (Maarten Lankhorst) + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + */ + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +#include +#include +#include +#include +#include +#include +#include + +#include "xf86drm.h" +#include "nouveau.h" + +static typeof(ioctl) *old_ioctl; +static int failed; + +static int import_fd; + +int ioctl(int fd, unsigned long request, ...) +{ + va_list va; + int ret; + void *arg; + + va_start(va, request); + arg = va_arg(va, void *); + ret = old_ioctl(fd, request, arg); + va_end(va); + + if (ret < 0 && request == DRM_IOCTL_GEM_CLOSE && errno == EINVAL) + failed = 1; + + return ret; +} + +static void * +openclose(void *dev) +{ + struct nouveau_device *nvdev = dev; + struct nouveau_bo *bo = NULL; + int i; + + for (i = 0; i < 100000; ++i) { + if (!nouveau_bo_prime_handle_ref(nvdev, import_fd, &bo)) + nouveau_bo_ref(NULL, &bo); + } + return NULL; +} + +int main(int argc, char *argv[]) +{ + drmVersionPtr version; + const char *device = NULL; + int err, fd, fd2; + struct nouveau_device *nvdev, *nvdev2; + struct nouveau_bo *bo; + pthread_t t1, t2; + + old_ioctl = dlsym(RTLD_NEXT, "ioctl"); + + if (argc < 2) { + fd = drmOpenWithType("nouveau", NULL, DRM_NODE_RENDER); + if (fd >= 0) + fd2 = drmOpenWithType("nouveau", NULL, DRM_NODE_RENDER); + } else { + device = argv[1]; + + fd = open(device, O_RDWR); + if (fd >= 0) + fd2 = open(device, O_RDWR); + else + fd2 = fd = -errno; + } + + if (fd < 0) { + fprintf(stderr, "Opening nouveau render node failed with %i\n", fd); + return device ? -fd : 77; + } + + if (fd2 < 0) { + fprintf(stderr, "Opening second nouveau render node failed with %i\n", -errno); + return errno; + } + + version = drmGetVersion(fd); + if (version) { + printf("Version: %d.%d.%d\n", version->version_major, + version->version_minor, version->version_patchlevel); + printf(" Name: %s\n", version->name); + printf(" Date: %s\n", version->date); + printf(" Description: %s\n", version->desc); + + drmFreeVersion(version); + } + + err = nouveau_device_wrap(fd, 0, &nvdev); + if (!err) + err = nouveau_device_wrap(fd2, 0, &nvdev2); + if (err < 0) + return 1; + + err = nouveau_bo_new(nvdev2, NOUVEAU_BO_GART, 0, 4096, NULL, &bo); + if (!err) + err = nouveau_bo_set_prime(bo, &import_fd); + + if (!err) { + pthread_create(&t1, NULL, openclose, nvdev); + pthread_create(&t2, NULL, openclose, nvdev); + } + + pthread_join(t1, NULL); + pthread_join(t2, NULL); + + close(import_fd); + nouveau_bo_ref(NULL, &bo); + + nouveau_device_del(&nvdev2); + nouveau_device_del(&nvdev); + if (device) { + close(fd2); + close(fd); + } else { + drmClose(fd2); + drmClose(fd); + } + + if (failed) + fprintf(stderr, "DRM_IOCTL_GEM_CLOSE failed with EINVAL,\n" + "race in opening/closing bo is likely.\n"); + + return failed; +} -- 2.7.4