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References: <20220309165222.2843651-1-tjmercier@google.com> <20220309165222.2843651-9-tjmercier@google.com>
In-Reply-To: <20220309165222.2843651-9-tjmercier@google.com>
From:   Todd Kjos <tkjos@google.com>
Date:   Mon, 14 Mar 2022 17:43:40 -0700
Message-ID: <CAHRSSEwN4Xuo2vLt8d2QfJbNOK21VB7_NjjbO_XGDz6pYUaXZg@mail.gmail.com>
Subject: Re: [RFC v3 8/8] selftests: Add binder cgroup gpu memory transfer test
To:     "T.J. Mercier" <tjmercier@google.com>
Cc:     Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jonathan Corbet <corbet@lwn.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <brauner@kernel.org>,
        Hridya Valsaraju <hridya@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        Benjamin Gaignard <benjamin.gaignard@linaro.org>,
        Liam Mark <lmark@codeaurora.org>,
        Laura Abbott <labbott@redhat.com>,
        Brian Starkey <Brian.Starkey@arm.com>,
        John Stultz <john.stultz@linaro.org>,
        Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Shuah Khan <shuah@kernel.org>, kaleshsingh@google.com,
        Kenny.Ho@amd.com, dri-devel@lists.freedesktop.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org
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On Wed, Mar 9, 2022 at 8:53 AM T.J. Mercier <tjmercier@google.com> wrote:
>
> This test verifies that the cgroup GPU memory charge is transferred
> correctly when a dmabuf is passed between processes in two different
> cgroups and the sender specifies BINDER_BUFFER_FLAG_SENDER_NO_NEED in the
> binder transaction data containing the dmabuf file descriptor.
>
> Signed-off-by: T.J. Mercier <tjmercier@google.com>

Reviewed-by: Todd Kjos <tkjos@google.com>
for the binder driver interactions. Need Christian to take a look at
the binderfs interactions.

> ---
>  .../selftests/drivers/android/binder/Makefile |   8 +
>  .../drivers/android/binder/binder_util.c      | 254 +++++++++
>  .../drivers/android/binder/binder_util.h      |  32 ++
>  .../selftests/drivers/android/binder/config   |   4 +
>  .../binder/test_dmabuf_cgroup_transfer.c      | 480 ++++++++++++++++++
>  5 files changed, 778 insertions(+)
>  create mode 100644 tools/testing/selftests/drivers/android/binder/Makefile
>  create mode 100644 tools/testing/selftests/drivers/android/binder/binder_util.c
>  create mode 100644 tools/testing/selftests/drivers/android/binder/binder_util.h
>  create mode 100644 tools/testing/selftests/drivers/android/binder/config
>  create mode 100644 tools/testing/selftests/drivers/android/binder/test_dmabuf_cgroup_transfer.c
>
> diff --git a/tools/testing/selftests/drivers/android/binder/Makefile b/tools/testing/selftests/drivers/android/binder/Makefile
> new file mode 100644
> index 000000000000..726439d10675
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/android/binder/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0
> +CFLAGS += -Wall
> +
> +TEST_GEN_PROGS = test_dmabuf_cgroup_transfer
> +
> +include ../../../lib.mk
> +
> +$(OUTPUT)/test_dmabuf_cgroup_transfer: ../../../cgroup/cgroup_util.c binder_util.c
> diff --git a/tools/testing/selftests/drivers/android/binder/binder_util.c b/tools/testing/selftests/drivers/android/binder/binder_util.c
> new file mode 100644
> index 000000000000..c9dcf5b9d42b
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/android/binder/binder_util.c
> @@ -0,0 +1,254 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "binder_util.h"
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <sys/mount.h>
> +
> +#include <linux/limits.h>
> +#include <linux/android/binder.h>
> +#include <linux/android/binderfs.h>
> +
> +static const size_t BINDER_MMAP_SIZE = 64 * 1024;
> +
> +static void binderfs_unmount(const char *mountpoint)
> +{
> +       if (umount2(mountpoint, MNT_DETACH))
> +               fprintf(stderr, "Failed to unmount binderfs at %s: %s\n",
> +                       mountpoint, strerror(errno));
> +       else
> +               fprintf(stderr, "Binderfs unmounted: %s\n", mountpoint);
> +
> +       if (rmdir(mountpoint))
> +               fprintf(stderr, "Failed to remove binderfs mount %s: %s\n",
> +                       mountpoint, strerror(errno));
> +       else
> +               fprintf(stderr, "Binderfs mountpoint destroyed: %s\n", mountpoint);
> +}
> +
> +struct binderfs_ctx create_binderfs(const char *name)
> +{
> +       int fd, ret, saved_errno;
> +       struct binderfs_device device = { 0 };
> +       struct binderfs_ctx ctx = { 0 };
> +
> +       /*
> +        * P_tmpdir is set to "/tmp/" on Android platforms where Binder is most
> +        * commonly used, but this path does not actually exist on Android. We
> +        * will first try using "/data/local/tmp" and fallback to P_tmpdir if
> +        * that fails for non-Android platforms.
> +        */
> +       static const char tmpdir[] = "/data/local/tmp";
> +       static const size_t MAX_TMPDIR_SIZE =
> +               sizeof(tmpdir) > sizeof(P_tmpdir) ?
> +               sizeof(tmpdir) : sizeof(P_tmpdir);
> +       static const char template[] = "/binderfs_XXXXXX";
> +
> +       char *mkdtemp_result;
> +       char binderfs_mntpt[MAX_TMPDIR_SIZE + sizeof(template)];
> +       char device_path[MAX_TMPDIR_SIZE + sizeof(template) + BINDERFS_MAX_NAME];
> +
> +       snprintf(binderfs_mntpt, sizeof(binderfs_mntpt), "%s%s", tmpdir, template);
> +
> +       mkdtemp_result = mkdtemp(binderfs_mntpt);
> +       if (mkdtemp_result == NULL) {
> +               fprintf(stderr, "Failed to create binderfs mountpoint at %s: %s.\n",
> +                       binderfs_mntpt, strerror(errno));
> +               fprintf(stderr, "Trying fallback mountpoint...\n");
> +               snprintf(binderfs_mntpt, sizeof(binderfs_mntpt), "%s%s", P_tmpdir, template);
> +               if (mkdtemp(binderfs_mntpt) == NULL) {
> +                       fprintf(stderr, "Failed to create binderfs mountpoint at %s: %s\n",
> +                       binderfs_mntpt, strerror(errno));
> +                       return ctx;
> +               }
> +       }
> +       fprintf(stderr, "Binderfs mountpoint created at %s\n", binderfs_mntpt);
> +
> +       if (mount(NULL, binderfs_mntpt, "binder", 0, 0)) {
> +               perror("Could not mount binderfs");
> +               rmdir(binderfs_mntpt);
> +               return ctx;
> +       }
> +       fprintf(stderr, "Binderfs mounted at %s\n", binderfs_mntpt);
> +
> +       strncpy(device.name, name, sizeof(device.name));
> +       snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
> +       fd = open(device_path, O_RDONLY | O_CLOEXEC);
> +       if (!fd) {
> +               perror("Failed to open binder-control device");
> +               binderfs_unmount(binderfs_mntpt);
> +               return ctx;
> +       }
> +
> +       ret = ioctl(fd, BINDER_CTL_ADD, &device);
> +       saved_errno = errno;
> +       close(fd);
> +       errno = saved_errno;
> +       if (ret) {
> +               perror("Failed to allocate new binder device");
> +               binderfs_unmount(binderfs_mntpt);
> +               return ctx;
> +       }
> +
> +       fprintf(stderr, "Allocated new binder device with major %d, minor %d, and name %s at %s\n",
> +               device.major, device.minor, device.name, binderfs_mntpt);
> +
> +       ctx.name = strdup(name);
> +       ctx.mountpoint = strdup(binderfs_mntpt);
> +       return ctx;
> +}
> +
> +void destroy_binderfs(struct binderfs_ctx *ctx)
> +{
> +       char path[PATH_MAX];
> +
> +       snprintf(path, sizeof(path), "%s/%s", ctx->mountpoint, ctx->name);
> +
> +       if (unlink(path))
> +               fprintf(stderr, "Failed to unlink binder device %s: %s\n", path, strerror(errno));
> +       else
> +               fprintf(stderr, "Destroyed binder %s at %s\n", ctx->name, ctx->mountpoint);
> +
> +       binderfs_unmount(ctx->mountpoint);
> +
> +       free(ctx->name);
> +       free(ctx->mountpoint);
> +}
> +
> +struct binder_ctx open_binder(struct binderfs_ctx *bfs_ctx)
> +{
> +       struct binder_ctx ctx = {.fd = -1, .memory = NULL};
> +       char path[PATH_MAX];
> +
> +       snprintf(path, sizeof(path), "%s/%s", bfs_ctx->mountpoint, bfs_ctx->name);
> +       ctx.fd = open(path, O_RDWR | O_NONBLOCK | O_CLOEXEC);
> +       if (ctx.fd < 0) {
> +               fprintf(stderr, "Error opening binder device %s: %s\n", path, strerror(errno));
> +               return ctx;
> +       }
> +
> +       ctx.memory = mmap(NULL, BINDER_MMAP_SIZE, PROT_READ, MAP_SHARED, ctx.fd, 0);
> +       if (ctx.memory == NULL) {
> +               perror("Error mapping binder memory");
> +               close(ctx.fd);
> +               ctx.fd = -1;
> +       }
> +
> +       return ctx;
> +}
> +
> +void close_binder(struct binder_ctx *ctx)
> +{
> +       if (munmap(ctx->memory, BINDER_MMAP_SIZE))
> +               perror("Failed to unmap binder memory");
> +       ctx->memory = NULL;
> +
> +       if (close(ctx->fd))
> +               perror("Failed to close binder");
> +       ctx->fd = -1;
> +}
> +
> +int become_binder_context_manager(int binder_fd)
> +{
> +       return ioctl(binder_fd, BINDER_SET_CONTEXT_MGR, 0);
> +}
> +
> +int do_binder_write_read(int binder_fd, void *writebuf, binder_size_t writesize,
> +                        void *readbuf, binder_size_t readsize)
> +{
> +       int err;
> +       struct binder_write_read bwr = {
> +               .write_buffer = (binder_uintptr_t)writebuf,
> +               .write_size = writesize,
> +               .read_buffer = (binder_uintptr_t)readbuf,
> +               .read_size = readsize
> +       };
> +
> +       do {
> +               if (ioctl(binder_fd, BINDER_WRITE_READ, &bwr) >= 0)
> +                       err = 0;
> +               else
> +                       err = -errno;
> +       } while (err == -EINTR);
> +
> +       if (err < 0) {
> +               perror("BINDER_WRITE_READ");
> +               return -1;
> +       }
> +
> +       if (bwr.write_consumed < writesize) {
> +               fprintf(stderr, "Binder did not consume full write buffer %llu %llu\n",
> +                       bwr.write_consumed, writesize);
> +               return -1;
> +       }
> +
> +       return bwr.read_consumed;
> +}
> +
> +static const char *reply_string(int cmd)
> +{
> +       switch (cmd) {
> +       case BR_ERROR:
> +               return("BR_ERROR");
> +       case BR_OK:
> +               return("BR_OK");
> +       case BR_TRANSACTION_SEC_CTX:
> +               return("BR_TRANSACTION_SEC_CTX");
> +       case BR_TRANSACTION:
> +               return("BR_TRANSACTION");
> +       case BR_REPLY:
> +               return("BR_REPLY");
> +       case BR_ACQUIRE_RESULT:
> +               return("BR_ACQUIRE_RESULT");
> +       case BR_DEAD_REPLY:
> +               return("BR_DEAD_REPLY");
> +       case BR_TRANSACTION_COMPLETE:
> +               return("BR_TRANSACTION_COMPLETE");
> +       case BR_INCREFS:
> +               return("BR_INCREFS");
> +       case BR_ACQUIRE:
> +               return("BR_ACQUIRE");
> +       case BR_RELEASE:
> +               return("BR_RELEASE");
> +       case BR_DECREFS:
> +               return("BR_DECREFS");
> +       case BR_ATTEMPT_ACQUIRE:
> +               return("BR_ATTEMPT_ACQUIRE");
> +       case BR_NOOP:
> +               return("BR_NOOP");
> +       case BR_SPAWN_LOOPER:
> +               return("BR_SPAWN_LOOPER");
> +       case BR_FINISHED:
> +               return("BR_FINISHED");
> +       case BR_DEAD_BINDER:
> +               return("BR_DEAD_BINDER");
> +       case BR_CLEAR_DEATH_NOTIFICATION_DONE:
> +               return("BR_CLEAR_DEATH_NOTIFICATION_DONE");
> +       case BR_FAILED_REPLY:
> +               return("BR_FAILED_REPLY");
> +       case BR_FROZEN_REPLY:
> +               return("BR_FROZEN_REPLY");
> +       case BR_ONEWAY_SPAM_SUSPECT:
> +               return("BR_ONEWAY_SPAM_SUSPECT");
> +       default:
> +               return("Unknown");
> +       };
> +}
> +
> +int expect_binder_reply(int32_t actual, int32_t expected)
> +{
> +       if (actual != expected) {
> +               fprintf(stderr, "Expected %s but received %s\n",
> +                       reply_string(expected), reply_string(actual));
> +               return -1;
> +       }
> +       return 0;
> +}
> +
> diff --git a/tools/testing/selftests/drivers/android/binder/binder_util.h b/tools/testing/selftests/drivers/android/binder/binder_util.h
> new file mode 100644
> index 000000000000..807f5abe987e
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/android/binder/binder_util.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef SELFTEST_BINDER_UTIL_H
> +#define SELFTEST_BINDER_UTIL_H
> +
> +#include <stdint.h>
> +
> +#include <linux/android/binder.h>
> +
> +struct binderfs_ctx {
> +       char *name;
> +       char *mountpoint;
> +};
> +
> +struct binder_ctx {
> +       int fd;
> +       void *memory;
> +};
> +
> +struct binderfs_ctx create_binderfs(const char *name);
> +void destroy_binderfs(struct binderfs_ctx *ctx);
> +
> +struct binder_ctx open_binder(struct binderfs_ctx *bfs_ctx);
> +void close_binder(struct binder_ctx *ctx);
> +
> +int become_binder_context_manager(int binder_fd);
> +
> +int do_binder_write_read(int binder_fd, void *writebuf, binder_size_t writesize,
> +                        void *readbuf, binder_size_t readsize);
> +
> +int expect_binder_reply(int32_t actual, int32_t expected);
> +#endif
> diff --git a/tools/testing/selftests/drivers/android/binder/config b/tools/testing/selftests/drivers/android/binder/config
> new file mode 100644
> index 000000000000..fcc5f8f693b3
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/android/binder/config
> @@ -0,0 +1,4 @@
> +CONFIG_CGROUP_GPU=y
> +CONFIG_ANDROID=y
> +CONFIG_ANDROID_BINDERFS=y
> +CONFIG_ANDROID_BINDER_IPC=y
> diff --git a/tools/testing/selftests/drivers/android/binder/test_dmabuf_cgroup_transfer.c b/tools/testing/selftests/drivers/android/binder/test_dmabuf_cgroup_transfer.c
> new file mode 100644
> index 000000000000..9b952ab401cc
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/android/binder/test_dmabuf_cgroup_transfer.c
> @@ -0,0 +1,480 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * This test verifies that the cgroup GPU memory charge is transferred correctly
> + * when a dmabuf is passed between processes in two different cgroups and the
> + * sender specifies BINDER_BUFFER_FLAG_SENDER_NO_NEED in the binder transaction
> + * data containing the dmabuf file descriptor.
> + *
> + * The gpu_cgroup_dmabuf_transfer test function becomes the binder context
> + * manager, then forks a child who initiates a transaction with the context
> + * manager by specifying a target of 0. The context manager reply contains a
> + * dmabuf file descriptor which was allocated by the gpu_cgroup_dmabuf_transfer
> + * test function, but should be charged to the child cgroup after the binder
> + * transaction.
> + */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stddef.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/epoll.h>
> +#include <sys/ioctl.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +
> +#include "binder_util.h"
> +#include "../../../cgroup/cgroup_util.h"
> +#include "../../../kselftest.h"
> +#include "../../../kselftest_harness.h"
> +
> +#include <linux/limits.h>
> +#include <linux/dma-heap.h>
> +#include <linux/android/binder.h>
> +
> +#define UNUSED(x) ((void)(x))
> +
> +static const unsigned int BINDER_CODE = 8675309; /* Any number will work here */
> +
> +struct cgroup_ctx {
> +       char *root;
> +       char *source;
> +       char *dest;
> +};
> +
> +void destroy_cgroups(struct __test_metadata *_metadata, struct cgroup_ctx *ctx)
> +{
> +       if (ctx->source != NULL) {
> +               TH_LOG("Destroying cgroup: %s", ctx->source);
> +               rmdir(ctx->source);
> +               free(ctx->source);
> +       }
> +
> +       if (ctx->dest != NULL) {
> +               TH_LOG("Destroying cgroup: %s", ctx->dest);
> +               rmdir(ctx->dest);
> +               free(ctx->dest);
> +       }
> +
> +       free(ctx->root);
> +       ctx->root = ctx->source = ctx->dest = NULL;
> +}
> +
> +struct cgroup_ctx create_cgroups(struct __test_metadata *_metadata)
> +{
> +       struct cgroup_ctx ctx = {0};
> +       char root[PATH_MAX], *tmp;
> +       static const char template[] = "/gpucg_XXXXXX";
> +
> +       if (cg_find_unified_root(root, sizeof(root))) {
> +               TH_LOG("Could not find cgroups root");
> +               return ctx;
> +       }
> +
> +       if (cg_read_strstr(root, "cgroup.controllers", "gpu")) {
> +               TH_LOG("Could not find GPU controller");
> +               return ctx;
> +       }
> +
> +       if (cg_write(root, "cgroup.subtree_control", "+gpu")) {
> +               TH_LOG("Could not enable GPU controller");
> +               return ctx;
> +       }
> +
> +       ctx.root = strdup(root);
> +
> +       snprintf(root, sizeof(root), "%s/%s", ctx.root, template);
> +       tmp = mkdtemp(root);
> +       if (tmp == NULL) {
> +               TH_LOG("%s - Could not create source cgroup", strerror(errno));
> +               destroy_cgroups(_metadata, &ctx);
> +               return ctx;
> +       }
> +       ctx.source = strdup(tmp);
> +
> +       snprintf(root, sizeof(root), "%s/%s", ctx.root, template);
> +       tmp = mkdtemp(root);
> +       if (tmp == NULL) {
> +               TH_LOG("%s - Could not create destination cgroup", strerror(errno));
> +               destroy_cgroups(_metadata, &ctx);
> +               return ctx;
> +       }
> +       ctx.dest = strdup(tmp);
> +
> +       TH_LOG("Created cgroups: %s %s", ctx.source, ctx.dest);
> +
> +       return ctx;
> +}
> +
> +int dmabuf_heap_alloc(int fd, size_t len, int *dmabuf_fd)
> +{
> +       struct dma_heap_allocation_data data = {
> +               .len = len,
> +               .fd = 0,
> +               .fd_flags = O_RDONLY | O_CLOEXEC,
> +               .heap_flags = 0,
> +       };
> +       int ret;
> +
> +       if (!dmabuf_fd)
> +               return -EINVAL;
> +
> +       ret = ioctl(fd, DMA_HEAP_IOCTL_ALLOC, &data);
> +       if (ret < 0)
> +               return ret;
> +       *dmabuf_fd = (int)data.fd;
> +       return ret;
> +}
> +
> +/* The system heap is known to export dmabufs with support for cgroup tracking */
> +int alloc_dmabuf_from_system_heap(struct __test_metadata *_metadata, size_t bytes)
> +{
> +       int heap_fd = -1, dmabuf_fd = -1;
> +       static const char * const heap_path = "/dev/dma_heap/system";
> +
> +       heap_fd = open(heap_path, O_RDONLY);
> +       if (heap_fd < 0) {
> +               TH_LOG("%s - open %s failed!\n", strerror(errno), heap_path);
> +               return -1;
> +       }
> +
> +       if (dmabuf_heap_alloc(heap_fd, bytes, &dmabuf_fd))
> +               TH_LOG("dmabuf allocation failed! - %s", strerror(errno));
> +       close(heap_fd);
> +
> +       return dmabuf_fd;
> +}
> +
> +int binder_request_dmabuf(int binder_fd)
> +{
> +       int ret;
> +
> +       /*
> +        * We just send an empty binder_buffer_object to initiate a transaction
> +        * with the context manager, who should respond with a single dmabuf
> +        * inside a binder_fd_array_object.
> +        */
> +
> +       struct binder_buffer_object bbo = {
> +               .hdr.type = BINDER_TYPE_PTR,
> +               .flags = 0,
> +               .buffer = 0,
> +               .length = 0,
> +               .parent = 0, /* No parent */
> +               .parent_offset = 0 /* No parent */
> +       };
> +
> +       binder_size_t offsets[] = {0};
> +
> +       struct {
> +               int32_t cmd;
> +               struct binder_transaction_data btd;
> +       } __attribute__((packed)) bc = {
> +               .cmd = BC_TRANSACTION,
> +               .btd = {
> +                       .target = { 0 },
> +                       .cookie = 0,
> +                       .code = BINDER_CODE,
> +                       .flags = TF_ACCEPT_FDS, /* We expect a FDA in the reply */
> +                       .data_size = sizeof(bbo),
> +                       .offsets_size = sizeof(offsets),
> +                       .data.ptr = {
> +                               (binder_uintptr_t)&bbo,
> +                               (binder_uintptr_t)offsets
> +                       }
> +               },
> +       };
> +
> +       struct {
> +               int32_t reply_noop;
> +       } __attribute__((packed)) br;
> +
> +       ret = do_binder_write_read(binder_fd, &bc, sizeof(bc), &br, sizeof(br));
> +       if (ret >= sizeof(br) && expect_binder_reply(br.reply_noop, BR_NOOP)) {
> +               return -1;
> +       } else if (ret < sizeof(br)) {
> +               fprintf(stderr, "Not enough bytes in binder reply %d\n", ret);
> +               return -1;
> +       }
> +       return 0;
> +}
> +
> +int send_dmabuf_reply(int binder_fd, struct binder_transaction_data *tr, int dmabuf_fd)
> +{
> +       int ret;
> +       /*
> +        * The trailing 0 is to achieve the necessary alignment for the binder
> +        * buffer_size.
> +        */
> +       int fdarray[] = { dmabuf_fd, 0 };
> +
> +       struct binder_buffer_object bbo = {
> +               .hdr.type = BINDER_TYPE_PTR,
> +               .flags = BINDER_BUFFER_FLAG_SENDER_NO_NEED,
> +               .buffer = (binder_uintptr_t)fdarray,
> +               .length = sizeof(fdarray),
> +               .parent = 0, /* No parent */
> +               .parent_offset = 0 /* No parent */
> +       };
> +
> +       struct binder_fd_array_object bfdao = {
> +               .hdr.type = BINDER_TYPE_FDA,
> +               .num_fds = 1,
> +               .parent = 0, /* The binder_buffer_object */
> +               .parent_offset = 0 /* FDs follow immediately */
> +       };
> +
> +       uint64_t sz = sizeof(fdarray);
> +       uint8_t data[sizeof(sz) + sizeof(bbo) + sizeof(bfdao)];
> +       binder_size_t offsets[] = {sizeof(sz), sizeof(sz)+sizeof(bbo)};
> +
> +       memcpy(data,                            &sz, sizeof(sz));
> +       memcpy(data + sizeof(sz),               &bbo, sizeof(bbo));
> +       memcpy(data + sizeof(sz) + sizeof(bbo), &bfdao, sizeof(bfdao));
> +
> +       struct {
> +               int32_t cmd;
> +               struct binder_transaction_data_sg btd;
> +       } __attribute__((packed)) bc = {
> +               .cmd = BC_REPLY_SG,
> +               .btd.transaction_data = {
> +                       .target = { tr->target.handle },
> +                       .cookie = tr->cookie,
> +                       .code = BINDER_CODE,
> +                       .flags = 0,
> +                       .data_size = sizeof(data),
> +                       .offsets_size = sizeof(offsets),
> +                       .data.ptr = {
> +                               (binder_uintptr_t)data,
> +                               (binder_uintptr_t)offsets
> +                       }
> +               },
> +               .btd.buffers_size = sizeof(fdarray)
> +       };
> +
> +       struct {
> +               int32_t reply_noop;
> +       } __attribute__((packed)) br;
> +
> +       ret = do_binder_write_read(binder_fd, &bc, sizeof(bc), &br, sizeof(br));
> +       if (ret >= sizeof(br) && expect_binder_reply(br.reply_noop, BR_NOOP)) {
> +               return -1;
> +       } else if (ret < sizeof(br)) {
> +               fprintf(stderr, "Not enough bytes in binder reply %d\n", ret);
> +               return -1;
> +       }
> +       return 0;
> +}
> +
> +struct binder_transaction_data *binder_wait_for_transaction(int binder_fd,
> +                                                           uint32_t *readbuf,
> +                                                           size_t readsize)
> +{
> +       static const int MAX_EVENTS = 1, EPOLL_WAIT_TIME_MS = 3 * 1000;
> +       struct binder_reply {
> +               int32_t reply0;
> +               int32_t reply1;
> +               struct binder_transaction_data btd;
> +       } *br;
> +       struct binder_transaction_data *ret = NULL;
> +       struct epoll_event events[MAX_EVENTS];
> +       int epoll_fd, num_events, readcount;
> +       uint32_t bc[] = { BC_ENTER_LOOPER };
> +
> +       do_binder_write_read(binder_fd, &bc, sizeof(bc), NULL, 0);
> +
> +       epoll_fd = epoll_create1(EPOLL_CLOEXEC);
> +       if (epoll_fd == -1) {
> +               perror("epoll_create");
> +               return NULL;
> +       }
> +
> +       events[0].events = EPOLLIN;
> +       if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, binder_fd, &events[0])) {
> +               perror("epoll_ctl add");
> +               goto err_close;
> +       }
> +
> +       num_events = epoll_wait(epoll_fd, events, MAX_EVENTS, EPOLL_WAIT_TIME_MS);
> +       if (num_events < 0) {
> +               perror("epoll_wait");
> +               goto err_ctl;
> +       } else if (num_events == 0) {
> +               fprintf(stderr, "No events\n");
> +               goto err_ctl;
> +       }
> +
> +       readcount = do_binder_write_read(binder_fd, NULL, 0, readbuf, readsize);
> +       fprintf(stderr, "Read %d bytes from binder\n", readcount);
> +
> +       if (readcount < (int)sizeof(struct binder_reply)) {
> +               fprintf(stderr, "read_consumed not large enough\n");
> +               goto err_ctl;
> +       }
> +
> +       br = (struct binder_reply *)readbuf;
> +       if (expect_binder_reply(br->reply0, BR_NOOP))
> +               goto err_ctl;
> +
> +       if (br->reply1 == BR_TRANSACTION) {
> +               if (br->btd.code == BINDER_CODE)
> +                       ret = &br->btd;
> +               else
> +                       fprintf(stderr, "Received transaction with unexpected code: %u\n",
> +                               br->btd.code);
> +       } else {
> +               expect_binder_reply(br->reply1, BR_TRANSACTION_COMPLETE);
> +       }
> +
> +err_ctl:
> +       if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, binder_fd, NULL))
> +               perror("epoll_ctl del");
> +err_close:
> +       close(epoll_fd);
> +       return ret;
> +}
> +
> +static int child_request_dmabuf_transfer(const char *cgroup, void *arg)
> +{
> +       UNUSED(cgroup);
> +       int ret = -1;
> +       uint32_t readbuf[32];
> +       struct binderfs_ctx bfs_ctx = *(struct binderfs_ctx *)arg;
> +       struct binder_ctx b_ctx;
> +
> +       fprintf(stderr, "Child PID: %d\n", getpid());
> +
> +       b_ctx = open_binder(&bfs_ctx);
> +       if (b_ctx.fd < 0) {
> +               fprintf(stderr, "Child unable to open binder\n");
> +               return -1;
> +       }
> +
> +       if (binder_request_dmabuf(b_ctx.fd))
> +               goto err;
> +
> +       /* The child must stay alive until the binder reply is received */
> +       if (binder_wait_for_transaction(b_ctx.fd, readbuf, sizeof(readbuf)) == NULL)
> +               ret = 0;
> +
> +       /*
> +        * We don't close the received dmabuf here so that the parent can
> +        * inspect the cgroup gpu memory charges to verify the charge transfer
> +        * completed successfully.
> +        */
> +err:
> +       close_binder(&b_ctx);
> +       fprintf(stderr, "Child done\n");
> +       return ret;
> +}
> +
> +TEST(gpu_cgroup_dmabuf_transfer)
> +{
> +       static const char * const GPUMEM_FILENAME = "gpu.memory.current";
> +       static const size_t ONE_MiB = 1024 * 1024;
> +
> +       int ret, dmabuf_fd;
> +       uint32_t readbuf[32];
> +       long memsize;
> +       pid_t child_pid;
> +       struct binderfs_ctx bfs_ctx;
> +       struct binder_ctx b_ctx;
> +       struct cgroup_ctx cg_ctx;
> +       struct binder_transaction_data *tr;
> +       struct flat_binder_object *fbo;
> +       struct binder_buffer_object *bbo;
> +
> +       bfs_ctx = create_binderfs("testbinder");
> +       if (bfs_ctx.name == NULL)
> +               ksft_exit_skip("The Android binderfs filesystem is not available\n");
> +
> +       cg_ctx = create_cgroups(_metadata);
> +       if (cg_ctx.root == NULL) {
> +               destroy_binderfs(&bfs_ctx);
> +               ksft_exit_skip("cgroup v2 isn't mounted\n");
> +       }
> +
> +       ASSERT_EQ(cg_enter_current(cg_ctx.source), 0) {
> +               TH_LOG("Could not move parent to cgroup: %s", cg_ctx.source);
> +               goto err_cg;
> +       }
> +
> +       dmabuf_fd = alloc_dmabuf_from_system_heap(_metadata, ONE_MiB);
> +       ASSERT_GE(dmabuf_fd, 0) {
> +               goto err_cg;
> +       }
> +       TH_LOG("Allocated dmabuf");
> +
> +       memsize = cg_read_key_long(cg_ctx.source, GPUMEM_FILENAME, "system");
> +       ASSERT_EQ(memsize, ONE_MiB) {
> +               TH_LOG("GPU memory used after allocation: %ld but it should be %lu",
> +                      memsize, (unsigned long)ONE_MiB);
> +               goto err_dmabuf;
> +       }
> +
> +       b_ctx = open_binder(&bfs_ctx);
> +       ASSERT_GE(b_ctx.fd, 0) {
> +               TH_LOG("Parent unable to open binder");
> +               goto err_dmabuf;
> +       }
> +       TH_LOG("Opened binder at %s/%s", bfs_ctx.mountpoint, bfs_ctx.name);
> +
> +       ASSERT_EQ(become_binder_context_manager(b_ctx.fd), 0) {
> +               TH_LOG("Cannot become context manager: %s", strerror(errno));
> +               goto err_binder;
> +       }
> +
> +       child_pid = cg_run_nowait(cg_ctx.dest, child_request_dmabuf_transfer, &bfs_ctx);
> +       ASSERT_GT(child_pid, 0) {
> +               TH_LOG("Error forking: %s", strerror(errno));
> +               goto err_binder;
> +       }
> +
> +       tr = binder_wait_for_transaction(b_ctx.fd, readbuf, sizeof(readbuf));
> +       ASSERT_NE(tr, NULL) {
> +               TH_LOG("Error receiving transaction request from child");
> +               goto err_child;
> +       }
> +       fbo = (struct flat_binder_object *)tr->data.ptr.buffer;
> +       ASSERT_EQ(fbo->hdr.type, BINDER_TYPE_PTR) {
> +               TH_LOG("Did not receive a buffer object from child");
> +               goto err_child;
> +       }
> +       bbo = (struct binder_buffer_object *)fbo;
> +       ASSERT_EQ(bbo->length, 0) {
> +               TH_LOG("Did not receive an empty buffer object from child");
> +               goto err_child;
> +       }
> +
> +       TH_LOG("Received transaction from child");
> +       send_dmabuf_reply(b_ctx.fd, tr, dmabuf_fd);
> +
> +       ASSERT_EQ(cg_read_key_long(cg_ctx.dest, GPUMEM_FILENAME, "system"), ONE_MiB) {
> +               TH_LOG("Destination cgroup does not have system charge!");
> +               goto err_child;
> +       }
> +       ASSERT_EQ(cg_read_key_long(cg_ctx.source, GPUMEM_FILENAME, "system"), 0) {
> +               TH_LOG("Source cgroup still has system charge!");
> +               goto err_child;
> +       }
> +       TH_LOG("Charge transfer succeeded!");
> +
> +err_child:
> +       waitpid(child_pid, &ret, 0);
> +       if (WIFEXITED(ret))
> +               TH_LOG("Child %d terminated with %d", child_pid, WEXITSTATUS(ret));
> +       else
> +               TH_LOG("Child terminated abnormally");
> +err_binder:
> +       close_binder(&b_ctx);
> +err_dmabuf:
> +       close(dmabuf_fd);
> +err_cg:
> +       destroy_cgroups(_metadata, &cg_ctx);
> +       destroy_binderfs(&bfs_ctx);
> +}
> +
> +TEST_HARNESS_MAIN
> --
> 2.35.1.616.g0bdcbb4464-goog
>