Re: [RFC v3 8/8] selftests: Add binder cgroup gpu memory transfer test

["T.J. Mercier" <tjmercier@google.com>]

On Wed, Mar 9, 2022 at 1:31 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> On 3/9/22 9:52 AM, T.J. Mercier 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>
> > ---
> >   .../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
> > +
>
> Does this test inteded to be built on all architectures? Is arch
> check necessary here?

I think this test should be runnable on any architecture, so long as
the correct kernel configs (for binder and cgroups) are enabled. I
have tested it on arm64 and x86-64.

>
> Also does this test require root previleges - I see mount and
> unmount operations in the test. If so add root check and skip
> if non-root user runs the test.

Yes, currently it does. Thanks, I will add this check at the location
you have pointed out in the TEST function.

>
> > +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);
>
> Does umount require root previleges? Same commment as above about
> non-root user running test.
>
>
> > +}
> > +
> > +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);
>
> Does mount require root previleges? Same commment as above about
> non-root user running test.
>
> > +
> > +     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));
>
> Does this require root previleges?
>
> > +             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;
> > +     }
>
> Same question about root preveliges?
>
> > +
> > +     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;
> > +
>
> If root previges is necessary - pls add check here and skip.
>
> > +     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");
>
> What does this mean? What are the conditions that could cause this?
> Pls include more info. in the message.

This would be very unusual, but possible if the child is
(accidentally?) killed by a user or the low/out of memory killer. It
looks like I can add more information with the WIFSIGNALED and
WTERMSIG macros, so I will do that.

>
> > +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
> >
>
> thanks,
> -- Shuah

Thanks for taking a look!