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Subject[PATCH v5 14/14] kselftest: add uepoll-test which tests polling from userspace
Date
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/uepoll/.gitignore | 1 +
tools/testing/selftests/uepoll/Makefile | 16 +
.../uepoll/atomic-builtins-support.c | 13 +
tools/testing/selftests/uepoll/uepoll-test.c | 603 ++++++++++++++++++
5 files changed, 634 insertions(+)
create mode 100644 tools/testing/selftests/uepoll/.gitignore
create mode 100644 tools/testing/selftests/uepoll/Makefile
create mode 100644 tools/testing/selftests/uepoll/atomic-builtins-support.c
create mode 100644 tools/testing/selftests/uepoll/uepoll-test.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 9781ca79794a..ff87ac3400fe 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -52,6 +52,7 @@ TARGETS += timers
endif
TARGETS += tmpfs
TARGETS += tpm2
+TARGETS += uepoll
TARGETS += user
TARGETS += vm
TARGETS += x86
diff --git a/tools/testing/selftests/uepoll/.gitignore b/tools/testing/selftests/uepoll/.gitignore
new file mode 100644
index 000000000000..8eedec333023
--- /dev/null
+++ b/tools/testing/selftests/uepoll/.gitignore
@@ -0,0 +1 @@
+uepoll-test
diff --git a/tools/testing/selftests/uepoll/Makefile b/tools/testing/selftests/uepoll/Makefile
new file mode 100644
index 000000000000..cc1b2009197d
--- /dev/null
+++ b/tools/testing/selftests/uepoll/Makefile
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CC := $(CROSS_COMPILE)gcc
+CFLAGS += -O2 -g -I../../../../usr/include/ -lnuma -lpthread
+
+BUILTIN_SUPPORT := $(shell $(CC) -o /dev/null ./atomic-builtins-support.c >/dev/null 2>&1; echo $$?)
+
+ifeq "$(BUILTIN_SUPPORT)" "0"
+ TEST_GEN_PROGS := uepoll-test
+else
+ $(warning WARNING:)
+ $(warning WARNING: uepoll compilation is skipped, gcc atomic builtins are not supported!)
+ $(warning WARNING:)
+endif
+
+include ../lib.mk
diff --git a/tools/testing/selftests/uepoll/atomic-builtins-support.c b/tools/testing/selftests/uepoll/atomic-builtins-support.c
new file mode 100644
index 000000000000..d9ded39ec497
--- /dev/null
+++ b/tools/testing/selftests/uepoll/atomic-builtins-support.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Just a test to check if gcc supports atomic builtins
+ */
+unsigned long long v, vv, vvv;
+
+int main(void)
+{
+ vv = __atomic_load_n(&v, __ATOMIC_ACQUIRE);
+ vvv = __atomic_exchange_n(&vv, 0, __ATOMIC_ACQUIRE);
+
+ return __atomic_add_fetch(&vvv, 1, __ATOMIC_RELAXED);
+}
diff --git a/tools/testing/selftests/uepoll/uepoll-test.c b/tools/testing/selftests/uepoll/uepoll-test.c
new file mode 100644
index 000000000000..1cefdcc1e25b
--- /dev/null
+++ b/tools/testing/selftests/uepoll/uepoll-test.c
@@ -0,0 +1,603 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * uepoll-test.c - Test cases for epoll_create2(), namely pollable
+ * epoll from userspace. Copyright (c) 2019 Roman Penyaev
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <errno.h>
+#include <syscall.h>
+#include <numa.h>
+
+#include "../kselftest.h"
+#include "../kselftest_harness.h"
+
+#include <linux/eventpoll.h>
+#include <linux/types.h>
+
+#define BUILD_BUG_ON(condition) ((void)sizeof(char [1 - 2*!!(condition)]))
+#define READ_ONCE(v) (*(volatile typeof(v)*)&(v))
+
+#define ITERS 1000000ull
+
+/*
+ * Add main epoll functions manually, because sys/epoll.h conflicts
+ * with linux/eventpoll.h.
+ */
+extern int epoll_create1(int __flags);
+extern int epoll_ctl(int __epfd, int __op, int __fd,
+ struct epoll_event *__event);
+extern int epoll_wait(int __epfd, struct epoll_event *__events,
+ int __maxevents, int __timeout);
+
+static inline long epoll_create2(int flags, size_t size)
+{
+ return syscall(__NR_epoll_create2, flags, size);
+}
+
+struct thread_ctx {
+ pthread_t thread;
+ int efd;
+};
+
+struct cpu_map {
+ unsigned int nr;
+ unsigned int map[];
+};
+
+static volatile unsigned int thr_ready;
+static volatile unsigned int start;
+
+static inline unsigned int max_index_nr(struct epoll_uheader *header)
+{
+ return header->index_length >> 2;
+}
+
+static int is_cpu_online(int cpu)
+{
+ char buf[64];
+ char online;
+ FILE *f;
+ int rc;
+
+ snprintf(buf, sizeof(buf), "/sys/devices/system/cpu/cpu%d/online", cpu);
+ f = fopen(buf, "r");
+ if (!f)
+ return 1;
+
+ rc = fread(&online, 1, 1, f);
+ assert(rc == 1);
+ fclose(f);
+
+ return (char)online == '1';
+}
+
+static struct cpu_map *cpu_map__new(void)
+{
+ struct cpu_map *cpu;
+ struct bitmask *bm;
+
+ int i, bit, cpus_nr;
+
+ cpus_nr = numa_num_possible_cpus();
+ cpu = calloc(1, sizeof(*cpu) + sizeof(cpu->map[0]) * cpus_nr);
+ if (!cpu)
+ return NULL;
+
+ bm = numa_all_cpus_ptr;
+ assert(bm);
+
+ for (bit = 0, i = 0; bit < bm->size; bit++) {
+ if (numa_bitmask_isbitset(bm, bit) && is_cpu_online(bit)) {
+ cpu->map[i++] = bit;
+ }
+ }
+ cpu->nr = i;
+
+ return cpu;
+}
+
+static void cpu_map__put(struct cpu_map *cpu)
+{
+ free(cpu);
+}
+
+static inline unsigned long long nsecs(void)
+{
+ struct timespec ts = {0, 0};
+
+ clock_gettime(CLOCK_MONOTONIC, &ts);
+ return ((unsigned long long)ts.tv_sec * 1000000000ull) + ts.tv_nsec;
+}
+
+static void *thread_work(void *arg)
+{
+ struct thread_ctx *ctx = arg;
+ uint64_t ucnt = 1;
+ unsigned int i;
+ int rc;
+
+ __atomic_add_fetch(&thr_ready, 1, __ATOMIC_RELAXED);
+
+ while (!start)
+ ;
+
+ for (i = 0; i < ITERS; i++) {
+ rc = write(ctx->efd, &ucnt, sizeof(ucnt));
+ assert(rc == sizeof(ucnt));
+ }
+
+ return NULL;
+}
+
+static inline _Bool read_event(struct epoll_uheader *header,
+ unsigned int *index, unsigned int idx,
+ struct epoll_event *event)
+{
+ struct epoll_uitem *item;
+ unsigned int *item_idx_ptr;
+ unsigned int indeces_mask;
+
+ indeces_mask = max_index_nr(header) - 1;
+ if (indeces_mask & max_index_nr(header)) {
+ assert(0);
+ /* Should be pow2, corrupted header? */
+ return 0;
+ }
+
+ item_idx_ptr = &index[idx & indeces_mask];
+
+ /* Load index */
+ idx = __atomic_load_n(item_idx_ptr, __ATOMIC_ACQUIRE);
+ if (idx >= header->max_items_nr) {
+ assert(0);
+ /* Corrupted index? */
+ return 0;
+ }
+
+ item = &header->items[idx];
+
+ /*
+ * Fetch data first, if event is cleared by the kernel we drop the data
+ * returning false.
+ */
+ event->data = (__u64) item->data;
+ event->events = __atomic_exchange_n(&item->ready_events, 0,
+ __ATOMIC_RELEASE);
+
+ return (event->events & ~EPOLLREMOVED);
+}
+
+static int uepoll_wait(struct epoll_uheader *header, unsigned int *index,
+ int epfd, struct epoll_event *events, int maxevents)
+
+{
+ /*
+ * Before entering kernel we do busy wait for ~1ms, naively assuming
+ * each iteration costs 1 cycle, 1 ns.
+ */
+ unsigned int spins = 1000000;
+ unsigned int tail;
+ int i;
+
+ assert(maxevents > 0);
+
+again:
+ /*
+ * Cache the tail because we don't want refetch it on each iteration
+ * and then catch live events updates, i.e. we don't want user @events
+ * array consist of events from the same fds.
+ */
+ tail = READ_ONCE(header->tail);
+
+ if (header->head == tail) {
+ if (spins--)
+ /* Busy loop a bit */
+ goto again;
+
+ i = epoll_wait(epfd, NULL, 0, -1);
+ assert(i < 0);
+ if (errno != ESTALE)
+ return i;
+
+ tail = READ_ONCE(header->tail);
+ assert(header->head != tail);
+ }
+
+ for (i = 0; header->head != tail && i < maxevents; header->head++) {
+ if (read_event(header, index, header->head, &events[i]))
+ i++;
+ else
+ /* Event can't be removed under us */
+ assert(0);
+ }
+
+ return i;
+}
+
+static void uepoll_mmap(int epfd, struct epoll_uheader **_header,
+ unsigned int **_index)
+{
+ struct epoll_uheader *header;
+ unsigned int *index, len;
+
+ BUILD_BUG_ON(sizeof(*header) != EPOLL_USERPOLL_HEADER_SIZE);
+ BUILD_BUG_ON(sizeof(header->items[0]) != 16);
+
+ len = sysconf(_SC_PAGESIZE);
+again:
+ header = mmap(NULL, len, PROT_WRITE|PROT_READ, MAP_SHARED, epfd, 0);
+ if (header == MAP_FAILED)
+ ksft_exit_fail_msg("Failed map(header)\n");
+
+ if (header->header_length != len) {
+ unsigned int tmp_len = len;
+
+ len = header->header_length;
+ munmap(header, tmp_len);
+ goto again;
+ }
+ assert(header->magic == EPOLL_USERPOLL_HEADER_MAGIC);
+
+ index = mmap(NULL, header->index_length, PROT_WRITE|PROT_READ,
+ MAP_SHARED, epfd, header->header_length);
+ if (index == MAP_FAILED)
+ ksft_exit_fail_msg("Failed map(index)\n");
+
+ *_header = header;
+ *_index = index;
+}
+
+static void uepoll_munmap(struct epoll_uheader *header,
+ unsigned int *index)
+{
+ int rc;
+
+ rc = munmap(index, header->index_length);
+ if (rc)
+ ksft_exit_fail_msg("Failed munmap(index)\n");
+
+ rc = munmap(header, header->header_length);
+ if (rc)
+ ksft_exit_fail_msg("Failed munmap(header)\n");
+}
+
+static int do_bench(struct cpu_map *cpu, unsigned int nthreads)
+{
+ struct epoll_event ev, events[nthreads];
+ struct thread_ctx threads[nthreads];
+ pthread_attr_t thrattr;
+ struct thread_ctx *ctx;
+ int rc, epfd, nfds;
+ cpu_set_t cpuset;
+ unsigned int i;
+
+ struct epoll_uheader *header;
+ unsigned int *index;
+
+ unsigned long long epoll_calls = 0, epoll_nsecs;
+ unsigned long long ucnt, ucnt_sum = 0, eagains = 0;
+
+ thr_ready = 0;
+ start = 0;
+
+ epfd = epoll_create2(EPOLL_USERPOLL, nthreads);
+ if (epfd < 0)
+ ksft_exit_fail_msg("Failed epoll_create2()\n");
+
+ for (i = 0; i < nthreads; i++) {
+ ctx = &threads[i];
+
+ ctx->efd = eventfd(0, EFD_NONBLOCK);
+ if (ctx->efd < 0)
+ ksft_exit_fail_msg("Failed eventfd()\n");
+
+ ev.events = EPOLLIN | EPOLLET;
+ ev.data = (uintptr_t) ctx;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, ctx->efd, &ev);
+ if (rc)
+ ksft_exit_fail_msg("Failed epoll_ctl()\n");
+
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu->map[i % cpu->nr], &cpuset);
+
+ pthread_attr_init(&thrattr);
+ rc = pthread_attr_setaffinity_np(&thrattr, sizeof(cpu_set_t),
+ &cpuset);
+ if (rc) {
+ errno = rc;
+ ksft_exit_fail_msg("Failed pthread_attr_setaffinity_np()\n");
+ }
+
+ rc = pthread_create(&ctx->thread, NULL, thread_work, ctx);
+ if (rc) {
+ errno = rc;
+ ksft_exit_fail_msg("Failed pthread_create()\n");
+ }
+ }
+
+ /* Mmap all pointers */
+ uepoll_mmap(epfd, &header, &index);
+
+ while (thr_ready != nthreads)
+ ;
+
+ /* Signal start for all threads */
+ start = 1;
+
+ epoll_nsecs = nsecs();
+ while (1) {
+ nfds = uepoll_wait(header, index, epfd, events, nthreads);
+ if (nfds < 0)
+ ksft_exit_fail_msg("Failed uepoll_wait()\n");
+
+ epoll_calls++;
+
+ for (i = 0; i < (unsigned int)nfds; ++i) {
+ ctx = (void *)(uintptr_t) events[i].data;
+ rc = read(ctx->efd, &ucnt, sizeof(ucnt));
+ if (rc < 0) {
+ assert(errno == EAGAIN);
+ continue;
+ }
+ assert(rc == sizeof(ucnt));
+ ucnt_sum += ucnt;
+ if (ucnt_sum == nthreads * ITERS)
+ goto end;
+ }
+ }
+end:
+ epoll_nsecs = nsecs() - epoll_nsecs;
+
+ for (i = 0; i < nthreads; i++) {
+ ctx = &threads[i];
+ pthread_join(ctx->thread, NULL);
+ }
+ uepoll_munmap(header, index);
+ close(epfd);
+
+ ksft_print_msg("%7d %8lld %8lld\n",
+ nthreads,
+ ITERS*nthreads/(epoll_nsecs/1000/1000),
+ epoll_nsecs/1000/1000);
+
+ return 0;
+}
+
+/**
+ * uepoll loop
+ */
+TEST(uepoll_basics)
+{
+ unsigned int i, nthreads_arr[] = {8, 16, 32, 64};
+ struct cpu_map *cpu;
+
+ cpu = cpu_map__new();
+ if (!cpu) {
+ errno = ENOMEM;
+ ksft_exit_fail_msg("Failed cpu_map__new()\n");
+ }
+
+ ksft_print_msg("threads events/ms run-time ms\n");
+ for (i = 0; i < ARRAY_SIZE(nthreads_arr); i++)
+ do_bench(cpu, nthreads_arr[i]);
+
+ cpu_map__put(cpu);
+}
+
+/**
+ * Checks different flags and args
+ */
+TEST(uepoll_args)
+{
+ struct epoll_event ev;
+ int epfd, evfd, rc;
+
+ /* Fail */
+ epfd = epoll_create2(EPOLL_USERPOLL, (1<<16)+1);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(epfd, -1);
+
+ /* Fail */
+ epfd = epoll_create2(EPOLL_USERPOLL, 0);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(epfd, -1);
+
+ /* Success */
+ epfd = epoll_create2(EPOLL_USERPOLL, (1<<16));
+ ASSERT_GE(epfd, 0);
+
+ /* Success */
+ evfd = eventfd(0, EFD_NONBLOCK);
+ ASSERT_GE(evfd, 0);
+
+ /* Fail, expect EPOLLET */
+ ev.events = EPOLLIN;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, evfd, &ev);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(rc, -1);
+
+ /* Fail, no support for EPOLLEXCLUSIVE */
+ ev.events = EPOLLIN | EPOLLET | EPOLLEXCLUSIVE;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, evfd, &ev);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(rc, -1);
+
+ /* Success */
+ ev.events = EPOLLIN | EPOLLET;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, evfd, &ev);
+ ASSERT_EQ(rc, 0);
+
+ /* Fail, expect events and maxevents as zeroes */
+ rc = epoll_wait(epfd, &ev, 1, -1);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(rc, -1);
+
+ /* Fail, expect events as zero */
+ rc = epoll_wait(epfd, &ev, 0, -1);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(rc, -1);
+
+ /* Fail, expect maxevents as zero */
+ rc = epoll_wait(epfd, NULL, 1, -1);
+ ASSERT_EQ(errno, EINVAL);
+ ASSERT_EQ(rc, -1);
+
+ /* Success */
+ rc = epoll_wait(epfd, NULL, 0, 0);
+ ASSERT_EQ(rc, 0);
+
+ close(epfd);
+ close(evfd);
+}
+
+static void *signal_eventfd_work(void *arg)
+{
+ unsigned long long cnt;
+
+ int rc, evfd = *(int *)arg;
+
+ sleep(1);
+ cnt = 1;
+ rc = write(evfd, &cnt, sizeof(cnt));
+ assert(rc == 8);
+
+ return NULL;
+}
+
+/**
+ * Nested poll
+ */
+TEST(uepoll_poll)
+{
+ int epfd, uepfd, evfd, rc;
+
+ struct epoll_event ev;
+ pthread_t thread;
+
+ /* Success */
+ uepfd = epoll_create2(EPOLL_USERPOLL, 128);
+ ASSERT_GE(uepfd, 0);
+
+ /* Success */
+ epfd = epoll_create2(0, 0);
+ ASSERT_GE(epfd, 0);
+
+ /* Success */
+ evfd = eventfd(0, EFD_NONBLOCK);
+ ASSERT_GE(evfd, 0);
+
+ /* Success */
+ ev.events = EPOLLIN | EPOLLET;
+ rc = epoll_ctl(uepfd, EPOLL_CTL_ADD, evfd, &ev);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ ev.events = EPOLLIN | EPOLLET;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, uepfd, &ev);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = epoll_wait(epfd, &ev, 1, 0);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = pthread_create(&thread, NULL, signal_eventfd_work, &evfd);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = epoll_wait(epfd, &ev, 1, 5000);
+ ASSERT_EQ(rc, 1);
+
+ close(uepfd);
+ close(epfd);
+ close(evfd);
+}
+
+/**
+ * One shot
+ */
+TEST(uepoll_epolloneshot)
+{
+ int epfd, evfd, rc;
+ unsigned long long cnt;
+
+ struct epoll_uheader *header;
+ unsigned int *index;
+
+ struct epoll_event ev;
+ pthread_t thread;
+
+ /* Success */
+ epfd = epoll_create2(EPOLL_USERPOLL, 128);
+ ASSERT_GE(epfd, 0);
+
+ /* Mmap all pointers */
+ uepoll_mmap(epfd, &header, &index);
+
+ /* Success */
+ evfd = eventfd(0, EFD_NONBLOCK);
+ ASSERT_GE(evfd, 0);
+
+ /* Success */
+ ev.events = EPOLLIN | EPOLLET | EPOLLONESHOT;
+ rc = epoll_ctl(epfd, EPOLL_CTL_ADD, evfd, &ev);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = pthread_create(&thread, NULL, signal_eventfd_work, &evfd);
+ ASSERT_EQ(rc, 0);
+
+ /* Fail, expect -ESTALE */
+ rc = epoll_wait(epfd, NULL, 0, 3000);
+ ASSERT_EQ(errno, ESTALE);
+ ASSERT_EQ(rc, -1);
+
+ /* Success */
+ rc = uepoll_wait(header, index, epfd, &ev, 1);
+ ASSERT_EQ(rc, 1);
+
+ /* Success */
+ rc = pthread_create(&thread, NULL, signal_eventfd_work, &evfd);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = epoll_wait(epfd, NULL, 0, 3000);
+ ASSERT_EQ(rc, 0);
+
+
+ /* Success */
+ ev.events = EPOLLIN | EPOLLET;
+ rc = epoll_ctl(epfd, EPOLL_CTL_MOD, evfd, &ev);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = pthread_create(&thread, NULL, signal_eventfd_work, &evfd);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = uepoll_wait(header, index, epfd, &ev, 1);
+ ASSERT_EQ(rc, 1);
+
+ /* Success */
+ rc = pthread_create(&thread, NULL, signal_eventfd_work, &evfd);
+ ASSERT_EQ(rc, 0);
+
+ /* Success */
+ rc = uepoll_wait(header, index, epfd, &ev, 1);
+ ASSERT_EQ(rc, 1);
+
+ uepoll_munmap(header, index);
+ close(epfd);
+ close(evfd);
+}
+
+TEST_HARNESS_MAIN
--
2.21.0
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