[PATCH 5.10 63/65] bpf: Consolidate shared test timing code

Greg Kroah-Hartman
2022-08-01T11:58:33Z

From: Tianchen Ding <dtcccc@linux.alibaba.com>

From: Lorenz Bauer <lmb@cloudflare.com>

commit 607b9cc92bd7208338d714a22b8082fe83bcb177 upstream.

Share the timing / signal interruption logic between different
implementations of PROG_TEST_RUN. There is a change in behaviour
as well. We check the loop exit condition before checking for
pending signals. This resolves an edge case where a signal
arrives during the last iteration. Instead of aborting with
EINTR we return the successful result to user space.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-2-lmb@cloudflare.com
[dtcccc: fix conflicts in bpf_test_run()]
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bpf/test_run.c | 140 +++++++++++++++++++++++++++++------------------------
1 file changed, 78 insertions(+), 62 deletions(-)

--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -16,14 +16,78 @@
#define CREATE_TRACE_POINTS
#include <trace/events/bpf_test_run.h>

+struct bpf_test_timer {
+ enum { NO_PREEMPT, NO_MIGRATE } mode;
+ u32 i;
+ u64 time_start, time_spent;
+};
+
+static void bpf_test_timer_enter(struct bpf_test_timer *t)
+ __acquires(rcu)
+{
+ rcu_read_lock();
+ if (t->mode == NO_PREEMPT)
+ preempt_disable();
+ else
+ migrate_disable();
+
+ t->time_start = ktime_get_ns();
+}
+
+static void bpf_test_timer_leave(struct bpf_test_timer *t)
+ __releases(rcu)
+{
+ t->time_start = 0;
+
+ if (t->mode == NO_PREEMPT)
+ preempt_enable();
+ else
+ migrate_enable();
+ rcu_read_unlock();
+}
+
+static bool bpf_test_timer_continue(struct bpf_test_timer *t, u32 repeat, int *err, u32 *duration)
+ __must_hold(rcu)
+{
+ t->i++;
+ if (t->i >= repeat) {
+ /* We're done. */
+ t->time_spent += ktime_get_ns() - t->time_start;
+ do_div(t->time_spent, t->i);
+ *duration = t->time_spent > U32_MAX ? U32_MAX : (u32)t->time_spent;
+ *err = 0;
+ goto reset;
+ }
+
+ if (signal_pending(current)) {
+ /* During iteration: we've been cancelled, abort. */
+ *err = -EINTR;
+ goto reset;
+ }
+
+ if (need_resched()) {
+ /* During iteration: we need to reschedule between runs. */
+ t->time_spent += ktime_get_ns() - t->time_start;
+ bpf_test_timer_leave(t);
+ cond_resched();
+ bpf_test_timer_enter(t);
+ }
+
+ /* Do another round. */
+ return true;
+
+reset:
+ t->i = 0;
+ return false;
+}
+
static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
u32 *retval, u32 *time, bool xdp)
{
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = { NULL };
+ struct bpf_test_timer t = { NO_MIGRATE };
enum bpf_cgroup_storage_type stype;
- u64 time_start, time_spent = 0;
- int ret = 0;
- u32 i;
+ int ret;

for_each_cgroup_storage_type(stype) {
storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
@@ -38,10 +102,8 @@ static int bpf_test_run(struct bpf_prog
if (!repeat)
repeat = 1;

- rcu_read_lock();
- migrate_disable();
- time_start = ktime_get_ns();
- for (i = 0; i < repeat; i++) {
+ bpf_test_timer_enter(&t);
+ do {
ret = bpf_cgroup_storage_set(storage);
if (ret)
break;
@@ -53,29 +115,8 @@ static int bpf_test_run(struct bpf_prog

bpf_cgroup_storage_unset();

- if (signal_pending(current)) {
- ret = -EINTR;
- break;
- }
-
- if (need_resched()) {
- time_spent += ktime_get_ns() - time_start;
- migrate_enable();
- rcu_read_unlock();
-
- cond_resched();
-
- rcu_read_lock();
- migrate_disable();
- time_start = ktime_get_ns();
- }
- }
- time_spent += ktime_get_ns() - time_start;
- migrate_enable();
- rcu_read_unlock();
-
- do_div(time_spent, repeat);
- *time = time_spent > U32_MAX ? U32_MAX : (u32)time_spent;
+ } while (bpf_test_timer_continue(&t, repeat, &ret, time));
+ bpf_test_timer_leave(&t);

for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
@@ -688,18 +729,17 @@ int bpf_prog_test_run_flow_dissector(str
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
+ struct bpf_test_timer t = { NO_PREEMPT };
u32 size = kattr->test.data_size_in;
struct bpf_flow_dissector ctx = {};
u32 repeat = kattr->test.repeat;
struct bpf_flow_keys *user_ctx;
struct bpf_flow_keys flow_keys;
- u64 time_start, time_spent = 0;
const struct ethhdr *eth;
unsigned int flags = 0;
u32 retval, duration;
void *data;
int ret;
- u32 i;

if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
return -EINVAL;
@@ -735,39 +775,15 @@ int bpf_prog_test_run_flow_dissector(str
ctx.data = data;
ctx.data_end = (__u8 *)data + size;

- rcu_read_lock();
- preempt_disable();
- time_start = ktime_get_ns();
- for (i = 0; i < repeat; i++) {
+ bpf_test_timer_enter(&t);
+ do {
retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
size, flags);
+ } while (bpf_test_timer_continue(&t, repeat, &ret, &duration));
+ bpf_test_timer_leave(&t);

- if (signal_pending(current)) {
- preempt_enable();
- rcu_read_unlock();
-
- ret = -EINTR;
- goto out;
- }
-
- if (need_resched()) {
- time_spent += ktime_get_ns() - time_start;
- preempt_enable();
- rcu_read_unlock();
-
- cond_resched();
-
- rcu_read_lock();
- preempt_disable();
- time_start = ktime_get_ns();
- }
- }
- time_spent += ktime_get_ns() - time_start;
- preempt_enable();
- rcu_read_unlock();
-
- do_div(time_spent, repeat);
- duration = time_spent > U32_MAX ? U32_MAX : (u32)time_spent;
+ if (ret < 0)
+ goto out;

ret = bpf_test_finish(kattr, uattr, &flow_keys, sizeof(flow_keys),
retval, duration);