From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>,
"Martin KaFai Lau" <martin.lau@kernel.org>
Subject: [PATCH bpf-next v2 2/3] selftests/bpf: Fix rcu_read_lock test with new MEM_RCU semantics
Date: Sat, 3 Dec 2022 10:46:07 -0800 [thread overview]
Message-ID: <20221203184607.478314-1-yhs@fb.com> (raw)
In-Reply-To: <20221203184557.476871-1-yhs@fb.com>
Add MEM_RCU pointer null checking for related tests. Also
modified task_acquire test so it takes a rcu ptr 'ptr' where
'ptr = rcu_ptr->rcu_field'.
Signed-off-by: Yonghong Song <yhs@fb.com>
---
.../selftests/bpf/progs/rcu_read_lock.c | 55 +++++++++++++++----
1 file changed, 45 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
index 94a970076b98..cf06a34fcb02 100644
--- a/tools/testing/selftests/bpf/progs/rcu_read_lock.c
+++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
@@ -23,13 +23,14 @@ struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
void bpf_key_put(struct bpf_key *key) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
-struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
+struct task_struct *bpf_task_acquire_not_zero(struct task_struct *p) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int get_cgroup_id(void *ctx)
{
struct task_struct *task;
+ struct css_set *cgroups;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
@@ -37,7 +38,11 @@ int get_cgroup_id(void *ctx)
/* simulate bpf_get_current_cgroup_id() helper */
bpf_rcu_read_lock();
- cgroup_id = task->cgroups->dfl_cgrp->kn->id;
+ cgroups = task->cgroups;
+ if (!cgroups)
+ goto unlock;
+ cgroup_id = cgroups->dfl_cgrp->kn->id;
+unlock:
bpf_rcu_read_unlock();
return 0;
}
@@ -56,6 +61,8 @@ int task_succ(void *ctx)
bpf_rcu_read_lock();
/* region including helper using rcu ptr real_parent */
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!ptr)
@@ -92,7 +99,10 @@ int two_regions(void *ctx)
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
bpf_rcu_read_unlock();
return 0;
}
@@ -105,7 +115,10 @@ int non_sleepable_1(void *ctx)
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
bpf_rcu_read_unlock();
return 0;
}
@@ -121,7 +134,10 @@ int non_sleepable_2(void *ctx)
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
bpf_rcu_read_unlock();
return 0;
}
@@ -129,16 +145,28 @@ int non_sleepable_2(void *ctx)
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int task_acquire(void *ctx)
{
- struct task_struct *task, *real_parent;
+ struct task_struct *task, *real_parent, *gparent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
+
+ /* rcu_ptr->rcu_field */
+ gparent = real_parent->real_parent;
+ if (!gparent)
+ goto out;
+
/* acquire a reference which can be used outside rcu read lock region */
- real_parent = bpf_task_acquire(real_parent);
+ gparent = bpf_task_acquire_not_zero(gparent);
+ if (!gparent)
+ goto out;
+
+ (void)bpf_task_storage_get(&map_a, gparent, 0, 0);
+ bpf_task_release(gparent);
+out:
bpf_rcu_read_unlock();
- (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
- bpf_task_release(real_parent);
return 0;
}
@@ -181,9 +209,12 @@ int non_sleepable_rcu_mismatch(void *ctx)
/* non-sleepable: missing bpf_rcu_read_unlock() in one path */
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
if (real_parent)
bpf_rcu_read_unlock();
+out:
return 0;
}
@@ -199,16 +230,17 @@ int inproper_sleepable_helper(void *ctx)
/* sleepable helper in rcu read lock region */
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
- if (!regs) {
- bpf_rcu_read_unlock();
- return 0;
- }
+ if (!regs)
+ goto out;
ptr = (void *)PT_REGS_IP(regs);
(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
user_data = value;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
bpf_rcu_read_unlock();
return 0;
}
@@ -239,7 +271,10 @@ int nested_rcu_region(void *ctx)
bpf_rcu_read_lock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
+ if (!real_parent)
+ goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
bpf_rcu_read_unlock();
bpf_rcu_read_unlock();
return 0;
--
2.30.2
next prev parent reply other threads:[~2022-12-03 18:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-03 18:45 [PATCH bpf-next v2 0/3] bpf: Handle MEM_RCU type properly Yonghong Song
2022-12-03 18:46 ` [PATCH bpf-next v2 1/3] " Yonghong Song
2022-12-03 18:46 ` Yonghong Song [this message]
2022-12-03 18:46 ` [PATCH bpf-next v2 3/3] docs/bpf: Add KF_RCU documentation Yonghong Song
2022-12-04 21:00 ` [PATCH bpf-next v2 0/3] bpf: Handle MEM_RCU type properly patchwork-bot+netdevbpf
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