From 2669dde7a8c67e3efe8052d75d6040de2cbb5e5a Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Wed, 11 Feb 2026 10:57:47 -0800 Subject: selftests/bpf: Fix map_kptr grace period wait Commit c27cea4416a3 ("rcu: Re-implement RCU Tasks Trace in terms of SRCU-fast") broke map_kptr selftest since it removed the function we were kprobing. Use a new kfunc that invokes call_rcu_tasks_trace and sets a program provided pointer to an integer to 1. Technically this can be unsafe if the memory being written to from the callback disappears, but this is just for usage in a test where we ensure we spin until we see the value to be set to 1, so it's ok. Reported-by: Shung-Hsi Yu Fixes: c27cea4416a3 ("rcu: Re-implement RCU Tasks Trace in terms of SRCU-fast") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260211185747.3630539-1-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- .../testing/selftests/bpf/test_kmods/bpf_testmod.c | 28 ++++++++++++++++++++++ .../selftests/bpf/test_kmods/bpf_testmod_kfunc.h | 1 + 2 files changed, 29 insertions(+) (limited to 'tools/testing/selftests/bpf/test_kmods') diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c index 186a25ab429a..e62c6b78657f 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include "bpf_testmod.h" @@ -885,6 +886,32 @@ __bpf_kfunc void bpf_kfunc_call_test_sleepable(void) { } +struct bpf_kfunc_rcu_tasks_trace_data { + struct rcu_head rcu; + int *done; +}; + +static void bpf_kfunc_rcu_tasks_trace_cb(struct rcu_head *rhp) +{ + struct bpf_kfunc_rcu_tasks_trace_data *data; + + data = container_of(rhp, struct bpf_kfunc_rcu_tasks_trace_data, rcu); + WRITE_ONCE(*data->done, 1); + kfree(data); +} + +__bpf_kfunc int bpf_kfunc_call_test_call_rcu_tasks_trace(int *done) +{ + struct bpf_kfunc_rcu_tasks_trace_data *data; + + data = kmalloc(sizeof(*data), GFP_ATOMIC); + if (!data) + return -ENOMEM; + data->done = done; + call_rcu_tasks_trace(&data->rcu, bpf_kfunc_rcu_tasks_trace_cb); + return 0; +} + __bpf_kfunc int bpf_kfunc_init_sock(struct init_sock_args *args) { int proto; @@ -1222,6 +1249,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE) BTF_ID_FLAGS(func, bpf_kfunc_call_test_static_unused_arg) BTF_ID_FLAGS(func, bpf_kfunc_call_test_offset) BTF_ID_FLAGS(func, bpf_kfunc_call_test_sleepable, KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_kfunc_call_test_call_rcu_tasks_trace) BTF_ID_FLAGS(func, bpf_kfunc_init_sock, KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_kfunc_close_sock, KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_connect, KF_SLEEPABLE) diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h index d5c5454e257e..b393bf771131 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h @@ -118,6 +118,7 @@ void bpf_kfunc_call_test_mem_len_fail2(__u64 *mem, int len) __ksym; void bpf_kfunc_call_test_destructive(void) __ksym; void bpf_kfunc_call_test_sleepable(void) __ksym; +int bpf_kfunc_call_test_call_rcu_tasks_trace(int *done) __ksym; void bpf_kfunc_call_test_offset(struct prog_test_ref_kfunc *p); struct prog_test_member *bpf_kfunc_call_memb_acquire(void); -- cgit v1.2.3