| Message ID | 20191010061916.198761-2-songliubraving@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf/stackmap: fix A-A deadlock in bpf_get_stack() | expand |
diff --git a/include/linux/sched.h b/include/linux/sched.h index 2c2e56bd8913..fb0fcbd1b6f6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1995,4 +1995,5 @@ int sched_trace_rq_cpu(struct rq *rq); const struct cpumask *sched_trace_rd_span(struct root_domain *rd); +bool this_rq_is_locked(void); #endif diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7880f4f64d0e..577cbe7c05fc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -138,6 +138,14 @@ struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) } } +bool this_rq_is_locked(void) +{ + struct rq *rq; + + rq = this_rq(); + return raw_spin_is_locked(&rq->lock); +} + /* * RQ-clock updating methods: */
this_rq_is_locked() is introduced to check whether current CPU is holding rq_lock(). This will be used in bpf/stackmap.c to decide whether is safe to call up_read(), which may call rq_lock() for the same CPU. Fixes: commit 615755a77b24 ("bpf: extend stackmap to save binary_build_id+offset instead of address") Cc: stable@vger.kernel.org # v4.17+ Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Song Liu <songliubraving@fb.com> --- include/linux/sched.h | 1 + kernel/sched/core.c | 8 ++++++++ 2 files changed, 9 insertions(+) -- 2.17.1