migrate_disable() and rcu_read_lock() are used to together in many case in bpf. However, when PREEMPT_RCU is not enabled, rcu_read_lock() will disable preemption, which indicate migrate_disable(), so we don't need to call it in this case.
In this series, we introduce rcu_read_lock_dont_migrate and rcu_read_unlock_migrate, which will call migrate_disable and migrate_enable only when PREEMPT_RCU enabled. And use rcu_read_lock_dont_migrate in bpf subsystem. Changes since V2: * make rcu_read_lock_dont_migrate() more compatible by using IS_ENABLED() Changes since V1: * introduce rcu_read_lock_dont_migrate() instead of rcu_migrate_disable() + rcu_read_lock() Menglong Dong (7): rcu: add rcu_read_lock_dont_migrate() bpf: use rcu_read_lock_dont_migrate() for bpf_cgrp_storage_free() bpf: use rcu_read_lock_dont_migrate() for bpf_inode_storage_free() bpf: use rcu_read_lock_dont_migrate() for bpf_iter_run_prog() bpf: use rcu_read_lock_dont_migrate() for bpf_task_storage_free() bpf: use rcu_read_lock_dont_migrate() for bpf_prog_run_array_cg() bpf: use rcu_read_lock_dont_migrate() for trampoline.c include/linux/rcupdate.h | 14 ++++++++++++++ kernel/bpf/bpf_cgrp_storage.c | 6 ++---- kernel/bpf/bpf_inode_storage.c | 6 ++---- kernel/bpf/bpf_iter.c | 6 ++---- kernel/bpf/bpf_task_storage.c | 6 ++---- kernel/bpf/cgroup.c | 6 ++---- kernel/bpf/trampoline.c | 18 ++++++------------ 7 files changed, 30 insertions(+), 32 deletions(-) -- 2.50.1
