From bee8a520eb84950193d0566ea2c2e46406a4b6ce Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 9 Sep 2025 17:50:56 +0800 Subject: rhashtable: Use rcu_dereference_all and rcu_dereference_all_check Add rcu_dereference_all and rcu_dereference_all_check so that library code such as rhashtable can be used with any RCU variant. As it stands rcu_dereference is used within rashtable, which creates false-positive warnings if the user calls it from another RCU context, such as preempt_disable(). Use the rcu_dereference_all and rcu_dereference_all_check calls in rhashtable to suppress these warnings. Also replace the rcu_dereference_raw calls in the list iterators with rcu_dereference_all to uncover buggy calls. Reported-by: Menglong Dong Signed-off-by: Herbert Xu Reviewed-by: Paul E. McKenney Signed-off-by: Herbert Xu --- include/linux/rcupdate.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include/linux/rcupdate.h') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 120536f4c6eb..448eb1f0cb48 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -713,6 +713,24 @@ do { \ (c) || rcu_read_lock_sched_held(), \ __rcu) +/** + * rcu_dereference_all_check() - rcu_dereference_all with debug checking + * @p: The pointer to read, prior to dereferencing + * @c: The conditions under which the dereference will take place + * + * This is similar to rcu_dereference_check(), but allows protection + * by all forms of vanilla RCU readers, including preemption disabled, + * bh-disabled, and interrupt-disabled regions of code. Note that "vanilla + * RCU" excludes SRCU and the various Tasks RCU flavors. Please note + * that this macro should not be backported to any Linux-kernel version + * preceding v5.0 due to changes in synchronize_rcu() semantics prior + * to that version. + */ +#define rcu_dereference_all_check(p, c) \ + __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ + (c) || rcu_read_lock_any_held(), \ + __rcu) + /* * The tracing infrastructure traces RCU (we want that), but unfortunately * some of the RCU checks causes tracing to lock up the system. @@ -767,6 +785,14 @@ do { \ */ #define rcu_dereference_sched(p) rcu_dereference_sched_check(p, 0) +/** + * rcu_dereference_all() - fetch RCU-all-protected pointer for dereferencing + * @p: The pointer to read, prior to dereferencing + * + * Makes rcu_dereference_check() do the dirty work. + */ +#define rcu_dereference_all(p) rcu_dereference_all_check(p, 0) + /** * rcu_pointer_handoff() - Hand off a pointer from RCU to other mechanism * @p: The pointer to hand off -- cgit v1.2.3