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rhashtable: Use rcu_dereference_all and rcu_dereference_all_check

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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 <dongml2@chinatelecom.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu
2025-09-09 17:50:56 +08:00
parent f75f66683d
commit bee8a520eb
2 changed files with 33 additions and 7 deletions
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26
include/linux/rcupdate.h
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@@ -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