Gh0st
/
linux
mirror of https://github.com/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

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 <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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
include/linux/rcupdate.h
View File

@ -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

14
include/linux/rhashtable.h
View File

@ -272,13 +272,13 @@ struct rhash_lock_head __rcu **rht_bucket_nested_insert(
rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
#define rht_dereference_rcu(p, ht) \
rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
rcu_dereference_all_check(p, lockdep_rht_mutex_is_held(ht))
#define rht_dereference_bucket(p, tbl, hash) \
rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
#define rht_dereference_bucket_rcu(p, tbl, hash) \
rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash))
rcu_dereference_all_check(p, lockdep_rht_bucket_is_held(tbl, hash))
#define rht_entry(tpos, pos, member) \
({ tpos = container_of(pos, typeof(*tpos), member); 1; })
@ -373,7 +373,7 @@ static inline struct rhash_head *__rht_ptr(
static inline struct rhash_head *rht_ptr_rcu(
struct rhash_lock_head __rcu *const *bkt)
{
return __rht_ptr(rcu_dereference(*bkt), bkt);
return __rht_ptr(rcu_dereference_all(*bkt), bkt);
}
static inline struct rhash_head *rht_ptr(
@ -497,7 +497,7 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
for (({barrier(); }), \
pos = head; \
!rht_is_a_nulls(pos); \
pos = rcu_dereference_raw(pos->next))
pos = rcu_dereference_all(pos->next))
/**
* rht_for_each_rcu - iterate over rcu hash chain
@ -513,7 +513,7 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
for (({barrier(); }), \
pos = rht_ptr_rcu(rht_bucket(tbl, hash)); \
!rht_is_a_nulls(pos); \
pos = rcu_dereference_raw(pos->next))
pos = rcu_dereference_all(pos->next))
/**
* rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
@ -560,7 +560,7 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
* list returned by rhltable_lookup.
*/
#define rhl_for_each_rcu(pos, list) \
for (pos = list; pos; pos = rcu_dereference_raw(pos->next))
for (pos = list; pos; pos = rcu_dereference_all(pos->next))
/**
* rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
@ -574,7 +574,7 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
*/
#define rhl_for_each_entry_rcu(tpos, pos, list, member) \
for (pos = list; pos && rht_entry(tpos, pos, member); \
pos = rcu_dereference_raw(pos->next))
pos = rcu_dereference_all(pos->next))
static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
const void *obj)