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SubjectRe: [rcu:rcu/dev 39/39] kernel/rcu/tree_exp.h:163:9: sparse: incorrect type in argument 1 (different modifiers)
On Fri, Mar 09, 2018 at 05:41:27AM +0800, kbuild test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/dev
> head: b8909ec707bb5beba94e7c7d62cc6b3115ceae50
> commit: b8909ec707bb5beba94e7c7d62cc6b3115ceae50 [39/39] rcu: Protect all sync_rcu_preempt_exp_done() with rcu_node lock
> reproduce:
> # apt-get install sparse
> git checkout b8909ec707bb5beba94e7c7d62cc6b3115ceae50
> make ARCH=x86_64 allmodconfig
> make C=1 CF=-D__CHECK_ENDIAN__
>
>
> sparse warnings: (new ones prefixed by >>)
>
[...]
> kernel/rcu/tree.c:345:6: sparse: symbol 'rcu_dynticks_curr_cpu_in_eqs' was not declared. Should it be static?
> kernel/rcu/tree.c:3953:21: sparse: incorrect type in argument 1 (different modifiers) @@ expected int ( *threadfn )( ... ) @@ got int ( [noreint ( *threadfn )( ... ) @@
> kernel/rcu/tree.c:3953:21: expected int ( *threadfn )( ... )
> kernel/rcu/tree.c:3953:21: got int ( [noreturn] *<noident> )( ... )
> >> kernel/rcu/tree_exp.h:163:9: sparse: incorrect type in argument 1 (different modifiers) @@ expected struct lockdep_map const *lock @@ got strustruct lockdep_map const *lock @@
> kernel/rcu/tree_exp.h:163:9: expected struct lockdep_map const *lock
> kernel/rcu/tree_exp.h:163:9: got struct lockdep_map [noderef] *<noident>
> kernel/rcu/tree.c:1752:9: sparse: context imbalance in 'rcu_start_future_gp' - different lock contexts for basic block
> kernel/rcu/tree.c:2786:9: sparse: context imbalance in 'force_qs_rnp' - different lock contexts for basic block
> kernel/rcu/tree.c:2849:25: sparse: context imbalance in 'force_quiescent_state' - unexpected unlock
> kernel/rcu/tree_exp.h:203:9: sparse: too many warnings
>
> vim +163 kernel/rcu/tree_exp.h
>
> 151
> 152 /*
> 153 * Return non-zero if there is no RCU expedited grace period in progress
> 154 * for the specified rcu_node structure, in other words, if all CPUs and
> 155 * tasks covered by the specified rcu_node structure have done their bit
> 156 * for the current expedited grace period. Works only for preemptible
> 157 * RCU -- other RCU implementation use other means.
> 158 *
> 159 * Caller must hold the specificed rcu_node structure's ->lock
> 160 */
> 161 static bool sync_rcu_preempt_exp_done(struct rcu_node *rnp)
> 162 {
> > 163 lockdep_assert_held(&rnp->lock);

OK, so we need ACCESS_PRIVATE() to visit ->lock in rcu_node. I will
introduce something like:

#define rcu_node_lock_assert_held(rnp) lockdep_assert_held(&ACCESS_PRIVATE(rnp, lock))

in v3.

Regards,
Boqun
> 164
> 165 return rnp->exp_tasks == NULL &&
> 166 READ_ONCE(rnp->expmask) == 0;
> 167 }
> 168
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
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