On Thu, Mar 08, 2018 at 04:34:43PM -0800, Paul E. McKenney wrote: > On Fri, Mar 09, 2018 at 06:52:34AM +0800, Boqun Feng wrote: > > 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. > > Or use this, which is in kernel/rcu/rcu.h: > > #define raw_lockdep_assert_held_rcu_node(p) \ > lockdep_assert_held(&ACCESS_PRIVATE(p, lock)) >
Good point, thank you for pointing this out ;-) Regards, Boqun > Thanx, Paul >
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