| Message ID | 20200324153643.15527-3-will@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Improve list integrity checking | expand |
On Tue, Mar 24, 2020 at 03:36:24PM +0000, Will Deacon wrote: > Commit 02b99b38f3d9 ("rcu: Add a hlist_nulls_unhashed_lockless() function") > introduced the (as yet unused) hlist_nulls_unhashed_lockless() function > to avoid KCSAN reports when an RCU reader checks the 'hashed' status > of an 'hlist_nulls' concurrently undergoing modification. > > Remove the unused function and add a READ_ONCE() to hlist_nulls_unhashed(), > just like we do already for hlist_nulls_empty(). > > Cc: Paul E. McKenney <paulmck@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Will Deacon <will@kernel.org> > --- > include/linux/list_nulls.h | 14 -------------- > 1 file changed, 14 deletions(-) Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On Tue, Mar 24, 2020 at 03:36:24PM +0000, Will Deacon wrote: > Commit 02b99b38f3d9 ("rcu: Add a hlist_nulls_unhashed_lockless() function") > introduced the (as yet unused) hlist_nulls_unhashed_lockless() function > to avoid KCSAN reports when an RCU reader checks the 'hashed' status > of an 'hlist_nulls' concurrently undergoing modification. > > Remove the unused function and add a READ_ONCE() to hlist_nulls_unhashed(), > just like we do already for hlist_nulls_empty(). > > Cc: Paul E. McKenney <paulmck@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Will Deacon <will@kernel.org> Well, I guess that the added docbook comment might be seen as worthwhile. Acked-by: Paul E. McKenney <paulmck@kernel.org> > --- > include/linux/list_nulls.h | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h > index fa6e8471bd22..3a9ff01e9a11 100644 > --- a/include/linux/list_nulls.h > +++ b/include/linux/list_nulls.h > @@ -65,20 +65,6 @@ static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr) > * but hlist_nulls_del() does not. > */ > static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h) > -{ > - return !h->pprev; > -} > - > -/** > - * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized? > - * @h: Node to be checked > - * > - * Not that not all removal functions will leave a node in unhashed state. > - * For example, hlist_del_init_rcu() leaves the node in unhashed state, > - * but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this > - * function may be used locklessly. > - */ > -static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h) > { > return !READ_ONCE(h->pprev); > } > -- > 2.20.1 >
diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h index fa6e8471bd22..3a9ff01e9a11 100644 --- a/include/linux/list_nulls.h +++ b/include/linux/list_nulls.h @@ -65,20 +65,6 @@ static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr) * but hlist_nulls_del() does not. */ static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h) -{ - return !h->pprev; -} - -/** - * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized? - * @h: Node to be checked - * - * Not that not all removal functions will leave a node in unhashed state. - * For example, hlist_del_init_rcu() leaves the node in unhashed state, - * but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this - * function may be used locklessly. - */ -static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h) { return !READ_ONCE(h->pprev); }
Commit 02b99b38f3d9 ("rcu: Add a hlist_nulls_unhashed_lockless() function") introduced the (as yet unused) hlist_nulls_unhashed_lockless() function to avoid KCSAN reports when an RCU reader checks the 'hashed' status of an 'hlist_nulls' concurrently undergoing modification. Remove the unused function and add a READ_ONCE() to hlist_nulls_unhashed(), just like we do already for hlist_nulls_empty(). Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Will Deacon <will@kernel.org> --- include/linux/list_nulls.h | 14 -------------- 1 file changed, 14 deletions(-)