| Message ID | 20200324153643.15527-6-will@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Improve list integrity checking | expand |
On Tue, Mar 24, 2020 at 03:36:27PM +0000, Will Deacon wrote: > Although __list_del() is called from the RCU list implementation, it > omits WRITE_ONCE() when updating the 'prev' pointer for the 'next' node. > This is reasonable because concurrent RCU readers only access the 'next' > pointers. > > Although it's obvious after reading the code, add a comment. > > Cc: Paul E. McKenney <paulmck@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Will Deacon <will@kernel.org> OK, I will take the easy one. ;-) Reviewed-by: Paul E. McKenney <paulmck@kernel.org> > --- > include/linux/list.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/linux/list.h b/include/linux/list.h > index 4d9f5f9ed1a8..ec1f780d1449 100644 > --- a/include/linux/list.h > +++ b/include/linux/list.h > @@ -109,6 +109,7 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) > */ > static inline void __list_del(struct list_head * prev, struct list_head * next) > { > + /* RCU readers don't read the 'prev' pointer */ > next->prev = prev; > WRITE_ONCE(prev->next, next); > } > -- > 2.20.1 >
diff --git a/include/linux/list.h b/include/linux/list.h index 4d9f5f9ed1a8..ec1f780d1449 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -109,6 +109,7 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) */ static inline void __list_del(struct list_head * prev, struct list_head * next) { + /* RCU readers don't read the 'prev' pointer */ next->prev = prev; WRITE_ONCE(prev->next, next); }
Although __list_del() is called from the RCU list implementation, it omits WRITE_ONCE() when updating the 'prev' pointer for the 'next' node. This is reasonable because concurrent RCU readers only access the 'next' pointers. Although it's obvious after reading the code, add a comment. Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Will Deacon <will@kernel.org> --- include/linux/list.h | 1 + 1 file changed, 1 insertion(+)