lkml.org 
[lkml]   [2020]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [RFC PATCH 02/21] list: Remove hlist_nulls_unhashed_lockless()
    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
    >

    \
     
     \ /
      Last update: 2020-03-31 01:08    [W:3.032 / U:0.284 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site