From f854ce4d0a3f7281b5b99b28dd028abe21c1b0c8 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sat, 12 Aug 2023 17:10:42 -0400 Subject: bcachefs: six locks: Guard against wakee exiting in __six_lock_wakeup() Signed-off-by: Kent Overstreet --- fs/bcachefs/six.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'fs/bcachefs') diff --git a/fs/bcachefs/six.c b/fs/bcachefs/six.c index 0473aa4dd18a..7faa27310de4 100644 --- a/fs/bcachefs/six.c +++ b/fs/bcachefs/six.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include "six.h" @@ -221,7 +222,12 @@ again: if (ret <= 0) goto unlock; - task = w->task; + /* + * Similar to percpu_rwsem_wake_function(), we need to guard + * against the wakee noticing w->lock_acquired, returning, and + * then exiting before we do the wakeup: + */ + task = get_task_struct(w->task); __list_del(w->list.prev, w->list.next); /* * The release barrier here ensures the ordering of the @@ -232,6 +238,7 @@ again: */ smp_store_release(&w->lock_acquired, true); wake_up_process(task); + put_task_struct(task); } six_clear_bitmask(lock, SIX_LOCK_WAITING_read << lock_type); -- cgit v1.2.3