diff options
| -rw-r--r-- | kernel/unwind/deferred.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/kernel/unwind/deferred.c b/kernel/unwind/deferred.c index 2311b725d691..a5ef1c1f915e 100644 --- a/kernel/unwind/deferred.c +++ b/kernel/unwind/deferred.c @@ -41,7 +41,7 @@ static inline bool try_assign_cnt(struct unwind_task_info *info, u32 cnt) #define UNWIND_MAX_ENTRIES \ ((SZ_4K - sizeof(struct unwind_cache)) / sizeof(long)) -/* Guards adding to and reading the list of callbacks */ +/* Guards adding to or removing from the list of callbacks */ static DEFINE_MUTEX(callback_mutex); static LIST_HEAD(callbacks); @@ -49,6 +49,7 @@ static LIST_HEAD(callbacks); /* Zero'd bits are available for assigning callback users */ static unsigned long unwind_mask = RESERVED_BITS; +DEFINE_STATIC_SRCU(unwind_srcu); static inline bool unwind_pending(struct unwind_task_info *info) { @@ -174,8 +175,9 @@ static void unwind_deferred_task_work(struct callback_head *head) cookie = info->id.id; - guard(mutex)(&callback_mutex); - list_for_each_entry(work, &callbacks, list) { + guard(srcu)(&unwind_srcu); + list_for_each_entry_srcu(work, &callbacks, list, + srcu_read_lock_held(&unwind_srcu)) { if (test_bit(work->bit, &bits)) { work->func(work, &trace, cookie); if (info->cache) @@ -213,7 +215,7 @@ int unwind_deferred_request(struct unwind_work *work, u64 *cookie) { struct unwind_task_info *info = ¤t->unwind_info; unsigned long old, bits; - unsigned long bit = BIT(work->bit); + unsigned long bit; int ret; *cookie = 0; @@ -230,6 +232,14 @@ int unwind_deferred_request(struct unwind_work *work, u64 *cookie) if (WARN_ON_ONCE(!CAN_USE_IN_NMI && in_nmi())) return -EINVAL; + /* Do not allow cancelled works to request again */ + bit = READ_ONCE(work->bit); + if (WARN_ON_ONCE(bit < 0)) + return -EINVAL; + + /* Only need the mask now */ + bit = BIT(bit); + guard(irqsave)(); *cookie = get_cookie(info); @@ -281,10 +291,15 @@ void unwind_deferred_cancel(struct unwind_work *work) return; guard(mutex)(&callback_mutex); - list_del(&work->list); + list_del_rcu(&work->list); + + /* Do not allow any more requests and prevent callbacks */ + work->bit = -1; __clear_bit(bit, &unwind_mask); + synchronize_srcu(&unwind_srcu); + guard(rcu)(); /* Clear this bit from all threads */ for_each_process_thread(g, t) { @@ -307,7 +322,7 @@ int unwind_deferred_init(struct unwind_work *work, unwind_callback_t func) work->bit = ffz(unwind_mask); __set_bit(work->bit, &unwind_mask); - list_add(&work->list, &callbacks); + list_add_rcu(&work->list, &callbacks); work->func = func; return 0; } |