diff options
| -rw-r--r-- | lib/libc/sys/_umtx_op.2 | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/lib/libc/sys/_umtx_op.2 b/lib/libc/sys/_umtx_op.2 index 0c8025a..bd4ad3b 100644 --- a/lib/libc/sys/_umtx_op.2 +++ b/lib/libc/sys/_umtx_op.2 @@ -28,7 +28,7 @@ .\" .\" $FreeBSD$ .\" -.Dd May 17, 2016 +.Dd May 29, 2016 .Dt _UMTX_OP 2 .Os .Sh NAME @@ -1041,6 +1041,20 @@ with the byte addressed by the if any. Only normal mutexes are supported by the request. The sleep queue is always one for a normal mutex type. +.Pp +This request is deprecated in favor of +.Dv UMTX_OP_MUTEX_WAKE2 +since mutexes using it cannot synchronize their own destruction. +That is, the +.Dv m_owner +word has already been set to +.Dv UMUTEX_UNOWNED +when this request is made, +so that another thread can lock, unlock and destroy the mutex +(if no other thread uses the mutex afterwards). +Clearing the +.Dv UMUTEX_CONTESTED +bit may then modify freed memory. .It Dv UMTX_OP_MUTEX_WAKE2 Check if a umutex is unlocked and wake up a waiter. The arguments for the request are: |
