Reviewed by: julian and (hsu?)

Submitted by:	 John Birrel(L?)

changes for threadsafe operations

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/libc/sys/flock.2 b/lib/libc/sys/flock.2
index bb6abb7..5ec080c 100644
--- a/lib/libc/sys/flock.2
+++ b/lib/libc/sys/flock.2
@@ -109,6 +109,28 @@ forks and the child explicitly unlocks the file, the parent will
 lose its lock.
 .Pp
 Processes blocked awaiting a lock may be awakened by signals.
+.Sh IMPLEMENTATION NOTES
+.Pp
+In the non-threaded library
+.Fn flock
+is implemented as the
+.Va flock
+syscall.
+.Pp
+In the threaded library, the
+.Va flock
+syscall is assembled to
+.Fn _thread_sys_flock
+and
+.Fn flock
+is implemented as a function which locks
+.Va fd
+for read and write, then calls
+.Fn _thread_sys_flock .
+Before returning,
+.Fn flock
+unlocks
+.Va fd .
 .Sh RETURN VALUES
 Zero is returned if the operation was successful;
 on an error a -1 is returned and an error code is left in