uml: aIO deadlock avoidance

Allow deadlocks to be avoided in the AIO code by setting the pipe to the I/O
thread non-blocking.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
index 5d258eb4f506..9bf944f6a1db 100644
--- a/arch/um/os-Linux/aio.c
+++ b/arch/um/os-Linux/aio.c
@@ -221,6 +221,11 @@ static int init_aio_24(void)
 
         aio_req_fd_w = fds[0];
         aio_req_fd_r = fds[1];
+
+        err = os_set_fd_block(aio_req_fd_w, 0);
+        if(err)
+                goto out_close_pipe;
+
         err = run_helper_thread(not_aio_thread, NULL,
                                 CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
         if(err < 0)