Re: [Xenomai-help] xnpipe EPOLLIN starvation

[Philippe Gerum <rpm@xenomai.org>]

Filip Van Rillaer wrote:
> Hello Gilles,
> 
> EPOLLET is indeed enabled.
> The first time EPOLLIN is received in the 2nd domain, I do a read (it
> receives 1 byte in a buffer of 256).  So the read is exhausted and I
> expect that the next time data arrives I should get the EPOLLIN (as it
> BECOMES readable).  But even adding another read (which returns -EAGAIN)
> did not make it possible to receive the EPOLLIN when a little bit later
> data is written at the Xenomai side of the xnpipe.
> 

Does this help?

--- ksrc/nucleus/pipe.c	(revision 4044)
+++ ksrc/nucleus/pipe.c	(working copy)
@@ -1029,9 +1029,12 @@
 {
 	xnpipe_state_t *state = (xnpipe_state_t *)file->private_data;
 	unsigned r_mask = 0, w_mask = 0;
+	spl_t s;

 	poll_wait(file, &state->readq, pt);

+	xnlock_get_irqsave(&nklock, s);
+
 	if (testbits(state->status, XNPIPE_KERN_CONN))
 		w_mask |= (POLLOUT | POLLWRNORM);

@@ -1046,6 +1049,8 @@
 		 */
 		xnpipe_enqueue_wait(state, XNPIPE_USER_WREAD);

+	xnlock_put_irqrestore(&nklock, s);
+
 	/*
 	 * A descriptor is always ready for writing with the current
 	 * implementation, so there is no need to have/handle the

-- 
Philippe.