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SubjectPossible bug: ASYNC IO with RT Signals in threaded application doesnt work
I have a multithread application which uses ASYNC IO but is RT signal
driven. I have a worker thread which handles all connection and accepts
all data that are received. I use SIGRTMIN as the signal to be delivered
whenever my socket is ready with data. All my threads block SIGRTMIN
including the main thread. In the worker thread I have something like

while (1) {
sigwaitinfo ();
I am never able dequeue SIGRTMIN from the pending signal queue from the
worker thread. If I do the above in the main thread then I am able
dequeue SIGRTMIN from the pending signal queue.

Is this a bug in the kernel or is it a feature. I am also attaching a
patch along with this email which solves the ASYNC IO problem with RT



Bharath Ramesh <>
--- linux-2.6.10/fs/fcntl.c.orig 2004-12-24 16:35:01.000000000 -0500
+++ linux-2.6.10/fs/fcntl.c 2005-03-22 14:30:14.298415152 -0500
@@ -469,7 +469,7 @@ static void send_sigio_to_task(struct ta
si.si_band = band_table[reason - POLL_IN];
si.si_fd = fd;
- if (!send_sig_info(fown->signum, &si, p))
+ if (!send_group_sig_info(fown->signum, &si, p))
/* fall-through: fall back on the old plain SIGIO signal */
case 0:
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