dmasound close timeout

Hi !

The dmasound driver occasionally hangs a process on exit, apparently, there is a possible case where the sound HW stops draining output samples and the driver waits forever in its release() callback. It should check for signals(), but it seems signal_pending() never returns 1 when the process is beeing killed (implicit release() of files on exit).

This patch adds a safety timeout to the release() function to make sure we can at least close the driver. I'll try to find the reason we aren't driving samples later, but it is better to have a safety just incase the sound clock goes berserk for some reason.

Ben.

diff -urN linux-2.5/sound/oss/dmasound/dmasound_core.c linuxppc-2.5-benh/sound/oss/dmasound/dmasound_core.c
@@ -1004,6 +1004,7 @@
 static int sq_fsync(struct file *filp, struct dentry *dentry)
 {
 	int rc = 0;
+	int timeout = 5;
 
 	write_sq.syncing |= 1;
 	sq_play();	/* there may be an incomplete frame waiting */

@@ -1018,6 +1019,12 @@
 			rc = -EINTR;
 			break;
 		}
+		if (!--timeout) {
+			printk(KERN_WARNING "dmasound: Timeout draining output\n");
+			sq_reset_output();
+			rc = -EIO;
+			break;
+		}
 	}
 
 	/* flag no sync regardless of whether we had a DSP_POST or not */