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	Thu, 11 Jan 2007 15:58:27 +0100
Subject: Re: [Qemu-devel] [PATCH] better handling of removal in
	IOHandlerRecord list
From: jerome Arbez-Gindre <jerome.arbez-gindre@laposte.net>
In-Reply-To: <1168523801.4765.10.camel@bibi>
References: <1168446890.24524.11.camel@bibi> <1168523801.4765.10.camel@bibi>
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Date: Thu, 11 Jan 2007 16:00:10 +0100
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To: qemu-devel@nongnu.org

On Thu, 2007-01-11 at 14:56 +0100, jerome Arbez-Gindre wrote:
> On Wed, 2007-01-10 at 17:34 +0100, jerome Arbez-Gindre wrote:
> > Hi,
> > 
> > by a call to qemu_set_fd_handler(fd,NULL,NULL,NULL) in the fd_read
> > callback, I have generated a "Segmentation fault" in vl.c.
> > 
> > My solution is not very smart... but it is very simple.
> 
> I reply to myself because I did not sleep last night:
> 
> Here is the fix without the double IOHandlerRecord list iteration.

Here is a little fix to handle the case when a IOHandler removes an
other IOHandler.

--- vl.c.mine	2007-01-11 15:06:47.000000000 +0100
+++ vl.c	2007-01-11 15:27:27.000000000 +0100
@@ -5912,11 +5912,13 @@
         pioh = &first_io_handler ;
         for(ioh = first_io_handler; ioh != NULL; ioh = ioh_next) {
             ioh_next = ioh->next;
-            if (FD_ISSET(ioh->fd, &rfds)) {
+            /* ioh->fd_read could have been set to null by an other
+               IOHandlerRecord callback */
+            if (ioh->fd_read && FD_ISSET(ioh->fd, &rfds)) {
                 ioh->fd_read(ioh->opaque);
             }
             /* ioh->fd_write could have been set to null */
-            if ((ioh->fd_write) && (FD_ISSET(ioh->fd, &wfds))) {
+            if (ioh->fd_write && FD_ISSET(ioh->fd, &wfds)) {
                 ioh->fd_write(ioh->opaque);
             }
             /* the ioh could have been supressed */