[dm-devel] race bugs

[Christophe Varoqui]

applied, thanks.

On Mon, Jul 18, 2005 at 05:56:04PM -0500, Benjamin Marzinski wrote:
> I was looking at the waitevent thread, and I noticed some issues. Since the
> cancellation type is asynchronous, the thread can get cancelled at any
> moment. This can cause bugs. For instance, the double removal of the dm task
> structure that just got fixed can still show up if the thread were cancelled
> after it was freed but before it was set to NULL, there were other issues
> like this in update_multpath. It seems like the easiest way to fix this is to
> set some defined cancellation points. So that's what this does.
> 
> 
> -Ben

> diff -urpN mp-devel/multipathd/main.c mp-devel-patched/multipathd/main.c
> --- mp-devel/multipathd/main.c	2005-07-18 10:21:17.000000000 -0500
> +++ mp-devel-patched/multipathd/main.c	2005-07-18 17:52:46.385426160 -0500
> @@ -350,7 +350,6 @@ waiteventloop (struct event_thread * wai
>  
>  	dm_task_no_open_count(waiter->dmt);
>  
> -	pthread_testcancel();
>  	dm_task_run(waiter->dmt);
>  	pthread_testcancel();
>  	dm_task_destroy(waiter->dmt);
> @@ -404,7 +403,6 @@ waitevent (void * et)
>  	mlockall(MCL_CURRENT | MCL_FUTURE);
>  
>  	waiter = (struct event_thread *)et;
> -	pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
>  	pthread_cleanup_push(free_waiter, et);
>  
>  	while (1) {
> @@ -413,7 +411,9 @@ waitevent (void * et)
>  		if (r < 0)
>  			break;
>  
> +		pthread_testcancel();
>  		sleep(r);
> +		pthread_testcancel();
>  	}
>  
>  	pthread_cleanup_pop(1);

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