On 05/03/2016 12:23 AM, Benjamin Marzinski wrote: > On Wed, Apr 27, 2016 at 01:10:37PM +0200, Hannes Reinecke wrote: >> Instead of generating the cookie internally we should be >> passing in the cookie to dm_addmap(). > > These look like they could actually cause problems. With > dm_addmap_create and dm_addmap_reload, you could be in a situation where > you get a cookie back on your first call to dm_task_set_cookie, wait on > it, so that cookie is no longer in use, and then use that same cookie > id again. It's possible that after you first waited on the cookie, > someone else could have been given that cookie id (without looking into > the dm cookie code more, I'm not sure how likely this is). If that is > so, the second call to dm_addmap would be adding its command to the list > of other commands for that cookie (since you are allowed to use a cookie > for multiple dm commands). Calling dm_udev_wait would make it wait of > all the commands. > > We can use a cookie multiple times and then wait on it once. But we > can't keep reusing the cookie after we've waited on it, because someone > else could be using the same cookie. > Ah. Thanks for the clarification. I'll be looking into it. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
