On Sat, Dec 20, 2008 at 07:10:45PM +1100, Herbert Xu (herbert@xxxxxxxxxxxxxxxxxxx) wrote: > > Hm. So if I get a destructor call from the shared_info, can I go an > > inspect the page refcounts to see if its really the last use? > > The pages that were originally in the shared_info at creation > time may no longer be there by the time it's freed because of > pskb_pull_tail. Things should work fine, since pskb_expand_head() copies whole shared info structure (and thus will copy destructor), get all pages and then copy all pointers into the new skb, and then release old skb's data. So destructor for the pages should not rely on which skb it is called on and check if pages are about to be really freed (i.e. check theirs reference counter). __pskb_pull_tail() is tricky, it just puts some pages it does not want to be present in the skb, but it could be possible to add there destructor callback from the original skb with partial flag (or just having destructor with two parameters: skb and page, and if page is not NULL, then actually only given page is freed, otherwise the whole skb). -- Evgeniy Polyakov -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
