On Wed, 2011-06-22 at 18:28 +0530, Yogesh Ashok Powar wrote: > On Wed, Jun 22, 2011 at 05:49:25AM -0700, Johannes Berg wrote: > > On Wed, 2011-06-22 at 18:01 +0530, Yogesh Ashok Powar wrote: > > > > Will work on some other logic. > > > > > > Following is the complete V2-patch > > > > > > v2 changes: a) Moved counter++ before __ieee80211_key_replace in > > > key_link() > > > b) Moved crypto_tx_tailroom_needed_cnt to sdata resolve > > > issue with multiple sdata instances in hw reset. > > > > Looks good. Now I'm just worried about memory and compiler barriers that > > may be needed so the counter update doesn't move after anything else... > > Hmm. > > I some how feel that synchronize_net may be replaced with > synchronize_rcu and still the race wont happen. > > So the new logic would be > - counter++ <-- Here keys are not added or deleted > so rcu readers wont have problem > with extra space allocated. > > - synchronize_rcu <-- This will flush existing readers. Again > new readers will have no problem with extra > space allocated. > > Let me know your opinion on this. It doesn't really matter -- synchronize_net() is exactly the same as synchronize_rcu(). What I'm worried about is that there's no memory barrier after the counter update, so how do we know it cannot happen after synchronize_rcu()? I think we need something like rcu_assign_pointer() but I don't see rcu_assign_index() (any more?) johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
