Nick Piggin <npiggin@xxxxxxxxx> writes: > On Thu, Jan 20, 2011 at 6:46 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: >> Jeff Moyer <jmoyer@xxxxxxxxxx> writes: >> >>> Jan Kara <jack@xxxxxxx> writes: >>> >>>> ÂBut there's the second race I describe making it possible >>>> for new IO to be created after io_destroy() has waited for all IO to >>>> finish... >>> >>> Can't that be solved by introducing memory barriers around the accesses >>> to ->dead? >> >> Upon further consideration, I don't think so. >> >> Given the options, I think adding the synchronize rcu to the io_destroy >> path is the best way forward. ÂYou're already waiting for a bunch of >> queued I/O to finish, so there is no guarantee that you're going to >> finish that call quickly. > > I think synchronize_rcu() is not something to sprinkle around outside > very slow paths. It can be done without synchronize_rcu. I'm not sure I understand what you're saying. Do you mean to imply that io_destroy is not a very slow path? Because it is. I prefer a solution that doesn't re-architecht things in order to solve a theoretical issue that's never been observed. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
