Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [patch] fs: aio fix rcu lookup | Date | Wed, 19 Jan 2011 15:32:54 -0500 |
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Nick Piggin <npiggin@gmail.com> writes:
> On Thu, Jan 20, 2011 at 6:46 AM, Jeff Moyer <jmoyer@redhat.com> wrote: >> Jeff Moyer <jmoyer@redhat.com> writes: >> >>> Jan Kara <jack@suse.cz> writes: >>> >>>> But 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. You'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-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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