Messages in this thread | | | Date | Thu, 15 Mar 2012 23:08:22 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [patch 0/5] seqlock consolidation |
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On Thu, 15 Mar 2012, Al Viro wrote:
> On Thu, Mar 15, 2012 at 08:17:12PM +0100, Thomas Gleixner wrote: > > > + hits += replace_path(&fs->root, old_root, new_root); > > > + hits += replace_path(&fs->pwd, old_root, new_root); > > > > Wouldn't it be simpler to just do: > > > > + count += replace_path(&fs->root, old_root, new_root); > > + count += replace_path(&fs->pwd, old_root, new_root); > > > > > + write_seqcount_end(&fs->seq); > > > + while (hits--) { > > > count++; > > > > Instead of that loop ? > > This loop also contains path_get_longterm() and we need to do it before > dropping fs->lock. We are holding a reference to new_root, all right, > but once it's place into ->fs->{root,pwd} of another task and ->fs->lock > is dropped, there's nothing to stop that task of doing chdir() and dropping > its reference. Which could outweight the single reference we are holding > pretty soon...
Oops, sorry I missed that path_get_longterm() in the loop due to the +/- forrest around it.
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