Messages in this thread | | | Date | Wed, 28 May 2014 21:21:00 -0700 | Subject | Re: fs/dcache.c - BUG: soft lockup - CPU#5 stuck for 22s! [systemd-udevd:1667] | From | Linus Torvalds <> |
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On Wed, May 28, 2014 at 8:11 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > Here's an updated patch, hopefully slightly less vomit-inducing.
Hmm. Less vomit-inducing, except for this part:
> dentry = list_entry(list->prev, struct dentry, d_lru); > + > + parent = NULL; > spin_lock(&dentry->d_lock); > + if (!IS_ROOT(dentry)) { > + parent = dentry->d_parent; > + if (unlikely(!spin_trylock(&parent->d_lock))) { > + spin_unlock(&dentry->d_lock); > + parent = NULL; > + read_seqlock_excl(&rename_lock); > + if (!IS_ROOT(dentry)) { > + parent = dentry->d_parent; > + spin_lock(&parent->d_lock); > + } > + read_sequnlock_excl(&rename_lock); > + spin_lock(&dentry->d_lock); > + } > + }
Ugh, that just *screams* for a helper function. Something like
parent = get_parent_and_lock(dentry);
or whatever, with that trylock/renamelock dance separated out. The rule would be that it would lock the "dentry", and return the (similarly locked) parent. Or NULL for a root dentry, of course.
Please?
Linus
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