Re: [announce] [patch] Voluntary Kernel Preemption Patch

Ingo Molnar
2004-07-19T10:33:01Z

* Zwane Mwaikambo <zwane@linuxpower.ca> wrote:

> Looks like some of the voluntary preemption changes might need some
> eyeballing too. This appears to be a use after free, probably since we
> unlocked j_{list,state}_lock.

thx - this is the new __journal_clean_checkpoint_list() chunk:

--- linux/fs/jbd/checkpoint.c.orig
+++ linux/fs/jbd/checkpoint.c
@@ -465,6 +470,7 @@ int __journal_clean_checkpoint_list(jour
transaction_t *transaction, *last_transaction, *next_transaction;
int ret = 0;

+retry:
transaction = journal->j_checkpoint_transactions;
if (transaction == 0)
goto out;
@@ -487,6 +493,14 @@ int __journal_clean_checkpoint_list(jour
/* Use trylock because of the ranknig */
if (jbd_trylock_bh_state(jh2bh(jh)))
ret += __try_to_free_cp_buf(jh);
+ if (voluntary_need_resched()) {
+ spin_unlock(&journal->j_list_lock);
+ spin_unlock(&journal->j_state_lock);
+ voluntary_resched();
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&journal->j_list_lock);
+ goto retry;
+ }
} while (jh != last_jh);
}
} while (transaction != last_transaction);