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[PATCH] rcu_process_callbacks: don't cli() while testing ->nxtlist

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__rcu_process_callbacks() disables interrupts to protect itself from
call_rcu() which adds new entries to ->nxtlist.

However we can check "->nxtlist != NULL" with interrupts enabled, we can't
get "false positives" because call_rcu() can only change this condition
from 0 to 1.

Tested with rcutorture.ko.

Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Dipankar Sarma <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Oleg Nesterov authored and Linus Torvalds committed 2006-03-24 07:33:20 -08:00
1 parent cba9f33d13
commit caa9ee771d
1 file changed
+2 -3
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kernel/rcupdate.c
+2 -3
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@@ -416,8 +416,8 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
rdp->curtail = &rdp->curlist;
}
local_irq_disable();
if (rdp->nxtlist && !rdp->curlist) {
local_irq_disable();
rdp->curlist = rdp->nxtlist;
rdp->curtail = rdp->nxttail;
rdp->nxtlist = NULL;
@@ -442,9 +442,8 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
rcu_start_batch(rcp);
spin_unlock(&rcp->lock);
}
} else {
local_irq_enable();
}
rcu_check_quiescent_state(rcp, rdp);
if (rdp->donelist)
rcu_do_batch(rdp);