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srcu: Add cleanup_srcu_struct_quiesced()

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The current cleanup_srcu_struct() flushes work, which prevents it
from being invoked from some workqueue contexts, as well as from
atomic (non-blocking) contexts.  This patch therefore introduced a
cleanup_srcu_struct_quiesced(), which can be invoked only after all
activity on the specified srcu_struct has completed.  This restriction
allows cleanup_srcu_struct_quiesced() to be invoked from workqueue
contexts as well as from atomic contexts.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Nitzan Carmi <nitzanc@mellanox.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Paul E. McKenney
2018-04-05 17:19:17 -07:00
parent 17672480fb
commit f7194ac32c
4 changed files with 64 additions and 18 deletions
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30
kernel/rcu/srcutree.c
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@@ -366,24 +366,28 @@ static unsigned long srcu_get_delay(struct srcu_struct *sp)
return SRCU_INTERVAL;
}
/**
* cleanup_srcu_struct - deconstruct a sleep-RCU structure
* @sp: structure to clean up.
*
* Must invoke this after you are finished using a given srcu_struct that
* was initialized via init_srcu_struct(), else you leak memory.
*/
void cleanup_srcu_struct(struct srcu_struct *sp)
/* Helper for cleanup_srcu_struct() and cleanup_srcu_struct_quiesced(). */
void _cleanup_srcu_struct(struct srcu_struct *sp, bool quiesced)
{
int cpu;
if (WARN_ON(!srcu_get_delay(sp)))
return; /* Leakage unless caller handles error. */
return; /* Just leak it! */
if (WARN_ON(srcu_readers_active(sp)))
return; /* Leakage unless caller handles error. */
flush_delayed_work(&sp->work);
return; /* Just leak it! */
if (quiesced) {
if (WARN_ON(delayed_work_pending(&sp->work)))
return; /* Just leak it! */
} else {
flush_delayed_work(&sp->work);
}
for_each_possible_cpu(cpu)
flush_delayed_work(&per_cpu_ptr(sp->sda, cpu)->work);
if (quiesced) {
if (WARN_ON(delayed_work_pending(&per_cpu_ptr(sp->sda, cpu)->work)))
return; /* Just leak it! */
} else {
flush_delayed_work(&per_cpu_ptr(sp->sda, cpu)->work);
}
if (WARN_ON(rcu_seq_state(READ_ONCE(sp->srcu_gp_seq)) != SRCU_STATE_IDLE) ||
WARN_ON(srcu_readers_active(sp))) {
pr_info("%s: Active srcu_struct %p state: %d\n", __func__, sp, rcu_seq_state(READ_ONCE(sp->srcu_gp_seq)));
@@ -392,7 +396,7 @@ void cleanup_srcu_struct(struct srcu_struct *sp)
free_percpu(sp->sda);
sp->sda = NULL;
}
EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
EXPORT_SYMBOL_GPL(_cleanup_srcu_struct);
/*
* Counts the new reader in the appropriate per-CPU element of the