80 lines
2.7 KiB
Diff
80 lines
2.7 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 26 Jul 2018 18:52:00 +0200
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Subject: [PATCH] crypto: cryptd - add a lock instead
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preempt_disable/local_bh_disable
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.5-rt3.tar.xz
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cryptd has a per-CPU lock which protected with local_bh_disable() and
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preempt_disable().
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Add an explicit spin_lock to make the locking context more obvious and
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visible to lockdep. Since it is a per-CPU lock, there should be no lock
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contention on the actual spinlock.
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There is a small race-window where we could be migrated to another CPU
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after the cpu_queue has been obtain. This is not a problem because the
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actual ressource is protected by the spinlock.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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crypto/cryptd.c | 19 +++++++++----------
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1 file changed, 9 insertions(+), 10 deletions(-)
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--- a/crypto/cryptd.c
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+++ b/crypto/cryptd.c
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@@ -39,6 +39,7 @@ MODULE_PARM_DESC(cryptd_max_cpu_qlen, "S
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struct cryptd_cpu_queue {
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struct crypto_queue queue;
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struct work_struct work;
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+ spinlock_t qlock;
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};
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struct cryptd_queue {
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@@ -117,6 +118,7 @@ static int cryptd_init_queue(struct cryp
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cpu_queue = per_cpu_ptr(queue->cpu_queue, cpu);
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crypto_init_queue(&cpu_queue->queue, max_cpu_qlen);
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INIT_WORK(&cpu_queue->work, cryptd_queue_worker);
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+ spin_lock_init(&cpu_queue->qlock);
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}
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pr_info("cryptd: max_cpu_qlen set to %d\n", max_cpu_qlen);
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return 0;
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@@ -141,8 +143,10 @@ static int cryptd_enqueue_request(struct
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struct cryptd_cpu_queue *cpu_queue;
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atomic_t *refcnt;
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- cpu = get_cpu();
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- cpu_queue = this_cpu_ptr(queue->cpu_queue);
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+ cpu_queue = raw_cpu_ptr(queue->cpu_queue);
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+ spin_lock_bh(&cpu_queue->qlock);
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+ cpu = smp_processor_id();
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+
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err = crypto_enqueue_request(&cpu_queue->queue, request);
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refcnt = crypto_tfm_ctx(request->tfm);
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@@ -158,7 +162,7 @@ static int cryptd_enqueue_request(struct
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atomic_inc(refcnt);
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out_put_cpu:
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- put_cpu();
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+ spin_unlock_bh(&cpu_queue->qlock);
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return err;
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}
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@@ -174,16 +178,11 @@ static void cryptd_queue_worker(struct w
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cpu_queue = container_of(work, struct cryptd_cpu_queue, work);
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/*
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* Only handle one request at a time to avoid hogging crypto workqueue.
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- * preempt_disable/enable is used to prevent being preempted by
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- * cryptd_enqueue_request(). local_bh_disable/enable is used to prevent
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- * cryptd_enqueue_request() being accessed from software interrupts.
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*/
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- local_bh_disable();
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- preempt_disable();
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+ spin_lock_bh(&cpu_queue->qlock);
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backlog = crypto_get_backlog(&cpu_queue->queue);
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req = crypto_dequeue_request(&cpu_queue->queue);
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- preempt_enable();
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- local_bh_enable();
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+ spin_unlock_bh(&cpu_queue->qlock);
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if (!req)
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return;
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