@@ -158,3 +158,11 @@ when a padata instance is no longer needed:
This function will busy-wait while any remaining tasks are completed, so it
might be best not to call it while there is work outstanding. Shutting
down the workqueue, if necessary, should be done separately.
+
+While you cannot have more than 2^31-1 taks submitted at the same time, this
+maximum is well above what you might actually want to be submitted. Thus,
+callers are encouraged to determine their maximum latency/memory/throughput
+constraints, and limit calls to padata_do_parallel() based on the current
+queue length, which can be determined with:
+
+ int padata_queue_len(struct padata_instance *pinst);
@@ -70,6 +70,8 @@ struct pcrypt_aead_ctx {
unsigned int cb_cpu;
};
+#define MAX_OBJ_NUM 1000
+
static int pcrypt_do_parallel(struct padata_priv *padata, unsigned int *cb_cpu,
struct padata_pcrypt *pcrypt)
{
@@ -78,6 +80,9 @@ static int pcrypt_do_parallel(struct padata_priv *padata, unsigned int *cb_cpu,
cpu = *cb_cpu;
+ if (padata_queue_len(pcrypt->pinst) >= MAX_OBJ_NUM)
+ return -EBUSY;
+
rcu_read_lock_bh();
cpumask = rcu_dereference_bh(pcrypt->cb_cpumask);
if (cpumask_test_cpu(cpu, cpumask->mask))
@@ -3,6 +3,7 @@
*
* Copyright (C) 2008, 2009 secunet Security Networks AG
* Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
+ * Copyright (C) 2016, 2017 Jason A. Donenfeld <Jason@zx2c4.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
@@ -181,4 +182,5 @@ extern int padata_register_cpumask_notifier(struct padata_instance *pinst,
struct notifier_block *nblock);
extern int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
struct notifier_block *nblock);
+extern int padata_queue_len(struct padata_instance *pinst);
#endif
@@ -5,6 +5,7 @@
*
* Copyright (C) 2008, 2009 secunet Security Networks AG
* Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
+ * Copyright (C) 2016, 2017 Jason A. Donenfeld <Jason@zx2c4.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
@@ -32,8 +33,6 @@
#include <linux/rcupdate.h>
#include <linux/module.h>
-#define MAX_OBJ_NUM 1000
-
static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
{
int cpu, target_cpu;
@@ -122,7 +121,7 @@ int padata_do_parallel(struct padata_instance *pinst,
if ((pinst->flags & PADATA_RESET))
goto out;
- if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
+ if (unlikely(atomic_read(&pd->refcnt) == INT_MAX))
goto out;
err = 0;
@@ -1021,6 +1020,21 @@ void padata_free(struct padata_instance *pinst)
}
EXPORT_SYMBOL(padata_free);
+/**
+ * padata_queue_len - retreive the number of in progress jobs
+ *
+ * @padata_inst: padata instance from which to read the queue size
+ */
+int padata_queue_len(struct padata_instance *pinst)
+{
+ int len;
+ rcu_read_lock_bh();
+ len = atomic_read(&rcu_dereference_bh(pinst->pd)->refcnt);
+ rcu_read_unlock_bh();
+ return len;
+}
+EXPORT_SYMBOL(padata_queue_len);
+
#ifdef CONFIG_HOTPLUG_CPU
static __init int padata_driver_init(void)
Allow users of padata to determine the queue length themselves, via this added helper function, so that we can later remove the hard-coded 1000- job limit. We thus add a helper function, and then move the limiting functionality to pcrypt-proper, since it was the only current consumer relying on the 1000-job limit. We do, however, impose a limit on padata so that the reference count does not have an integer overflow. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- Documentation/padata.txt | 8 ++++++++ crypto/pcrypt.c | 5 +++++ include/linux/padata.h | 2 ++ kernel/padata.c | 20 +++++++++++++++++--- 4 files changed, 32 insertions(+), 3 deletions(-)