From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: Herbert Xu <herbert@gondor.apana.org.au>,
Steffen Klassert <steffen.klassert@secunet.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] padata: always acquire cpu_hotplug_lock before pinst->lock
Date: Fri, 9 Aug 2019 15:28:56 -0400 [thread overview]
Message-ID: <20190809192857.26585-1-daniel.m.jordan@oracle.com> (raw)
On a 5.2 kernel, lockdep complains when offlining a CPU and writing to a
parallel_cpumask sysfs file.
echo 0 > /sys/devices/system/cpu/cpu1/online
echo ff > /sys/kernel/pcrypt/pencrypt/parallel_cpumask
======================================================
WARNING: possible circular locking dependency detected
5.2.0-padata-base+ #19 Not tainted
------------------------------------------------------
cpuhp/1/13 is trying to acquire lock:
... (&pinst->lock){+.+.}, at: padata_cpu_prep_down+0x37/0x70
but task is already holding lock:
... (cpuhp_state-down){+.+.}, at: cpuhp_thread_fun+0x34/0x240
which lock already depends on the new lock.
padata doesn't take cpu_hotplug_lock and pinst->lock in a consistent
order. Which should be first? CPU hotplug calls into padata with
cpu_hotplug_lock already held, so it should have priority.
Remove the cpu_hotplug_lock acquisition from __padata_stop and hoist it
up to padata_stop, before pd->lock is taken. That fixes a
recursive acquisition of cpu_hotplug_lock in padata_remove_cpu at the
same time:
padata_remove_cpu
mutex_lock(&pinst->lock)
get_online_cpus()
__padata_remove_cpu
__padata_stop
get_online_cpus()
The rest is just switching the order where the two locks are taken
together.
Fixes: 6751fb3c0e0c ("padata: Use get_online_cpus/put_online_cpus")
Fixes: 65ff577e6b6e ("padata: Rearrange set_cpumask functions")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Hello, these two patches are based on all padata fixes now in cryptodev-2.6.
kernel/padata.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/padata.c b/kernel/padata.c
index b60cc3dcee58..d056276a96ce 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -487,9 +487,7 @@ static void __padata_stop(struct padata_instance *pinst)
synchronize_rcu();
- get_online_cpus();
padata_flush_queues(pinst->pd);
- put_online_cpus();
}
/* Replace the internal control structure with a new one. */
@@ -614,8 +612,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
struct cpumask *serial_mask, *parallel_mask;
int err = -EINVAL;
- mutex_lock(&pinst->lock);
get_online_cpus();
+ mutex_lock(&pinst->lock);
switch (cpumask_type) {
case PADATA_CPU_PARALLEL:
@@ -633,8 +631,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
out:
- put_online_cpus();
mutex_unlock(&pinst->lock);
+ put_online_cpus();
return err;
}
@@ -669,9 +667,11 @@ EXPORT_SYMBOL(padata_start);
*/
void padata_stop(struct padata_instance *pinst)
{
+ get_online_cpus();
mutex_lock(&pinst->lock);
__padata_stop(pinst);
mutex_unlock(&pinst->lock);
+ put_online_cpus();
}
EXPORT_SYMBOL(padata_stop);
@@ -739,18 +739,18 @@ int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask)
if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
return -EINVAL;
+ get_online_cpus();
mutex_lock(&pinst->lock);
- get_online_cpus();
if (mask & PADATA_CPU_SERIAL)
cpumask_clear_cpu(cpu, pinst->cpumask.cbcpu);
if (mask & PADATA_CPU_PARALLEL)
cpumask_clear_cpu(cpu, pinst->cpumask.pcpu);
err = __padata_remove_cpu(pinst, cpu);
- put_online_cpus();
mutex_unlock(&pinst->lock);
+ put_online_cpus();
return err;
}
--
2.22.0
next reply other threads:[~2019-08-09 19:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 19:28 Daniel Jordan [this message]
2019-08-09 19:28 ` [PATCH 2/2] padata: validate cpumask without removed CPU during offline Daniel Jordan
2019-08-09 21:06 ` [PATCH v2] " Daniel Jordan
2019-08-12 21:02 ` [PATCH 3/2] padata: initialize usable masks to reflect offlined CPU Daniel Jordan
2019-08-22 3:51 ` Herbert Xu
2019-08-22 22:11 ` Daniel Jordan
2019-08-22 3:50 ` [PATCH v2] padata: validate cpumask without removed CPU during offline Herbert Xu
2019-08-22 22:10 ` Daniel Jordan
2019-08-22 22:53 ` Daniel Jordan
2019-08-15 5:15 ` [PATCH 1/2] padata: always acquire cpu_hotplug_lock before pinst->lock Herbert Xu
2019-08-21 4:14 ` Daniel Jordan
2019-08-21 6:43 ` Herbert Xu
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