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authorDavid Decotigny <decot@googlers.com>2013-01-11 14:31:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-01-11 14:54:54 -0800
commit896f97ea95c1d29c0520ee0766b66b7f64cb967c (patch)
tree9898ba669c2348294452fcfd5b7b81fe04cb072f /lib/cpu_rmap.c
parent254adaa465c40151df11fc1f88f93e6e86eb61d4 (diff)
downloadlinux-linaro-stable-896f97ea95c1d29c0520ee0766b66b7f64cb967c.tar.gz
lib: cpu_rmap: avoid flushing all workqueues
In some cases, free_irq_cpu_rmap() is called while holding a lock (eg rtnl). This can lead to deadlocks, because it invokes flush_scheduled_work() which ends up waiting for whole system workqueue to flush, but some pending works might try to acquire the lock we are already holding. This commit uses reference-counting to replace irq_run_affinity_notifiers(). It also removes irq_run_affinity_notifiers() altogether. [akpm@linux-foundation.org: eliminate free_cpu_rmap, rename cpu_rmap_reclaim() to cpu_rmap_release(), propagate kref_put() retval from cpu_rmap_put()] Signed-off-by: David Decotigny <decot@googlers.com> Reviewed-by: Ben Hutchings <bhutchings@solarflare.com> Acked-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Or Gerlitz <ogerlitz@mellanox.com> Acked-by: Amir Vadai <amirv@mellanox.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/cpu_rmap.c')
-rw-r--r--lib/cpu_rmap.c54
1 files changed, 49 insertions, 5 deletions
diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index 145dec5267c9..5fbed5caba6e 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -45,6 +45,7 @@ struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags)
if (!rmap)
return NULL;
+ kref_init(&rmap->refcount);
rmap->obj = (void **)((char *)rmap + obj_offset);
/* Initially assign CPUs to objects on a rota, since we have
@@ -63,6 +64,35 @@ struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags)
}
EXPORT_SYMBOL(alloc_cpu_rmap);
+/**
+ * cpu_rmap_release - internal reclaiming helper called from kref_put
+ * @ref: kref to struct cpu_rmap
+ */
+static void cpu_rmap_release(struct kref *ref)
+{
+ struct cpu_rmap *rmap = container_of(ref, struct cpu_rmap, refcount);
+ kfree(rmap);
+}
+
+/**
+ * cpu_rmap_get - internal helper to get new ref on a cpu_rmap
+ * @rmap: reverse-map allocated with alloc_cpu_rmap()
+ */
+static inline void cpu_rmap_get(struct cpu_rmap *rmap)
+{
+ kref_get(&rmap->refcount);
+}
+
+/**
+ * cpu_rmap_put - release ref on a cpu_rmap
+ * @rmap: reverse-map allocated with alloc_cpu_rmap()
+ */
+int cpu_rmap_put(struct cpu_rmap *rmap)
+{
+ return kref_put(&rmap->refcount, cpu_rmap_release);
+}
+EXPORT_SYMBOL(cpu_rmap_put);
+
/* Reevaluate nearest object for given CPU, comparing with the given
* neighbours at the given distance.
*/
@@ -197,8 +227,7 @@ struct irq_glue {
* free_irq_cpu_rmap - free a CPU affinity reverse-map used for IRQs
* @rmap: Reverse-map allocated with alloc_irq_cpu_map(), or %NULL
*
- * Must be called in process context, before freeing the IRQs, and
- * without holding any locks required by global workqueue items.
+ * Must be called in process context, before freeing the IRQs.
*/
void free_irq_cpu_rmap(struct cpu_rmap *rmap)
{
@@ -212,12 +241,18 @@ void free_irq_cpu_rmap(struct cpu_rmap *rmap)
glue = rmap->obj[index];
irq_set_affinity_notifier(glue->notify.irq, NULL);
}
- irq_run_affinity_notifiers();
- kfree(rmap);
+ cpu_rmap_put(rmap);
}
EXPORT_SYMBOL(free_irq_cpu_rmap);
+/**
+ * irq_cpu_rmap_notify - callback for IRQ subsystem when IRQ affinity updated
+ * @notify: struct irq_affinity_notify passed by irq/manage.c
+ * @mask: cpu mask for new SMP affinity
+ *
+ * This is executed in workqueue context.
+ */
static void
irq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask)
{
@@ -230,10 +265,16 @@ irq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask)
pr_warning("irq_cpu_rmap_notify: update failed: %d\n", rc);
}
+/**
+ * irq_cpu_rmap_release - reclaiming callback for IRQ subsystem
+ * @ref: kref to struct irq_affinity_notify passed by irq/manage.c
+ */
static void irq_cpu_rmap_release(struct kref *ref)
{
struct irq_glue *glue =
container_of(ref, struct irq_glue, notify.kref);
+
+ cpu_rmap_put(glue->rmap);
kfree(glue);
}
@@ -258,10 +299,13 @@ int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
glue->notify.notify = irq_cpu_rmap_notify;
glue->notify.release = irq_cpu_rmap_release;
glue->rmap = rmap;
+ cpu_rmap_get(rmap);
glue->index = cpu_rmap_add(rmap, glue);
rc = irq_set_affinity_notifier(irq, &glue->notify);
- if (rc)
+ if (rc) {
+ cpu_rmap_put(glue->rmap);
kfree(glue);
+ }
return rc;
}
EXPORT_SYMBOL(irq_cpu_rmap_add);