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>
diff --git a/include/linux/cpu_rmap.h b/include/linux/cpu_rmap.h
index ac3bbb5..1739510 100644
--- a/include/linux/cpu_rmap.h
+++ b/include/linux/cpu_rmap.h
@@ -13,9 +13,11 @@
#include <linux/cpumask.h>
#include <linux/gfp.h>
#include <linux/slab.h>
+#include <linux/kref.h>
/**
* struct cpu_rmap - CPU affinity reverse-map
+ * @refcount: kref for object
* @size: Number of objects to be reverse-mapped
* @used: Number of objects added
* @obj: Pointer to array of object pointers
@@ -23,6 +25,7 @@
* based on affinity masks
*/
struct cpu_rmap {
+ struct kref refcount;
u16 size, used;
void **obj;
struct {
@@ -33,15 +36,7 @@
#define CPU_RMAP_DIST_INF 0xffff
extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
-
-/**
- * free_cpu_rmap - free CPU affinity reverse-map
- * @rmap: Reverse-map allocated with alloc_cpu_rmap(), or %NULL
- */
-static inline void free_cpu_rmap(struct cpu_rmap *rmap)
-{
- kfree(rmap);
-}
+extern int cpu_rmap_put(struct cpu_rmap *rmap);
extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
extern int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,