Merge branch 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

c798360c · Linus Torvalds <[email protected]> · 2014-10-10 07:26:02 -04:00

Pull percpu updates from Tejun Heo:
 "A lot of activities on percpu front.  Notable changes are...

   - percpu allocator now can take @gfp.  If @gfp doesn't contain
     GFP_KERNEL, it tries to allocate from what's already available to
     the allocator and a work item tries to keep the reserve around
     certain level so that these atomic allocations usually succeed.

     This will replace the ad-hoc percpu memory pool used by
     blk-throttle and also be used by the planned blkcg support for
     writeback IOs.

     Please note that I noticed a bug in how @gfp is interpreted while
     preparing this pull request and applied the fix 6ae833c7fe0c
     ("percpu: fix how @gfp is interpreted by the percpu allocator")
     just now.

   - percpu_ref now uses longs for percpu and global counters instead of
     ints.  It leads to more sparse packing of the percpu counters on
     64bit machines but the overhead should be negligible and this
     allows using percpu_ref for refcnting pages and in-memory objects
     directly.

   - The switching between percpu and single counter modes of a
     percpu_ref is made independent of putting the base ref and a
     percpu_ref can now optionally be initialized in single or killed
     mode.  This allows avoiding percpu shutdown latency for cases where
     the refcounted objects may be synchronously created and destroyed
     in rapid succession with only a fraction of them reaching fully
     operational status (SCSI probing does this when combined with
     blk-mq support).  It's also planned to be used to implement forced
     single mode to detect underflow more timely for debugging.

  There's a separate branch percpu/for-3.18-consistent-ops which cleans
  up the duplicate percpu accessors.  That branch causes a number of
  conflicts with s390 and other trees.  I'll send a separate pull
  request w/ resolutions once other branches are merged"

* 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (33 commits)
  percpu: fix how @gfp is interpreted by the percpu allocator
  blk-mq, percpu_ref: start q->mq_usage_counter in atomic mode
  percpu_ref: make INIT_ATOMIC and switch_to_atomic() sticky
  percpu_ref: add PERCPU_REF_INIT_* flags
  percpu_ref: decouple switching to percpu mode and reinit
  percpu_ref: decouple switching to atomic mode and killing
  percpu_ref: add PCPU_REF_DEAD
  percpu_ref: rename things to prepare for decoupling percpu/atomic mode switch
  percpu_ref: replace pcpu_ prefix with percpu_
  percpu_ref: minor code and comment updates
  percpu_ref: relocate percpu_ref_reinit()
  Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe"
  Revert "percpu: free percpu allocation info for uniprocessor system"
  percpu-refcount: make percpu_ref based on longs instead of ints
  percpu-refcount: improve WARN messages
  percpu: fix locking regression in the failure path of pcpu_alloc()
  percpu-refcount: add @gfp to percpu_ref_init()
  proportions: add @gfp to init functions
  percpu_counter: add @gfp to percpu_counter_init()
  percpu_counter: make percpu_counters_lock irq-safe
  ...

Commit: c798360cd1438090d51eeaa8e67985da11362eba
Parents: b211e9d7 · 6ae833c7

Merge commit. Changes below are compared with the first parent: b211e9d7.

Changes

39 files changed · +879 −444

File	Status	Add	Del	Content
arch/x86/kvm/mmu.c	modified	+1	−1	View file
block/blk-mq-sysfs.c	modified	+6	−0	View file
block/blk-mq.c	modified	+7	−11	View file
block/blk-sysfs.c	modified	+9	−2	View file
drivers/target/target_core_tpg.c	modified	+2	−1	View file
fs/aio.c	modified	+2	−2	View file
fs/btrfs/disk-io.c	modified	+4	−4	View file
fs/btrfs/extent-tree.c	modified	+1	−1	View file
fs/ext2/super.c	modified	+3	−3	View file
fs/ext3/super.c	modified	+3	−3	View file
fs/ext4/super.c	modified	+9	−5	View file
fs/file_table.c	modified	+1	−1	View file
fs/quota/dquot.c	modified	+1	−1	View file
fs/super.c	modified	+2	−1	View file
include/linux/blk-mq.h	modified	+1	−0	View file
include/linux/flex_proportions.h	modified	+3	−2	View file
include/linux/percpu-refcount.h	modified	+80	−42	View file
include/linux/percpu.h	modified	+9	−4	View file
include/linux/percpu_counter.h	modified	+6	−4	View file
include/linux/proportions.h	modified	+3	−2	View file
include/net/dst_ops.h	modified	+1	−1	View file
include/net/inet_frag.h	modified	+1	−1	View file
kernel/cgroup.c	modified	+4	−3	View file
lib/flex_proportions.c	modified	+4	−4	View file
lib/percpu-refcount.c	modified	+217	−88	View file
lib/percpu_counter.c	modified	+12	−8	View file
lib/proportions.c	modified	+5	−5	View file
mm/backing-dev.c	modified	+2	−2	View file
mm/mmap.c	modified	+1	−1	View file
mm/nommu.c	modified	+1	−1	View file
mm/page-writeback.c	modified	+1	−1	View file
mm/percpu-km.c	modified	+9	−7	View file
mm/percpu-vm.c	modified	+35	−127	View file
mm/percpu.c	modified	+427	−99	View file
mm/shmem.c	modified	+1	−1	View file
net/dccp/proto.c	modified	+1	−1	View file
net/ipv4/tcp.c	modified	+2	−2	View file
net/ipv4/tcp_memcontrol.c	modified	+1	−1	View file
net/sctp/protocol.c	modified	+1	−1	View file

Only the first 600 diff lines are shown. Download the complete patch.

arch/x86/kvm/mmu.c

View file

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3201e93..ac1c4de 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4549,7 +4549,7 @@ int kvm_mmu_module_init(void)
 	if (!mmu_page_header_cache)
 		goto nomem;
 
-	if (percpu_counter_init(&kvm_total_used_mmu_pages, 0))
+	if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL))
 		goto nomem;
 
 	register_shrinker(&mmu_shrinker);

block/blk-mq-sysfs.c

View file

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index ed52178..371d880 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -402,6 +402,12 @@ static void blk_mq_sysfs_init(struct request_queue *q)
 	}
 }
 
+/* see blk_register_queue() */
+void blk_mq_finish_init(struct request_queue *q)
+{
+	percpu_ref_switch_to_percpu(&q->mq_usage_counter);
+}
+
 int blk_mq_register_disk(struct gendisk *disk)
 {
 	struct device *dev = disk_to_dev(disk);

block/blk-mq.c

View file

diff --git a/block/blk-mq.c b/block/blk-mq.c
index df8e1e0..38f4a16 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -119,16 +119,7 @@ void blk_mq_freeze_queue(struct request_queue *q)
 	spin_unlock_irq(q->queue_lock);
 
 	if (freeze) {
-		/*
-		 * XXX: Temporary kludge to work around SCSI blk-mq stall.
-		 * SCSI synchronously creates and destroys many queues
-		 * back-to-back during probe leading to lengthy stalls.
-		 * This will be fixed by keeping ->mq_usage_counter in
-		 * atomic mode until genhd registration, but, for now,
-		 * let's work around using expedited synchronization.
-		 */
-		__percpu_ref_kill_expedited(&q->mq_usage_counter);
-
+		percpu_ref_kill(&q->mq_usage_counter);
 		blk_mq_run_queues(q, false);
 	}
 	wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
@@ -1804,7 +1795,12 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 	if (!q)
 		goto err_hctxs;
 
-	if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release))
+	/*
+	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
+	 * See blk_register_queue() for details.
+	 */
+	if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
+			    PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
 		goto err_map;
 
 	setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);

block/blk-sysfs.c

View file

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 17f5c84..521ae90 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -551,12 +551,19 @@ int blk_register_queue(struct gendisk *disk)
 		return -ENXIO;
 
 	/*
-	 * Initialization must be complete by now.  Finish the initial
-	 * bypass from queue allocation.
+	 * SCSI probing may synchronously create and destroy a lot of
+	 * request_queues for non-existent devices.  Shutting down a fully
+	 * functional queue takes measureable wallclock time as RCU grace
+	 * periods are involved.  To avoid excessive latency in these
+	 * cases, a request_queue starts out in a degraded mode which is
+	 * faster to shut down and is made fully functional here as
+	 * request_queues for non-existent devices never get registered.
 	 */
 	if (!blk_queue_init_done(q)) {
 		queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
 		blk_queue_bypass_end(q);
+		if (q->mq_ops)
+			blk_mq_finish_init(q);
 	}
 
 	ret = blk_trace_init_sysfs(dev);

drivers/target/target_core_tpg.c

View file

diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index fddfae6..be783f7 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -819,7 +819,8 @@ int core_tpg_add_lun(
 {
 	int ret;
 
-	ret = percpu_ref_init(&lun->lun_ref, core_tpg_lun_ref_release);
+	ret = percpu_ref_init(&lun->lun_ref, core_tpg_lun_ref_release, 0,
+			      GFP_KERNEL);
 	if (ret < 0)
 		return ret;
 

fs/aio.c

View file

diff --git a/fs/aio.c b/fs/aio.c
index 7337500..84a7510 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -661,10 +661,10 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 
 	INIT_LIST_HEAD(&ctx->active_reqs);
 
-	if (percpu_ref_init(&ctx->users, free_ioctx_users))
+	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
 		goto err;
 
-	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs))
+	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
 		goto err;
 
 	ctx->cpu = alloc_percpu(struct kioctx_cpu);

fs/btrfs/disk-io.c

View file

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a1d36e6..d0d78dc 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1183,7 +1183,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)
 	if (!writers)
 		return ERR_PTR(-ENOMEM);
 
-	ret = percpu_counter_init(&writers->counter, 0);
+	ret = percpu_counter_init(&writers->counter, 0, GFP_KERNEL);
 	if (ret < 0) {
 		kfree(writers);
 		return ERR_PTR(ret);
@@ -2188,7 +2188,7 @@ int open_ctree(struct super_block *sb,
 		goto fail_srcu;
 	}
 
-	ret = percpu_counter_init(&fs_info->dirty_metadata_bytes, 0);
+	ret = percpu_counter_init(&fs_info->dirty_metadata_bytes, 0, GFP_KERNEL);
 	if (ret) {
 		err = ret;
 		goto fail_bdi;
@@ -2196,13 +2196,13 @@ int open_ctree(struct super_block *sb,
 	fs_info->dirty_metadata_batch = PAGE_CACHE_SIZE *
 					(1 + ilog2(nr_cpu_ids));
 
-	ret = percpu_counter_init(&fs_info->delalloc_bytes, 0);
+	ret = percpu_counter_init(&fs_info->delalloc_bytes, 0, GFP_KERNEL);
 	if (ret) {
 		err = ret;
 		goto fail_dirty_metadata_bytes;
 	}
 
-	ret = percpu_counter_init(&fs_info->bio_counter, 0);
+	ret = percpu_counter_init(&fs_info->bio_counter, 0, GFP_KERNEL);
 	if (ret) {
 		err = ret;
 		goto fail_delalloc_bytes;

fs/btrfs/extent-tree.c

View file

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3efe1c3..caaf015 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3494,7 +3494,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
 	if (!found)
 		return -ENOMEM;
 
-	ret = percpu_counter_init(&found->total_bytes_pinned, 0);
+	ret = percpu_counter_init(&found->total_bytes_pinned, 0, GFP_KERNEL);
 	if (ret) {
 		kfree(found);
 		return ret;

fs/ext2/super.c

View file

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index b88edc0..170dc41 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1067,14 +1067,14 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);
 
 	err = percpu_counter_init(&sbi->s_freeblocks_counter,
-				ext2_count_free_blocks(sb));
+				ext2_count_free_blocks(sb), GFP_KERNEL);
 	if (!err) {
 		err = percpu_counter_init(&sbi->s_freeinodes_counter,
-				ext2_count_free_inodes(sb));
+				ext2_count_free_inodes(sb), GFP_KERNEL);
 	}
 	if (!err) {
 		err = percpu_counter_init(&sbi->s_dirs_counter,
-				ext2_count_dirs(sb));
+				ext2_count_dirs(sb), GFP_KERNEL);
 	}
 	if (err) {
 		ext2_msg(sb, KERN_ERR, "error: insufficient memory");

fs/ext3/super.c

View file

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 622e882..bb0fdac 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2039,14 +2039,14 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 		goto failed_mount2;
 	}
 	err = percpu_counter_init(&sbi->s_freeblocks_counter,
-			ext3_count_free_blocks(sb));
+			ext3_count_free_blocks(sb), GFP_KERNEL);
 	if (!err) {
 		err = percpu_counter_init(&sbi->s_freeinodes_counter,
-				ext3_count_free_inodes(sb));
+				ext3_count_free_inodes(sb), GFP_KERNEL);
 	}
 	if (!err) {
 		err = percpu_counter_init(&sbi->s_dirs_counter,
-				ext3_count_dirs(sb));
+				ext3_count_dirs(sb), GFP_KERNEL);
 	}
 	if (err) {
 		ext3_msg(sb, KERN_ERR, "error: insufficient memory");

fs/ext4/super.c

View file

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0b28b36..05c1592 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3892,7 +3892,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	/* Register extent status tree shrinker */
 	ext4_es_register_shrinker(sbi);
 
-	if ((err = percpu_counter_init(&sbi->s_extent_cache_cnt, 0)) != 0) {
+	err = percpu_counter_init(&sbi->s_extent_cache_cnt, 0, GFP_KERNEL);
+	if (err) {
 		ext4_msg(sb, KERN_ERR, "insufficient memory");
 		goto failed_mount3;
 	}
@@ -4106,17 +4107,20 @@ no_journal:
 	block = ext4_count_free_clusters(sb);
 	ext4_free_blocks_count_set(sbi->s_es, 
 				   EXT4_C2B(sbi, block));
-	err = percpu_counter_init(&sbi->s_freeclusters_counter, block);
+	err = percpu_counter_init(&sbi->s_freeclusters_counter, block,
+				  GFP_KERNEL);
 	if (!err) {
 		unsigned long freei = ext4_count_free_inodes(sb);
 		sbi->s_es->s_free_inodes_count = cpu_to_le32(freei);
-		err = percpu_counter_init(&sbi->s_freeinodes_counter, freei);
+		err = percpu_counter_init(&sbi->s_freeinodes_counter, freei,
+					  GFP_KERNEL);
 	}
 	if (!err)
 		err = percpu_counter_init(&sbi->s_dirs_counter,
-					  ext4_count_dirs(sb));
+					  ext4_count_dirs(sb), GFP_KERNEL);
 	if (!err)
-		err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0);
+		err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0,
+					  GFP_KERNEL);
 	if (err) {
 		ext4_msg(sb, KERN_ERR, "insufficient memory");
 		goto failed_mount6;

fs/file_table.c

View file

diff --git a/fs/file_table.c b/fs/file_table.c
index 385bfd3..0bab12b 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -331,5 +331,5 @@ void __init files_init(unsigned long mempages)
 
 	n = (mempages * (PAGE_SIZE / 1024)) / 10;
 	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
-	percpu_counter_init(&nr_files, 0);
+	percpu_counter_init(&nr_files, 0, GFP_KERNEL);
 } 

fs/quota/dquot.c

View file

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index f2d0eee..8b663b2 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2725,7 +2725,7 @@ static int __init dquot_init(void)
 		panic("Cannot create dquot hash table");
 
 	for (i = 0; i < _DQST_DQSTAT_LAST; i++) {
-		ret = percpu_counter_init(&dqstats.counter[i], 0);
+		ret = percpu_counter_init(&dqstats.counter[i], 0, GFP_KERNEL);
 		if (ret)
 			panic("Cannot create dquot stat counters");
 	}

fs/super.c

View file

diff --git a/fs/super.c b/fs/super.c
index b9a214d..1b83610 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -175,7 +175,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
 		goto fail;
 
 	for (i = 0; i < SB_FREEZE_LEVELS; i++) {
-		if (percpu_counter_init(&s->s_writers.counter[i], 0) < 0)
+		if (percpu_counter_init(&s->s_writers.counter[i], 0,
+					GFP_KERNEL) < 0)
 			goto fail;
 		lockdep_init_map(&s->s_writers.lock_map[i], sb_writers_name[i],
 				 &type->s_writers_key[i], 0);

include/linux/blk-mq.h

View file

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index a1e31f2..c13a0c0 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -140,6 +140,7 @@ enum {
 };
 
 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *);
+void blk_mq_finish_init(struct request_queue *q);
 int blk_mq_register_disk(struct gendisk *);
 void blk_mq_unregister_disk(struct gendisk *);
 

include/linux/flex_proportions.h

View file

diff --git a/include/linux/flex_proportions.h b/include/linux/flex_proportions.h
index 4ebc49f..0d348e0 100644
--- a/include/linux/flex_proportions.h
+++ b/include/linux/flex_proportions.h
@@ -10,6 +10,7 @@
 #include <linux/percpu_counter.h>
 #include <linux/spinlock.h>
 #include <linux/seqlock.h>
+#include <linux/gfp.h>
 
 /*
  * When maximum proportion of some event type is specified, this is the
@@ -32,7 +33,7 @@ struct fprop_global {
 	seqcount_t sequence;
 };
 
-int fprop_global_init(struct fprop_global *p);
+int fprop_global_init(struct fprop_global *p, gfp_t gfp);
 void fprop_global_destroy(struct fprop_global *p);
 bool fprop_new_period(struct fprop_global *p, int periods);
 
@@ -79,7 +80,7 @@ struct fprop_local_percpu {
 	raw_spinlock_t lock;	/* Protect period and numerator */
 };
 
-int fprop_local_init_percpu(struct fprop_local_percpu *pl);
+int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
 void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
 void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
 void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,

include/linux/percpu-refcount.h

View file

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 68a64f1..d5c89e0 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -13,7 +13,7 @@
  *
  * The refcount will have a range of 0 to ((1U << 31) - 1), i.e. one bit less
  * than an atomic_t - this is because of the way shutdown works, see
- * percpu_ref_kill()/PCPU_COUNT_BIAS.
+ * percpu_ref_kill()/PERCPU_COUNT_BIAS.
  *
  * Before you call percpu_ref_kill(), percpu_ref_put() does not check for the
  * refcount hitting 0 - it can't, if it was in percpu mode. percpu_ref_kill()
@@ -49,29 +49,60 @@
 #include <linux/kernel.h>
 #include <linux/percpu.h>
 #include <linux/rcupdate.h>
+#include <linux/gfp.h>
 
 struct percpu_ref;
 typedef void (percpu_ref_func_t)(struct percpu_ref *);
 
+/* flags set in the lower bits of percpu_ref->percpu_count_ptr */
+enum {
+	__PERCPU_REF_ATOMIC	= 1LU << 0,	/* operating in atomic mode */
+	__PERCPU_REF_DEAD	= 1LU << 1,	/* (being) killed */
+	__PERCPU_REF_ATOMIC_DEAD = __PERCPU_REF_ATOMIC | __PERCPU_REF_DEAD,
+
+	__PERCPU_REF_FLAG_BITS	= 2,
+};
+
+/* @flags for percpu_ref_init() */
+enum {
+	/*
+	 * Start w/ ref == 1 in atomic mode.  Can be switched to percpu
+	 * operation using percpu_ref_switch_to_percpu().  If initialized
+	 * with this flag, the ref will stay in atomic mode until
+	 * percpu_ref_switch_to_percpu() is invoked on it.
+	 */
+	PERCPU_REF_INIT_ATOMIC	= 1 << 0,
+
+	/*
+	 * Start dead w/ ref == 0 in atomic mode.  Must be revived with
+	 * percpu_ref_reinit() before used.  Implies INIT_ATOMIC.
+	 */
+	PERCPU_REF_INIT_DEAD	= 1 << 1,
+};
+
 struct percpu_ref {
-	atomic_t		count;
+	atomic_long_t		count;
 	/*
 	 * The low bit of the pointer indicates whether the ref is in percpu
 	 * mode; if set, then get/put will manipulate the atomic_t.
 	 */
-	unsigned long		pcpu_count_ptr;
+	unsigned long		percpu_count_ptr;
 	percpu_ref_func_t	*release;
-	percpu_ref_func_t	*confirm_kill;
+	percpu_ref_func_t	*confirm_switch;
+	bool			force_atomic:1;
 	struct rcu_head		rcu;
 };
 
 int __must_check percpu_ref_init(struct percpu_ref *ref,
-				 percpu_ref_func_t *release);
-void percpu_ref_reinit(struct percpu_ref *ref);
+				 percpu_ref_func_t *release, unsigned int flags,
+				 gfp_t gfp);
 void percpu_ref_exit(struct percpu_ref *ref);
+void percpu_ref_switch_to_atomic(struct percpu_ref *ref,
+				 percpu_ref_func_t *confirm_switch);
+void percpu_ref_switch_to_percpu(struct percpu_ref *ref);
 void percpu_ref_kill_and_confirm(struct percpu_ref *ref,
 				 percpu_ref_func_t *confirm_kill);
-void __percpu_ref_kill_expedited(struct percpu_ref *ref);
+void percpu_ref_reinit(struct percpu_ref *ref);
 
 /**
  * percpu_ref_kill - drop the initial ref
@@ -88,26 +119,24 @@ static inline void percpu_ref_kill(struct percpu_ref *ref)
 	return percpu_ref_kill_and_confirm(ref, NULL);
 }
 
-#define PCPU_REF_DEAD		1
-
 /*
  * Internal helper.  Don't use outside percpu-refcount proper.  The
  * function doesn't return the pointer and let the caller test it for NULL
  * because doing so forces the compiler to generate two conditional
- * branches as it can't assume that @ref->pcpu_count is not NULL.
+ * branches as it can't assume that @ref->percpu_count is not NULL.
  */
-static inline bool __pcpu_ref_alive(struct percpu_ref *ref,
-				    unsigned __percpu **pcpu_countp)
+static inline bool __ref_is_percpu(struct percpu_ref *ref,
+					  unsigned long __percpu **percpu_countp)
 {
-	unsigned long pcpu_ptr = ACCESS_ONCE(ref->pcpu_count_ptr);
+	unsigned long percpu_ptr = ACCESS_ONCE(ref->percpu_count_ptr);
 
 	/* paired with smp_store_release() in percpu_ref_reinit() */
 	smp_read_barrier_depends();
 
-	if (unlikely(pcpu_ptr & PCPU_REF_DEAD))
+	if (unlikely(percpu_ptr & __PERCPU_REF_ATOMIC))
 		return false;
 
-	*pcpu_countp = (unsigned __percpu *)pcpu_ptr;
+	*percpu_countp = (unsigned long __percpu *)percpu_ptr;
 	return true;
 }
 
@@ -115,18 +144,20 @@ static inline bool __pcpu_ref_alive(struct percpu_ref *ref,
  * percpu_ref_get - increment a percpu refcount
  * @ref: percpu_ref to get
  *
- * Analagous to atomic_inc().
-  */
+ * Analagous to atomic_long_inc().
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
 static inline void percpu_ref_get(struct percpu_ref *ref)
 {
-	unsigned __percpu *pcpu_count;
+	unsigned long __percpu *percpu_count;
 
 	rcu_read_lock_sched();
 
-	if (__pcpu_ref_alive(ref, &pcpu_count))
-		this_cpu_inc(*pcpu_count);
+	if (__ref_is_percpu(ref, &percpu_count))
+		this_cpu_inc(*percpu_count);
 	else
-		atomic_inc(&ref->count);
+		atomic_long_inc(&ref->count);
 
 	rcu_read_unlock_sched();
 }
@@ -138,20 +169,20 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
  * Increment a percpu refcount unless its count already reached zero.
  * Returns %true on success; %false on failure.
  *
- * The caller is responsible for ensuring that @ref stays accessible.
+ * This function is safe to call as long as @ref is between init and exit.
  */
 static inline bool percpu_ref_tryget(struct percpu_ref *ref)
 {
-	unsigned __percpu *pcpu_count;
-	int ret = false;
+	unsigned long __percpu *percpu_count;
+	int ret;
 
 	rcu_read_lock_sched();
 
-	if (__pcpu_ref_alive(ref, &pcpu_count)) {
-		this_cpu_inc(*pcpu_count);
+	if (__ref_is_percpu(ref, &percpu_count)) {
+		this_cpu_inc(*percpu_count);
 		ret = true;
 	} else {
-		ret = atomic_inc_not_zero(&ref->count);
+		ret = atomic_long_inc_not_zero(&ref->count);
 	}
 
 	rcu_read_unlock_sched();
@@ -166,23 +197,26 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
  * Increment a percpu refcount unless it has already been killed.  Returns
  * %true on success; %false on failure.
  *
- * Completion of percpu_ref_kill() in itself doesn't guarantee that tryget
- * will fail.  For such guarantee, percpu_ref_kill_and_confirm() should be
- * used.  After the confirm_kill callback is invoked, it's guaranteed that
- * no new reference will be given out by percpu_ref_tryget().
+ * Completion of percpu_ref_kill() in itself doesn't guarantee that this
+ * function will fail.  For such guarantee, percpu_ref_kill_and_confirm()
+ * should be used.  After the confirm_kill callback is invoked, it's
+ * guaranteed that no new reference will be given out by
+ * percpu_ref_tryget_live().
  *
- * The caller is responsible for ensuring that @ref stays accessible.
+ * This function is safe to call as long as @ref is between init and exit.
  */
 static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
 {
-	unsigned __percpu *pcpu_count;
+	unsigned long __percpu *percpu_count;
 	int ret = false;
 
 	rcu_read_lock_sched();
 
-	if (__pcpu_ref_alive(ref, &pcpu_count)) {
-		this_cpu_inc(*pcpu_count);
+	if (__ref_is_percpu(ref, &percpu_count)) {
+		this_cpu_inc(*percpu_count);
 		ret = true;
+	} else if (!(ACCESS_ONCE(ref->percpu_count_ptr) & __PERCPU_REF_DEAD)) {
+		ret = atomic_long_inc_not_zero(&ref->count);
 	}
 
 	rcu_read_unlock_sched();
@@ -196,16 +230,18 @@ static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
  *
  * Decrement the refcount, and if 0, call the release function (which was passed
  * to percpu_ref_init())
+ *
+ * This function is safe to call as long as @ref is between init and exit.
  */
 static inline void percpu_ref_put(struct percpu_ref *ref)
 {
-	unsigned __percpu *pcpu_count;
+	unsigned long __percpu *percpu_count;
 
 	rcu_read_lock_sched();
 
-	if (__pcpu_ref_alive(ref, &pcpu_count))
-		this_cpu_dec(*pcpu_count);
-	else if (unlikely(atomic_dec_and_test(&ref->count)))
+	if (__ref_is_percpu(ref, &percpu_count))
+		this_cpu_dec(*percpu_count);
+	else if (unlikely(atomic_long_dec_and_test(&ref->count)))
 		ref->release(ref);
 
 	rcu_read_unlock_sched();
@@ -216,14 +252,16 @@ static inline void percpu_ref_put(struct percpu_ref *ref)
  * @ref: percpu_ref to test
  *
  * Returns %true if @ref reached zero.
+ *
+ * This function is safe to call as long as @ref is between init and exit.
  */
 static inline bool percpu_ref_is_zero(struct percpu_ref *ref)
 {
-	unsigned __percpu *pcpu_count;
+	unsigned long __percpu *percpu_count;
 
-	if (__pcpu_ref_alive(ref, &pcpu_count))
+	if (__ref_is_percpu(ref, &percpu_count))
 		return false;
-	return !atomic_read(&ref->count);
+	return !atomic_long_read(&ref->count);
 }
 
 #endif

include/linux/percpu.h

View file

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 6f61b61..a3aa63e 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -48,9 +48,9 @@
  * intelligent way to determine this would be nice.
  */
 #if BITS_PER_LONG > 32
-#define PERCPU_DYNAMIC_RESERVE		(20 << 10)
+#define PERCPU_DYNAMIC_RESERVE		(28 << 10)
 #else
-#define PERCPU_DYNAMIC_RESERVE		(12 << 10)
+#define PERCPU_DYNAMIC_RESERVE		(20 << 10)
 #endif
 
 extern void *pcpu_base_addr;
@@ -122,11 +122,16 @@ extern void __init setup_per_cpu_areas(void);
 #endif