lib/percpu_ida.c: don't do alloc from per-CPU list if there is none

In commit 804209d8a009 ("lib/percpu_ida.c: use _irqsave() instead of
local_irq_save() + spin_lock") I inlined alloc_local_tag() and mixed up
the >= check from percpu_ida_alloc() with the one in alloc_local_tag().

Don't alloc from per-CPU freelist if ->nr_free is zero.

Link: http://lkml.kernel.org/r/20180613075830.c3zeva52fuj6fxxv@linutronix.de
Fixes: 804209d8a009 ("lib/percpu_ida.c: use _irqsave() instead of local_irq_save() + spin_lock")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: David Disseldorp <ddiss@suse.de>
Tested-by: David Disseldorp <ddiss@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c
index 9bbd9c5d375a2c8bf9a6d950ba42ab556c12063b..beb14839b41ae3c04fd698ec33a34727a2bc92d5 100644 (file)
--- a/lib/percpu_ida.c
+++ b/lib/percpu_ida.c
@@ -141,7 +141,7 @@ int percpu_ida_alloc(struct percpu_ida *pool, int state)
        spin_lock_irqsave(&tags->lock, flags);
 
        /* Fastpath */
-       if (likely(tags->nr_free >= 0)) {
+       if (likely(tags->nr_free)) {
                tag = tags->freelist[--tags->nr_free];
                spin_unlock_irqrestore(&tags->lock, flags);
                return tag;