From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 28 Jun 2018 06:26:01 +0000 (-0700)
Subject: lib/percpu_ida.c: don't do alloc from per-CPU list if there is none
X-Git-Tag: Ubuntu-5.2.0-15.16~4095^2~6
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=4bb6e96ab808f88d746343637f0cc2243b527da5;p=mirror_ubuntu-eoan-kernel.git

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 9bbd9c5d375a..beb14839b41a 100644
--- 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;