linux-kernel - [PATCH] refcount: restore kref_get and kref

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Message-Id: <20170308092549.28982-2-jhubbard@nvidia.com>
Date:   Wed,  8 Mar 2017 01:25:49 -0800
From:   john.hubbard@...il.com
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        John Hubbard <jhubbard@...dia.com>
Subject: [PATCH] refcount: restore kref_get and kref_put to non-GPL status

From: John Hubbard <jhubbard@...dia.com>

Originally, kref_get and kref_put were available as
standard routines that even non-GPL device drivers
could use. However, as an unintended side effect of
the recent kref_*() upgrade[1], these calls are now
effectively GPL, because they get routed to the
new refcount_inc() and refcount_dec_and_test()
routines.

Make just those routines non-GPL, in order to restore
the original behavior--and to avoid forcing simple
users of krefs to re-implement atomic refcounting.

[1] commit 10383aea2f44 ("kref: Implement 'struct kref' using refcount_t")

Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
 lib/refcount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/refcount.c b/lib/refcount.c
index aa09ad3c30b0..6421a4930484 100644
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -113,7 +113,7 @@ void refcount_inc(refcount_t *r)
 {
 	WARN_ONCE(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n");
 }
-EXPORT_SYMBOL_GPL(refcount_inc);
+EXPORT_SYMBOL(refcount_inc);
 
 bool refcount_sub_and_test(unsigned int i, refcount_t *r)
 {
@@ -152,7 +152,7 @@ bool refcount_dec_and_test(refcount_t *r)
 {
 	return refcount_sub_and_test(1, r);
 }
-EXPORT_SYMBOL_GPL(refcount_dec_and_test);
+EXPORT_SYMBOL(refcount_dec_and_test);
 
 /*
  * Similar to atomic_dec(), it will WARN on underflow and fail to decrement
-- 
2.12.0