2019-08-06 02:59:49

by Chuhong Yuan

Subject: [PATCH 1/2] cxgb4: smt: Add lock for atomic_dec_and_test

The atomic_dec_and_test() is not safe because it is
outside of locks.
Move the locks of t4_smte_free() to its caller,
cxgb4_smt_release() to protect the atomic decrement.

Fixes: 3bdb376e6944 ("cxgb4: introduce SMT ops to prepare for SMAC rewrite support")
Signed-off-by: Chuhong Yuan <[email protected]>
---
drivers/net/ethernet/chelsio/cxgb4/smt.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/smt.c b/drivers/net/ethernet/chelsio/cxgb4/smt.c
index eaf1fb74689c..d6e84c8b5554 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/smt.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/smt.c
@@ -97,11 +97,9 @@ static struct smt_entry *find_or_alloc_smte(struct smt_data *s, u8 *smac)

static void t4_smte_free(struct smt_entry *e)
{
- spin_lock_bh(&e->lock);
if (atomic_read(&e->refcnt) == 0) { /* hasn't been recycled */
e->state = SMT_STATE_UNUSED;
}
- spin_unlock_bh(&e->lock);
}

/**
@@ -111,8 +109,10 @@ static void t4_smte_free(struct smt_entry *e)
*/
void cxgb4_smt_release(struct smt_entry *e)
{
+ spin_lock_bh(&e->lock);
if (atomic_dec_and_test(&e->refcnt))
t4_smte_free(e);
+ spin_unlock_bh(&e->lock);
}
EXPORT_SYMBOL(cxgb4_smt_release);

--
2.20.1

2019-08-09 01:13:29

by David Miller

Subject: Re: [PATCH 1/2] cxgb4: smt: Add lock for atomic_dec_and_test

From: Chuhong Yuan <[email protected]>
Date: Tue, 6 Aug 2019 10:58:46 +0800

> The atomic_dec_and_test() is not safe because it is
> outside of locks.
> Move the locks of t4_smte_free() to its caller,
> cxgb4_smt_release() to protect the atomic decrement.
>
> Fixes: 3bdb376e6944 ("cxgb4: introduce SMT ops to prepare for SMAC rewrite support")
> Signed-off-by: Chuhong Yuan <[email protected]>

Applied.