[PATCHv4 net-next 05/32] cxgb4: use spinlock_irqsave/spinlock_irqrestore for db lock

[Hariprasad Shenai]

From: Kumar Sanghvi <kuma...@chelsio.com>

Currently ring_tx_db() can deadlock if a db_full interrupt fires and is
run on the same while ring_tx_db() has the db lock held.  It needs to
disable interrupts since it serializes with an interrupt handler.

Based on original work by Steve Wise <sw...@opengridcomputing.com>

Signed-off-by: Kumar Sanghvi <kuma...@chelsio.com>
---
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c | 11 +++++++----
 drivers/net/ethernet/chelsio/cxgb4/sge.c        |  5 +++--
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c 
b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
index 0ac53dd..a95668e 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
@@ -3585,9 +3585,11 @@ static void disable_txq_db(struct sge_txq *q)
 
 static void enable_txq_db(struct sge_txq *q)
 {
-       spin_lock_irq(&q->db_lock);
+       unsigned long flags;
+
+       spin_lock_irqsave(&q->db_lock, flags);
        q->db_disabled = 0;
-       spin_unlock_irq(&q->db_lock);
+       spin_unlock_irqrestore(&q->db_lock, flags);
 }
 
 static void disable_dbs(struct adapter *adap)
@@ -3617,9 +3619,10 @@ static void enable_dbs(struct adapter *adap)
 static void sync_txq_pidx(struct adapter *adap, struct sge_txq *q)
 {
        u16 hw_pidx, hw_cidx;
+       unsigned long flags;
        int ret;
 
-       spin_lock_bh(&q->db_lock);
+       spin_lock_irqsave(&q->db_lock, flags);
        ret = read_eq_indices(adap, (u16)q->cntxt_id, &hw_pidx, &hw_cidx);
        if (ret)
                goto out;
@@ -3636,7 +3639,7 @@ static void sync_txq_pidx(struct adapter *adap, struct 
sge_txq *q)
        }
 out:
        q->db_disabled = 0;
-       spin_unlock_bh(&q->db_lock);
+       spin_unlock_irqrestore(&q->db_lock, flags);
        if (ret)
                CH_WARN(adap, "DB drop recovery failed.\n");
 }
diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c 
b/drivers/net/ethernet/chelsio/cxgb4/sge.c
index a7c56b3..c6fa96a 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c
@@ -860,9 +860,10 @@ static void cxgb_pio_copy(u64 __iomem *dst, u64 *src)
 static inline void ring_tx_db(struct adapter *adap, struct sge_txq *q, int n)
 {
        unsigned int *wr, index;
+       unsigned long flags;
 
        wmb();            /* write descriptors before telling HW */
-       spin_lock(&q->db_lock);
+       spin_lock_irqsave(&q->db_lock, flags);
        if (!q->db_disabled) {
                if (is_t4(adap->params.chip)) {
                        t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL),
@@ -880,7 +881,7 @@ static inline void ring_tx_db(struct adapter *adap, struct 
sge_txq *q, int n)
                }
        }
        q->db_pidx = q->pidx;
-       spin_unlock(&q->db_lock);
+       spin_unlock_irqrestore(&q->db_lock, flags);
 }
 
 /**
-- 
1.8.4

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