netdev - [PATCH net-next] liquidio: fix race condition in instruction completion processing

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Message-ID: <20180828183255.GA7536@felix-thinkpad.cavium.com>
Date:   Tue, 28 Aug 2018 11:32:55 -0700
From:   Felix Manlunas <felix.manlunas@...ium.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, raghu.vatsavayi@...ium.com,
        derek.chickles@...ium.com, satananda.burla@...ium.com,
        felix.manlunas@...ium.com, ricardo.farrington@...ium.com
Subject: [PATCH net-next] liquidio: fix race condition in instruction
 completion processing

From: Rick Farrington <ricardo.farrington@...ium.com>

In lio_enable_irq, the pkt_in_done count register was being cleared to
zero.  However, there could be some completed instructions which were not
yet processed due to budget and limit constraints.
So, only write this register with the number of actual completions
that were processed.

Signed-off-by: Rick Farrington <ricardo.farrington@...ium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@...ium.com>
---
 drivers/net/ethernet/cavium/liquidio/octeon_device.c   | 5 +++--
 drivers/net/ethernet/cavium/liquidio/octeon_iq.h       | 2 ++
 drivers/net/ethernet/cavium/liquidio/request_manager.c | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/octeon_device.c b/drivers/net/ethernet/cavium/liquidio/octeon_device.c
index f878a55..d0ed6c4 100644
--- a/drivers/net/ethernet/cavium/liquidio/octeon_device.c
+++ b/drivers/net/ethernet/cavium/liquidio/octeon_device.c
@@ -1450,8 +1450,9 @@ void lio_enable_irq(struct octeon_droq *droq, struct octeon_instr_queue *iq)
 	}
 	if (iq) {
 		spin_lock_bh(&iq->lock);
-		writel(iq->pkt_in_done, iq->inst_cnt_reg);
-		iq->pkt_in_done = 0;
+		writel(iq->pkts_processed, iq->inst_cnt_reg);
+		iq->pkt_in_done -= iq->pkts_processed;
+		iq->pkts_processed = 0;
 		/* this write needs to be flushed before we release the lock */
 		mmiowb();
 		spin_unlock_bh(&iq->lock);
diff --git a/drivers/net/ethernet/cavium/liquidio/octeon_iq.h b/drivers/net/ethernet/cavium/liquidio/octeon_iq.h
index 2327062..aecd0d3 100644
--- a/drivers/net/ethernet/cavium/liquidio/octeon_iq.h
+++ b/drivers/net/ethernet/cavium/liquidio/octeon_iq.h
@@ -94,6 +94,8 @@ struct octeon_instr_queue {
 
 	u32 pkt_in_done;
 
+	u32 pkts_processed;
+
 	/** A spinlock to protect access to the input ring.*/
 	spinlock_t iq_flush_running_lock;
 
diff --git a/drivers/net/ethernet/cavium/liquidio/request_manager.c b/drivers/net/ethernet/cavium/liquidio/request_manager.c
index 8f746e1..f943aa7 100644
--- a/drivers/net/ethernet/cavium/liquidio/request_manager.c
+++ b/drivers/net/ethernet/cavium/liquidio/request_manager.c
@@ -123,6 +123,7 @@ int octeon_init_instr_queue(struct octeon_device *oct,
 	iq->do_auto_flush = 1;
 	iq->db_timeout = (u32)conf->db_timeout;
 	atomic_set(&iq->instr_pending, 0);
+	iq->pkts_processed = 0;
 
 	/* Initialize the spinlock for this instruction queue */
 	spin_lock_init(&iq->lock);
@@ -495,6 +496,7 @@ static inline void __copy_cmd_into_iq(struct octeon_instr_queue *iq,
 				lio_process_iq_request_list(oct, iq, 0);
 
 		if (inst_processed) {
+			iq->pkts_processed += inst_processed;
 			atomic_sub(inst_processed, &iq->instr_pending);
 			iq->stats.instr_processed += inst_processed;
 		}
-- 
1.8.3.1