[dpdk-dev] [PATCH 5/6] net/bnx2x: fix race for periodic flags

[Rasesh Mody <rmody@marvell.com>]

The periodic callout function and the interrupt handler both modify the
periodic flags. There is a possible race condition when an application is
going through dev_stop()/dev_start() and an interrupt handler is invoked.
We also need to ensure that periodic polling is not invoked in interrupt
context.

This patch handles such case by using separate variable to check for
interrupt context. Also, atomically load and store the periodic flag
value.

Fixes: 0f6ebeee2402 ("net/bnx2x: fix call to link handling periodic function")
Cc: stable@dpdk.org

Signed-off-by: Rasesh Mody <rmody@marvell.com>
---
 drivers/net/bnx2x/bnx2x_ethdev.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/net/bnx2x/bnx2x_ethdev.c b/drivers/net/bnx2x/bnx2x_ethdev.c
index f85766c..3063aea 100644
--- a/drivers/net/bnx2x/bnx2x_ethdev.c
+++ b/drivers/net/bnx2x/bnx2x_ethdev.c
@@ -108,14 +108,15 @@ struct rte_bnx2x_xstats_name_off {
 }
 
 static void
-bnx2x_interrupt_action(struct rte_eth_dev *dev)
+bnx2x_interrupt_action(struct rte_eth_dev *dev, int intr_cxt)
 {
 	struct bnx2x_softc *sc = dev->data->dev_private;
 	uint32_t link_status;
 
 	bnx2x_intr_legacy(sc);
 
-	if (sc->periodic_flags & PERIODIC_GO)
+	if ((atomic_load_acq_long(&sc->periodic_flags) == PERIODIC_GO) &&
+	    !intr_cxt)
 		bnx2x_periodic_callout(sc);
 	link_status = REG_RD(sc, sc->link_params.shmem_base +
 			offsetof(struct shmem_region,
@@ -132,9 +133,7 @@ struct rte_bnx2x_xstats_name_off {
 
 	PMD_DEBUG_PERIODIC_LOG(INFO, sc, "Interrupt handled");
 
-	atomic_store_rel_long(&sc->periodic_flags, PERIODIC_STOP);
-	bnx2x_interrupt_action(dev);
-	atomic_store_rel_long(&sc->periodic_flags, PERIODIC_GO);
+	bnx2x_interrupt_action(dev, 1);
 	rte_intr_enable(&sc->pci_dev->intr_handle);
 }
 
@@ -145,7 +144,7 @@ static void bnx2x_periodic_start(void *param)
 	int ret = 0;
 
 	atomic_store_rel_long(&sc->periodic_flags, PERIODIC_GO);
-	bnx2x_interrupt_action(dev);
+	bnx2x_interrupt_action(dev, 0);
 	if (IS_PF(sc)) {
 		ret = rte_eal_alarm_set(BNX2X_SP_TIMER_PERIOD,
 					bnx2x_periodic_start, (void *)dev);
@@ -165,6 +164,8 @@ void bnx2x_periodic_stop(void *param)
 	atomic_store_rel_long(&sc->periodic_flags, PERIODIC_STOP);
 
 	rte_eal_alarm_cancel(bnx2x_periodic_start, (void *)dev);
+
+	PMD_DRV_LOG(DEBUG, sc, "Periodic poll stopped");
 }
 
 /*
@@ -226,8 +227,10 @@ void bnx2x_periodic_stop(void *param)
 	PMD_INIT_FUNC_TRACE(sc);
 
 	/* start the periodic callout */
-	if (sc->periodic_flags & PERIODIC_STOP)
+	if (atomic_load_acq_long(&sc->periodic_flags) == PERIODIC_STOP) {
 		bnx2x_periodic_start(dev);
+		PMD_DRV_LOG(DEBUG, sc, "Periodic poll re-started");
+	}
 
 	ret = bnx2x_init(sc);
 	if (ret) {
-- 
1.7.10.3