Commit 858430db authored by Sean Anderson's avatar Sean Anderson Committed by Jakub Kicinski
Browse files

net: xilinx: axienet: Fix race in axienet_stop 



axienet_dma_err_handler can race with axienet_stop in the following
manner:

CPU 1                       CPU 2
======================      ==================
axienet_stop()
    napi_disable()
    axienet_dma_stop()
                            axienet_dma_err_handler()
                                napi_disable()
                                axienet_dma_stop()
                                axienet_dma_start()
                                napi_enable()
    cancel_work_sync()
    free_irq()

Fix this by setting a flag in axienet_stop telling
axienet_dma_err_handler not to bother doing anything. I chose not to use
disable_work_sync to allow for easier backporting.

Signed-off-by: default avatarSean Anderson <sean.anderson@linux.dev>
Fixes: 8a3b7a25 ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Link: https://patch.msgid.link/20240903175141.4132898-1-sean.anderson@linux.dev


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent bee2ef94

drivers/net/ethernet/xilinx/xilinx_axienet.h

+3 −0
Original line number Diff line number Diff line
@@ -436,6 +436,8 @@ struct skbuf_dma_descriptor { 
 * @tx_bytes:	TX byte count for statistics

 * @tx_stat_sync: Synchronization object for TX stats

 * @dma_err_task: Work structure to process Axi DMA errors

 * @stopping:   Set when @dma_err_task shouldn't do anything because we are

 *              about to stop the device.

 * @tx_irq:	Axidma TX IRQ number

 * @rx_irq:	Axidma RX IRQ number

 * @eth_irq:	Ethernet core IRQ number
@@ -507,6 +509,7 @@ struct axienet_local { 
	struct u64_stats_sync tx_stat_sync;



	struct work_struct dma_err_task;

	bool stopping;



	int tx_irq;

	int rx_irq;

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

+8 −0
Original line number Diff line number Diff line
@@ -1460,6 +1460,7 @@ static int axienet_init_legacy_dma(struct net_device *ndev) 
	struct axienet_local *lp = netdev_priv(ndev);



	/* Enable worker thread for Axi DMA error handling */

	lp->stopping = false;

	INIT_WORK(&lp->dma_err_task, axienet_dma_err_handler);



	napi_enable(&lp->napi_rx);
@@ -1580,6 +1581,9 @@ static int axienet_stop(struct net_device *ndev) 
	dev_dbg(&ndev->dev, "axienet_close()\n");



	if (!lp->use_dmaengine) {

		WRITE_ONCE(lp->stopping, true);

		flush_work(&lp->dma_err_task);



		napi_disable(&lp->napi_tx);

		napi_disable(&lp->napi_rx);

	}
@@ -2154,6 +2158,10 @@ static void axienet_dma_err_handler(struct work_struct *work) 
						dma_err_task);

	struct net_device *ndev = lp->ndev;



	/* Don't bother if we are going to stop anyway */

	if (READ_ONCE(lp->stopping))

		return;



	napi_disable(&lp->napi_tx);

	napi_disable(&lp->napi_rx);