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net: xilinx: axienet: Fix race in axienet_stop

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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: Sean Anderson <sean.anderson@linux.dev>
Fixes: 8a3b7a252d ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Link: https://patch.msgid.link/20240903175141.4132898-1-sean.anderson@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Sean Anderson 2024-09-03 13:51:41 -04:00 committed by Jakub Kicinski
parent bee2ef946d
commit 858430db28
2 changed files with 11 additions and 0 deletions
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3
drivers/net/ethernet/xilinx/xilinx_axienet.h
View File

@ -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;

8
drivers/net/ethernet/xilinx/xilinx_axienet_main.c
View File

@ -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);