On 2023-07-26 04:48, Chengfeng Ye wrote: > As plx_dma_process_desc() is invoked by both tasklet plx_dma_desc_task() > under softirq context and plx_dma_tx_status() callback that executed under > process context, the lock aquicision of &plxdev->ring_lock inside > plx_dma_process_desc() should disable irq otherwise deadlock could happen > if the irq preempts the execution of process context code while the lock > is held in process context on the same CPU. > > Possible deadlock scenario: > plx_dma_tx_status() > -> plx_dma_process_desc() > -> spin_lock(&plxdev->ring_lock) > <tasklet softirq> > -> plx_dma_desc_task() > -> plx_dma_process_desc() > -> spin_lock(&plxdev->ring_lock) (deadlock here) > > This flaw was found by an experimental static analysis tool I am developing > for irq-related deadlock. > > The tentative patch fixes the potential deadlock by spin_lock_irqsave() in > plx_dma_process_desc() to disable irq while lock is held. > > Signed-off-by: Chengfeng Ye <dg573847474@xxxxxxxxx> Makes sense. Thanks! Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> Logan
