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Nit: need extra empty line between two paragraph. > On SMP systems, this can cause the done_isr and err_isr to execute > concurrently on different CPUs, leading to race conditions and > NULL pointer dereferences. On SMP systems, the race conditons and NULL pointer dereferences happen if the done_isr and err_isr to execute concurrently on different CPUs > > Fix by: > - In done_isr: abort if ERROR bit is set or DONE bit was already cleared > - In err_isr: clear both DONE and ERROR bits to prevent done_isr from > processing the same transaction > > Link: https://www.sifive.com/document-file/freedom-u540-c000-manual [1] > Link: https://www.sifive.com/document-file/freedom-u740-c000-manual [2] > Fixes: 6973886ad58e ("dmaengine: sf-pdma: add platform DMA support for HiFive Unleashed A00") > Cc: stable@vger.kernel.org > Signed-off-by: Max Hsu > --- > drivers/dma/sf-pdma/sf-pdma.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma/sf-pdma/sf-pdma.c b/drivers/dma/sf-pdma/sf-pdma.c > index 7ad3c29be146..ac7d3b127a24 100644 > --- a/drivers/dma/sf-pdma/sf-pdma.c > +++ b/drivers/dma/sf-pdma/sf-pdma.c > @@ -346,9 +346,25 @@ static irqreturn_t sf_pdma_done_isr(int irq, void *dev_id) > struct sf_pdma_chan *chan = dev_id; > struct pdma_regs *regs = &chan->regs; > u64 residue; > + u32 control_reg; > > spin_lock(&chan->vchan.lock); > - writel((readl(regs->ctrl)) & ~PDMA_DONE_STATUS_MASK, regs->ctrl); > + control_reg = readl(regs->ctrl); > + if (control_reg & PDMA_ERR_STATUS_MASK) { > + spin_unlock(&chan->vchan.lock); > + return IRQ_HANDLED; > + } > + > + /* > + * Check if DONE bit is still set. If not, the error ISR on another > + * CPU has already cleared it, so abort to avoid double-processing. > + */ > + if (!(control_reg & PDMA_DONE_STATUS_MASK)) { > + spin_unlock(&chan->vchan.lock); > + return IRQ_HANDLED; > + } > + > + writel((control_reg & ~PDMA_DONE_STATUS_MASK), regs->ctrl); > residue = readq(regs->residue); > > if (!residue) { > @@ -375,7 +391,7 @@ static irqreturn_t sf_pdma_err_isr(int irq, void *dev_id) > struct pdma_regs *regs = &chan->regs; > > spin_lock(&chan->lock); > - writel((readl(regs->ctrl)) & ~PDMA_ERR_STATUS_MASK, regs->ctrl); > + writel((readl(regs->ctrl)) & ~(PDMA_DONE_STATUS_MASK | PDMA_ERR_STATUS_MASK), regs->ctrl); > spin_unlock(&chan->lock); > > tasklet_schedule(&chan->err_tasklet); ideally, it'd better handle by one function sf_pdma_isr() { stat = readl(regs->ctrl); writel(stat & ~(PDMA_DONE_STATUS_MASK | PDMA_ERR_STATUS_MASK), regs->ctrl); if (err) return err_handle(); if (done) return done_handle(); return IRQ_NONE; } Anyways, this also work Reviewed-by: Frank Li > > -- > 2.43.0 >