On 2020/06/11 Krzysztof Kozlowski <[email protected]> wrote: > On Toradex Colibri VF50 (Vybrid VF5xx) with fsl-edma driver NULL pointer > exception happens occasionally on serial output initiated by login timeout. > > This was reproduced only if kernel was built with significant debugging > options > and EDMA driver is used with serial console. > > Issue looks like a race condition between interrupt handler > fsl_edma_tx_handler() (called as a result of fsl_edma_xfer_desc()) and > terminating the transfer with fsl_edma_terminate_all(). > > The fsl_edma_tx_handler() handles interrupt for a transfer with already freed > edesc and idle==true. > > The mcf-edma driver shares design and lot of code with fsl-edma. It looks > like > being affected by same problem. Fix this pattern the same way as fix for > fsl-edma driver. > > Fixes: e7a3ff92eaf1 ("dmaengine: fsl-edma: add ColdFire mcf5441x edma > support") > Cc: <[email protected]> > Signed-off-by: Krzysztof Kozlowski <[email protected]> Reviewed-by: Robin Gong <[email protected]> > > --- > > Not tested on HW. > --- > drivers/dma/mcf-edma.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/dma/mcf-edma.c b/drivers/dma/mcf-edma.c index > e15bd15a9ef6..e12b754e6398 100644 > --- a/drivers/dma/mcf-edma.c > +++ b/drivers/dma/mcf-edma.c > @@ -35,6 +35,13 @@ static irqreturn_t mcf_edma_tx_handler(int irq, void > *dev_id) > mcf_chan = &mcf_edma->chans[ch]; > > spin_lock(&mcf_chan->vchan.lock); > + > + if (!mcf_chan->edesc) { > + /* terminate_all called before */ > + spin_unlock(&mcf_chan->vchan.lock); > + continue; > + } > + > if (!mcf_chan->edesc->iscyclic) { > list_del(&mcf_chan->edesc->vdesc.node); > vchan_cookie_complete(&mcf_chan->edesc->vdesc); > -- > 2.7.4
