From: Alexandre Bounine <alexandre.bounine@xxxxxxx> Subject: rapidio/tsi721: fix tasklet termination in dma channel release This patch is a modification of the patch originally proposed by Xiaotian Feng <xtfeng@xxxxxxxxx>: https://lkml.org/lkml/2012/11/5/413 This new version disables DMA channel interrupts and ensures that the tasklet wil not be scheduled again before calling tasklet_kill(). Unfortunately the updated patch was not released at that time due to planned rework of Tsi721 mport driver to use threaded interrupts (which has yet to happen). Recently the issue was reported again: https://lkml.org/lkml/2014/2/19/762. Description from the original Xiaotian's patch: "Some drivers use tasklet_disable in device remove/release process, tasklet_disable will inc tasklet->count and return. If the tasklet is not handled yet under some softirq pressure, the tasklet will be placed on the tasklet_vec, never have a chance to be excuted. This might lead to a heavy loaded ksoftirqd, wakeup with pending_softirq, but tasklet is disabled. tasklet_kill should be used in this case." This patch is applicable to kernel versions starting from v3.5. Signed-off-by: Alexandre Bounine <alexandre.bounine@xxxxxxx> Cc: Matt Porter <mporter@xxxxxxxxxxxxxxxxxxx> Cc: Xiaotian Feng <xtfeng@xxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Mike Galbraith <bitbucket@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [3.5+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/rapidio/devices/tsi721.h | 1 drivers/rapidio/devices/tsi721_dma.c | 27 ++++++++++++++++--------- 2 files changed, 19 insertions(+), 9 deletions(-) diff -puN drivers/rapidio/devices/tsi721.h~rapidio-tsi721-fix-tasklet-termination-in-dma-channel-release drivers/rapidio/devices/tsi721.h --- a/drivers/rapidio/devices/tsi721.h~rapidio-tsi721-fix-tasklet-termination-in-dma-channel-release +++ a/drivers/rapidio/devices/tsi721.h @@ -678,6 +678,7 @@ struct tsi721_bdma_chan { struct list_head free_list; dma_cookie_t completed_cookie; struct tasklet_struct tasklet; + bool active; }; #endif /* CONFIG_RAPIDIO_DMA_ENGINE */ diff -puN drivers/rapidio/devices/tsi721_dma.c~rapidio-tsi721-fix-tasklet-termination-in-dma-channel-release drivers/rapidio/devices/tsi721_dma.c --- a/drivers/rapidio/devices/tsi721_dma.c~rapidio-tsi721-fix-tasklet-termination-in-dma-channel-release +++ a/drivers/rapidio/devices/tsi721_dma.c @@ -206,8 +206,8 @@ void tsi721_bdma_handler(struct tsi721_b { /* Disable BDMA channel interrupts */ iowrite32(0, bdma_chan->regs + TSI721_DMAC_INTE); - - tasklet_schedule(&bdma_chan->tasklet); + if (bdma_chan->active) + tasklet_schedule(&bdma_chan->tasklet); } #ifdef CONFIG_PCI_MSI @@ -562,7 +562,7 @@ static int tsi721_alloc_chan_resources(s } #endif /* CONFIG_PCI_MSI */ - tasklet_enable(&bdma_chan->tasklet); + bdma_chan->active = true; tsi721_bdma_interrupt_enable(bdma_chan, 1); return bdma_chan->bd_num - 1; @@ -576,9 +576,7 @@ err_out: static void tsi721_free_chan_resources(struct dma_chan *dchan) { struct tsi721_bdma_chan *bdma_chan = to_tsi721_chan(dchan); -#ifdef CONFIG_PCI_MSI struct tsi721_device *priv = to_tsi721(dchan->device); -#endif LIST_HEAD(list); dev_dbg(dchan->device->dev, "%s: Entry\n", __func__); @@ -589,14 +587,25 @@ static void tsi721_free_chan_resources(s BUG_ON(!list_empty(&bdma_chan->active_list)); BUG_ON(!list_empty(&bdma_chan->queue)); - tasklet_disable(&bdma_chan->tasklet); + tsi721_bdma_interrupt_enable(bdma_chan, 0); + bdma_chan->active = false; + +#ifdef CONFIG_PCI_MSI + if (priv->flags & TSI721_USING_MSIX) { + synchronize_irq(priv->msix[TSI721_VECT_DMA0_DONE + + bdma_chan->id].vector); + synchronize_irq(priv->msix[TSI721_VECT_DMA0_INT + + bdma_chan->id].vector); + } else +#endif + synchronize_irq(priv->pdev->irq); + + tasklet_kill(&bdma_chan->tasklet); spin_lock_bh(&bdma_chan->lock); list_splice_init(&bdma_chan->free_list, &list); spin_unlock_bh(&bdma_chan->lock); - tsi721_bdma_interrupt_enable(bdma_chan, 0); - #ifdef CONFIG_PCI_MSI if (priv->flags & TSI721_USING_MSIX) { free_irq(priv->msix[TSI721_VECT_DMA0_DONE + @@ -790,6 +799,7 @@ int tsi721_register_dma(struct tsi721_de bdma_chan->dchan.cookie = 1; bdma_chan->dchan.chan_id = i; bdma_chan->id = i; + bdma_chan->active = false; spin_lock_init(&bdma_chan->lock); @@ -799,7 +809,6 @@ int tsi721_register_dma(struct tsi721_de tasklet_init(&bdma_chan->tasklet, tsi721_dma_tasklet, (unsigned long)bdma_chan); - tasklet_disable(&bdma_chan->tasklet); list_add_tail(&bdma_chan->dchan.device_node, &mport->dma.channels); } _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html