Hirak Biswas
aa5d160643
BugLink: https://bugs.launchpad.net/bugs/2080908 On RT kernel spin_lock() behavior changes. It becomes a sleeping lock and spin_lock_irqsave() does not disable IRQs. Due to this, sometimes the DMA IRQ comes while executing a section protected by spin_lock_irqsave(). Since the ISR tries to lock the same spinlock (which is now a sleeping lock) the kernel crashes (BUG: scheduling while atomic: ksoftirqd/0/12/0x00010001). Adding flag to use raw_spin_lock() in case of virtualized DMA drivers so that it behaves like true spinlock even on RT kernel. http://nvbugs/4610804 http://nvbugs/4326086 Signed-off-by: Hirak Biswas <hbiswas@nvidia.com> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Acked-by: Noah Wager <noah.wager@canonical.com> Acked-by: Jacob Martin <jacob.martin@canonical.com> Signed-off-by: Noah Wager <noah.wager@canonical.com>
143 lines
3.4 KiB
C
143 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Virtual DMA channel support for DMAengine
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*
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* Copyright (C) 2012 Russell King
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*/
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#include <linux/device.h>
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#include <linux/dmaengine.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include "virt-dma.h"
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static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
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{
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return container_of(tx, struct virt_dma_desc, tx);
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}
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dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
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{
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struct virt_dma_chan *vc = to_virt_chan(tx->chan);
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struct virt_dma_desc *vd = to_virt_desc(tx);
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unsigned long flags;
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dma_cookie_t cookie;
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dma_vchan_lock_irqsave(vc, flags);
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cookie = dma_cookie_assign(tx);
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list_move_tail(&vd->node, &vc->desc_submitted);
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dma_vchan_unlock_irqrestore(vc, flags);
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dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
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vc, vd, cookie);
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return cookie;
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}
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EXPORT_SYMBOL_GPL(vchan_tx_submit);
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/**
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* vchan_tx_desc_free - free a reusable descriptor
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* @tx: the transfer
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*
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* This function frees a previously allocated reusable descriptor. The only
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* other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
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* transfer.
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*
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* Returns 0 upon success
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*/
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int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
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{
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struct virt_dma_chan *vc = to_virt_chan(tx->chan);
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struct virt_dma_desc *vd = to_virt_desc(tx);
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unsigned long flags;
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dma_vchan_lock_irqsave(vc, flags);
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list_del(&vd->node);
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dma_vchan_unlock_irqrestore(vc, flags);
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dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
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vc, vd, vd->tx.cookie);
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vc->desc_free(vd);
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return 0;
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}
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EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
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struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
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dma_cookie_t cookie)
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{
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struct virt_dma_desc *vd;
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list_for_each_entry(vd, &vc->desc_issued, node)
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if (vd->tx.cookie == cookie)
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return vd;
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return NULL;
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}
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EXPORT_SYMBOL_GPL(vchan_find_desc);
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/*
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* This tasklet handles the completion of a DMA descriptor by
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* calling its callback and freeing it.
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*/
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static void vchan_complete(struct tasklet_struct *t)
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{
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struct virt_dma_chan *vc = from_tasklet(vc, t, task);
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struct virt_dma_desc *vd, *_vd;
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struct dmaengine_desc_callback cb;
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LIST_HEAD(head);
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dma_vchan_lock_irq(vc);
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list_splice_tail_init(&vc->desc_completed, &head);
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vd = vc->cyclic;
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if (vd) {
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vc->cyclic = NULL;
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dmaengine_desc_get_callback(&vd->tx, &cb);
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} else {
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memset(&cb, 0, sizeof(cb));
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}
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dma_vchan_unlock_irq(vc);
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dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
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list_for_each_entry_safe(vd, _vd, &head, node) {
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dmaengine_desc_get_callback(&vd->tx, &cb);
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list_del(&vd->node);
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dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
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vchan_vdesc_fini(vd);
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}
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}
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void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
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{
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struct virt_dma_desc *vd, *_vd;
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list_for_each_entry_safe(vd, _vd, head, node) {
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list_del(&vd->node);
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vchan_vdesc_fini(vd);
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}
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}
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EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
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void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
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{
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dma_cookie_init(&vc->chan);
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dma_vchan_lock_init(vc);
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INIT_LIST_HEAD(&vc->desc_allocated);
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INIT_LIST_HEAD(&vc->desc_submitted);
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INIT_LIST_HEAD(&vc->desc_issued);
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INIT_LIST_HEAD(&vc->desc_completed);
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INIT_LIST_HEAD(&vc->desc_terminated);
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tasklet_setup(&vc->task, vchan_complete);
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vc->chan.device = dmadev;
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list_add_tail(&vc->chan.device_node, &dmadev->channels);
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}
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EXPORT_SYMBOL_GPL(vchan_init);
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MODULE_AUTHOR("Russell King");
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MODULE_LICENSE("GPL");
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