From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/dma/virt-dma.c | 143 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 drivers/dma/virt-dma.c (limited to 'drivers/dma/virt-dma.c') diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c new file mode 100644 index 000000000..7961172a7 --- /dev/null +++ b/drivers/dma/virt-dma.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Virtual DMA channel support for DMAengine + * + * Copyright (C) 2012 Russell King + */ +#include +#include +#include +#include + +#include "virt-dma.h" + +static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx) +{ + return container_of(tx, struct virt_dma_desc, tx); +} + +dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx) +{ + struct virt_dma_chan *vc = to_virt_chan(tx->chan); + struct virt_dma_desc *vd = to_virt_desc(tx); + unsigned long flags; + dma_cookie_t cookie; + + spin_lock_irqsave(&vc->lock, flags); + cookie = dma_cookie_assign(tx); + + list_move_tail(&vd->node, &vc->desc_submitted); + spin_unlock_irqrestore(&vc->lock, flags); + + dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n", + vc, vd, cookie); + + return cookie; +} +EXPORT_SYMBOL_GPL(vchan_tx_submit); + +/** + * vchan_tx_desc_free - free a reusable descriptor + * @tx: the transfer + * + * This function frees a previously allocated reusable descriptor. The only + * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the + * transfer. + * + * Returns 0 upon success + */ +int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx) +{ + struct virt_dma_chan *vc = to_virt_chan(tx->chan); + struct virt_dma_desc *vd = to_virt_desc(tx); + unsigned long flags; + + spin_lock_irqsave(&vc->lock, flags); + list_del(&vd->node); + spin_unlock_irqrestore(&vc->lock, flags); + + dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n", + vc, vd, vd->tx.cookie); + vc->desc_free(vd); + return 0; +} +EXPORT_SYMBOL_GPL(vchan_tx_desc_free); + +struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc, + dma_cookie_t cookie) +{ + struct virt_dma_desc *vd; + + list_for_each_entry(vd, &vc->desc_issued, node) + if (vd->tx.cookie == cookie) + return vd; + + return NULL; +} +EXPORT_SYMBOL_GPL(vchan_find_desc); + +/* + * This tasklet handles the completion of a DMA descriptor by + * calling its callback and freeing it. + */ +static void vchan_complete(struct tasklet_struct *t) +{ + struct virt_dma_chan *vc = from_tasklet(vc, t, task); + struct virt_dma_desc *vd, *_vd; + struct dmaengine_desc_callback cb; + LIST_HEAD(head); + + spin_lock_irq(&vc->lock); + list_splice_tail_init(&vc->desc_completed, &head); + vd = vc->cyclic; + if (vd) { + vc->cyclic = NULL; + dmaengine_desc_get_callback(&vd->tx, &cb); + } else { + memset(&cb, 0, sizeof(cb)); + } + spin_unlock_irq(&vc->lock); + + dmaengine_desc_callback_invoke(&cb, &vd->tx_result); + + list_for_each_entry_safe(vd, _vd, &head, node) { + dmaengine_desc_get_callback(&vd->tx, &cb); + + list_del(&vd->node); + dmaengine_desc_callback_invoke(&cb, &vd->tx_result); + vchan_vdesc_fini(vd); + } +} + +void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head) +{ + struct virt_dma_desc *vd, *_vd; + + list_for_each_entry_safe(vd, _vd, head, node) { + list_del(&vd->node); + vchan_vdesc_fini(vd); + } +} +EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list); + +void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev) +{ + dma_cookie_init(&vc->chan); + + spin_lock_init(&vc->lock); + INIT_LIST_HEAD(&vc->desc_allocated); + INIT_LIST_HEAD(&vc->desc_submitted); + INIT_LIST_HEAD(&vc->desc_issued); + INIT_LIST_HEAD(&vc->desc_completed); + INIT_LIST_HEAD(&vc->desc_terminated); + + tasklet_setup(&vc->task, vchan_complete); + + vc->chan.device = dmadev; + list_add_tail(&vc->chan.device_node, &dmadev->channels); +} +EXPORT_SYMBOL_GPL(vchan_init); + +MODULE_AUTHOR("Russell King"); +MODULE_DESCRIPTION("Virtual DMA channel support for DMAengine"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1