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.h | 237 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 237 insertions(+) create mode 100644 drivers/dma/virt-dma.h (limited to 'drivers/dma/virt-dma.h') diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h new file mode 100644 index 000000000..59d9eabc8 --- /dev/null +++ b/drivers/dma/virt-dma.h @@ -0,0 +1,237 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Virtual DMA channel support for DMAengine + * + * Copyright (C) 2012 Russell King + */ +#ifndef VIRT_DMA_H +#define VIRT_DMA_H + +#include +#include + +#include "dmaengine.h" + +struct virt_dma_desc { + struct dma_async_tx_descriptor tx; + struct dmaengine_result tx_result; + /* protected by vc.lock */ + struct list_head node; +}; + +struct virt_dma_chan { + struct dma_chan chan; + struct tasklet_struct task; + void (*desc_free)(struct virt_dma_desc *); + + spinlock_t lock; + + /* protected by vc.lock */ + struct list_head desc_allocated; + struct list_head desc_submitted; + struct list_head desc_issued; + struct list_head desc_completed; + struct list_head desc_terminated; + + struct virt_dma_desc *cyclic; +}; + +static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan) +{ + return container_of(chan, struct virt_dma_chan, chan); +} + +void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head); +void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev); +struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t); +extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *); +extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *); + +/** + * vchan_tx_prep - prepare a descriptor + * @vc: virtual channel allocating this descriptor + * @vd: virtual descriptor to prepare + * @tx_flags: flags argument passed in to prepare function + */ +static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc, + struct virt_dma_desc *vd, unsigned long tx_flags) +{ + unsigned long flags; + + dma_async_tx_descriptor_init(&vd->tx, &vc->chan); + vd->tx.flags = tx_flags; + vd->tx.tx_submit = vchan_tx_submit; + vd->tx.desc_free = vchan_tx_desc_free; + + vd->tx_result.result = DMA_TRANS_NOERROR; + vd->tx_result.residue = 0; + + spin_lock_irqsave(&vc->lock, flags); + list_add_tail(&vd->node, &vc->desc_allocated); + spin_unlock_irqrestore(&vc->lock, flags); + + return &vd->tx; +} + +/** + * vchan_issue_pending - move submitted descriptors to issued list + * @vc: virtual channel to update + * + * vc.lock must be held by caller + */ +static inline bool vchan_issue_pending(struct virt_dma_chan *vc) +{ + lockdep_assert_held(&vc->lock); + + list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued); + return !list_empty(&vc->desc_issued); +} + +/** + * vchan_cookie_complete - report completion of a descriptor + * @vd: virtual descriptor to update + * + * vc.lock must be held by caller + */ +static inline void vchan_cookie_complete(struct virt_dma_desc *vd) +{ + struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); + dma_cookie_t cookie; + + lockdep_assert_held(&vc->lock); + + cookie = vd->tx.cookie; + dma_cookie_complete(&vd->tx); + dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n", + vd, cookie); + list_add_tail(&vd->node, &vc->desc_completed); + + tasklet_schedule(&vc->task); +} + +/** + * vchan_vdesc_fini - Free or reuse a descriptor + * @vd: virtual descriptor to free/reuse + */ +static inline void vchan_vdesc_fini(struct virt_dma_desc *vd) +{ + struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); + + if (dmaengine_desc_test_reuse(&vd->tx)) { + unsigned long flags; + + spin_lock_irqsave(&vc->lock, flags); + list_add(&vd->node, &vc->desc_allocated); + spin_unlock_irqrestore(&vc->lock, flags); + } else { + vc->desc_free(vd); + } +} + +/** + * vchan_cyclic_callback - report the completion of a period + * @vd: virtual descriptor + */ +static inline void vchan_cyclic_callback(struct virt_dma_desc *vd) +{ + struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); + + vc->cyclic = vd; + tasklet_schedule(&vc->task); +} + +/** + * vchan_terminate_vdesc - Disable pending cyclic callback + * @vd: virtual descriptor to be terminated + * + * vc.lock must be held by caller + */ +static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd) +{ + struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); + + lockdep_assert_held(&vc->lock); + + list_add_tail(&vd->node, &vc->desc_terminated); + + if (vc->cyclic == vd) + vc->cyclic = NULL; +} + +/** + * vchan_next_desc - peek at the next descriptor to be processed + * @vc: virtual channel to obtain descriptor from + * + * vc.lock must be held by caller + */ +static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc) +{ + lockdep_assert_held(&vc->lock); + + return list_first_entry_or_null(&vc->desc_issued, + struct virt_dma_desc, node); +} + +/** + * vchan_get_all_descriptors - obtain all submitted and issued descriptors + * @vc: virtual channel to get descriptors from + * @head: list of descriptors found + * + * vc.lock must be held by caller + * + * Removes all submitted and issued descriptors from internal lists, and + * provides a list of all descriptors found + */ +static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc, + struct list_head *head) +{ + lockdep_assert_held(&vc->lock); + + list_splice_tail_init(&vc->desc_allocated, head); + list_splice_tail_init(&vc->desc_submitted, head); + list_splice_tail_init(&vc->desc_issued, head); + list_splice_tail_init(&vc->desc_completed, head); + list_splice_tail_init(&vc->desc_terminated, head); +} + +static inline void vchan_free_chan_resources(struct virt_dma_chan *vc) +{ + struct virt_dma_desc *vd; + unsigned long flags; + LIST_HEAD(head); + + spin_lock_irqsave(&vc->lock, flags); + vchan_get_all_descriptors(vc, &head); + list_for_each_entry(vd, &head, node) + dmaengine_desc_clear_reuse(&vd->tx); + spin_unlock_irqrestore(&vc->lock, flags); + + vchan_dma_desc_free_list(vc, &head); +} + +/** + * vchan_synchronize() - synchronize callback execution to the current context + * @vc: virtual channel to synchronize + * + * Makes sure that all scheduled or active callbacks have finished running. For + * proper operation the caller has to ensure that no new callbacks are scheduled + * after the invocation of this function started. + * Free up the terminated cyclic descriptor to prevent memory leakage. + */ +static inline void vchan_synchronize(struct virt_dma_chan *vc) +{ + LIST_HEAD(head); + unsigned long flags; + + tasklet_kill(&vc->task); + + spin_lock_irqsave(&vc->lock, flags); + + list_splice_tail_init(&vc->desc_terminated, &head); + + spin_unlock_irqrestore(&vc->lock, flags); + + vchan_dma_desc_free_list(vc, &head); +} + +#endif -- cgit v1.3.1