#include #include void __init_swait_queue_head(struct swait_queue_head *q, const char *name, struct lock_class_key *key) { raw_spin_lock_init(&q->lock); lockdep_set_class_and_name(&q->lock, key, name); INIT_LIST_HEAD(&q->task_list); } EXPORT_SYMBOL(__init_swait_queue_head); /* * The thing about the wake_up_state() return value; I think we can ignore it. * * If for some reason it would return 0, that means the previously waiting * task is already running, so it will observe condition true (or has already). */ void swake_up_locked(struct swait_queue_head *q) { struct swait_queue *curr; if (list_empty(&q->task_list)) return; curr = list_first_entry(&q->task_list, typeof(*curr), task_list); wake_up_process(curr->task); list_del_init(&curr->task_list); } EXPORT_SYMBOL(swake_up_locked); void swake_up(struct swait_queue_head *q) { unsigned long flags; if (!swait_active(q)) return; raw_spin_lock_irqsave(&q->lock, flags); swake_up_locked(q); raw_spin_unlock_irqrestore(&q->lock, flags); } EXPORT_SYMBOL(swake_up); /* * Does not allow usage from IRQ disabled, since we must be able to * release IRQs to guarantee bounded hold time. */ void swake_up_all(struct swait_queue_head *q) { struct swait_queue *curr; LIST_HEAD(tmp); if (!swait_active(q)) return; raw_spin_lock_irq(&q->lock); list_splice_init(&q->task_list, &tmp); while (!list_empty(&tmp)) { curr = list_first_entry(&tmp, typeof(*curr), task_list); wake_up_state(curr->task, TASK_NORMAL); list_del_init(&curr->task_list); if (list_empty(&tmp)) break; raw_spin_unlock_irq(&q->lock); raw_spin_lock_irq(&q->lock); } raw_spin_unlock_irq(&q->lock); } EXPORT_SYMBOL(swake_up_all); void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) { wait->task = current; if (list_empty(&wait->task_list)) list_add(&wait->task_list, &q->task_list); } void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state) { unsigned long flags; raw_spin_lock_irqsave(&q->lock, flags); __prepare_to_swait(q, wait); set_current_state(state); raw_spin_unlock_irqrestore(&q->lock, flags); } EXPORT_SYMBOL(prepare_to_swait); long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) { if (signal_pending_state(state, current)) return -ERESTARTSYS; prepare_to_swait(q, wait, state); return 0; } EXPORT_SYMBOL(prepare_to_swait_event); void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) { __set_current_state(TASK_RUNNING); if (!list_empty(&wait->task_list)) list_del_init(&wait->task_list); } void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) { unsigned long flags; __set_current_state(TASK_RUNNING); if (!list_empty_careful(&wait->task_list)) { raw_spin_lock_irqsave(&q->lock, flags); list_del_init(&wait->task_list); raw_spin_unlock_irqrestore(&q->lock, flags); } } EXPORT_SYMBOL(finish_swait); root/include/dt-bindings/mfd/dbx500-prcmu.h
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authorIago Abal <mail@iagoabal.eu>2017-01-11 14:00:21 +0100
committerVinod Koul <vinod.koul@intel.com>2017-01-25 15:35:11 +0530
commit91539eb1fda2d530d3b268eef542c5414e54bf1a (patch)
tree960f5ca6342ad20837aff18aad6e8ecd7da32fd6 /include/dt-bindings/mfd/dbx500-prcmu.h
parent6610d0edf6dc7ee97e46ab3a538a565c79d26199 (diff)
dmaengine: pl330: fix double lock
The static bug finder EBA (http://www.iagoabal.eu/eba/) reported the following double-lock bug: Double lock: 1. spin_lock_irqsave(pch->lock, flags) at pl330_free_chan_resources:2236; 2. call to function `pl330_release_channel' immediately after; 3. call to function `dma_pl330_rqcb' in line 1753; 4. spin_lock_irqsave(pch->lock, flags) at dma_pl330_rqcb:1505. I have fixed it as suggested by Marek Szyprowski. First, I have replaced `pch->lock' with `pl330->lock' in functions `pl330_alloc_chan_resources' and `pl330_free_chan_resources'. This avoids the double-lock by acquiring a different lock than `dma_pl330_rqcb'. NOTE that, as a result, `pl330_free_chan_resources' executes `list_splice_tail_init' on `pch->work_list' under lock `pl330->lock', whereas in the rest of the code `pch->work_list' is protected by `pch->lock'. I don't know if this may cause race conditions. Similarly `pch->cyclic' is written by `pl330_alloc_chan_resources' under `pl330->lock' but read by `pl330_tx_submit' under `pch->lock'. Second, I have removed locking from `pl330_request_channel' and `pl330_release_channel' functions. Function `pl330_request_channel' is only called from `pl330_alloc_chan_resources', so the lock is already held. Function `pl330_release_channel' is called from `pl330_free_chan_resources', which already holds the lock, and from `pl330_del'. Function `pl330_del' is called in an error path of `pl330_probe' and at the end of `pl330_remove', but I assume that there cannot be concurrent accesses to the protected data at those points. Signed-off-by: Iago Abal <mail@iagoabal.eu> Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'include/dt-bindings/mfd/dbx500-prcmu.h')