#include #include #include #include "internal.h" #include "mount.h" static DEFINE_SPINLOCK(pin_lock); void pin_remove(struct fs_pin *pin) { spin_lock(&pin_lock); hlist_del_init(&pin->m_list); hlist_del_init(&pin->s_list); spin_unlock(&pin_lock); spin_lock_irq(&pin->wait.lock); pin->done = 1; wake_up_locked(&pin->wait); spin_unlock_irq(&pin->wait.lock); } void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p) { spin_lock(&pin_lock); if (p) hlist_add_head(&pin->s_list, p); hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins); spin_unlock(&pin_lock); } void pin_insert(struct fs_pin *pin, struct vfsmount *m) { pin_insert_group(pin, m, &m->mnt_sb->s_pins); } void pin_kill(struct fs_pin *p) { wait_queue_t wait; if (!p) { rcu_read_unlock(); return; } init_wait(&wait); spin_lock_irq(&p->wait.lock); if (likely(!p->done)) { p->done = -1; spin_unlock_irq(&p->wait.lock); rcu_read_unlock(); p->kill(p); return; } if (p->done > 0) { spin_unlock_irq(&p->wait.lock); rcu_read_unlock(); return; } __add_wait_queue(&p->wait, &wait); while (1) { set_current_state(TASK_UNINTERRUPTIBLE); spin_unlock_irq(&p->wait.lock); rcu_read_unlock(); schedule(); rcu_read_lock(); if (likely(list_empty(&wait.task_list))) break; /* OK, we know p couldn't have been freed yet */ spin_lock_irq(&p->wait.lock); if (p->done > 0) { spin_unlock_irq(&p->wait.lock); break; } } rcu_read_unlock(); } void mnt_pin_kill(struct mount *m) { while (1) { struct hlist_node *p; rcu_read_lock(); p = ACCESS_ONCE(m->mnt_pins.first); if (!p) { rcu_read_unlock(); break; } pin_kill(hlist_entry(p, struct fs_pin, m_list)); } } void group_pin_kill(struct hlist_head *p) { while (1) { struct hlist_node *q; rcu_read_lock(); q = ACCESS_ONCE(p->first); if (!q) { rcu_read_unlock(); break; } pin_kill(hlist_entry(q, struct fs_pin, s_list)); } } eef542c5414e54bf1a'>commitdiff
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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 /tools/perf/util/config.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 'tools/perf/util/config.h')