As a bit spinlock, we had no lockdep visibility into the usage
of the list head locking. Now, as a separate lock, we see:
[ 3.613354] BUG: sleeping function called from invalid context at kernel/rtmutex.c:658
[ 3.613356] in_atomic(): 1, irqs_disabled(): 0, pid: 122, name: udevd
[ 3.613357] 5 locks held by udevd/122:
[ 3.613358] #0: (&sb->s_type->i_mutex_key#7/1){+.+.+.}, at: [<ffffffff811967e8>] lock_rename+0xe8/0xf0
[ 3.613363] #1: (rename_lock){+.+...}, at: [<ffffffff811a277c>] d_move+0x2c/0x60
[ 3.613367] #2: (&dentry->d_lock){+.+...}, at: [<ffffffff811a0763>] dentry_lock_for_move+0xf3/0x130
[ 3.613370] #3: (&dentry->d_lock/2){+.+...}, at: [<ffffffff811a0734>] dentry_lock_for_move+0xc4/0x130
[ 3.613373] #4: (&dentry->d_lock/3){+.+...}, at: [<ffffffff811a0747>] dentry_lock_for_move+0xd7/0x130
[ 3.613377] Pid: 122, comm: udevd Not tainted 3.4.47-rt62-00002-gfedcea8 #7
[ 3.613378] Call Trace:
[ 3.613382] [<ffffffff810b9624>] __might_sleep+0x134/0x1f0
[ 3.613385] [<ffffffff817a24d4>] rt_spin_lock+0x24/0x60
[ 3.613387] [<ffffffff811a0c4c>] __d_shrink+0x5c/0xa0
[ 3.613389] [<ffffffff811a1b2d>] __d_drop+0x1d/0x40
[ 3.613391] [<ffffffff811a24be>] __d_move+0x8e/0x320
[ 3.613393] [<ffffffff811a278e>] d_move+0x3e/0x60
[ 3.613394] [<ffffffff81199598>] vfs_rename+0x198/0x4c0
[ 3.613396] [<ffffffff8119b093>] sys_renameat+0x213/0x240
[ 3.613398] [<ffffffff817a2de5>] ? _raw_spin_unlock+0x35/0x60
[ 3.613401] [<ffffffff8107781c>] ? do_page_fault+0x1ec/0x4b0
[ 3.613403] [<ffffffff817a32ca>] ? retint_swapgs+0xe/0x13
[ 3.613406] [<ffffffff813eb0e6>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 3.613408] [<ffffffff8119b0db>] sys_rename+0x1b/0x20
[ 3.613410] [<ffffffff817a3b96>] system_call_fastpath+0x1a/0x1f
For now, lets assume that the list head lock isn't held for big
stretches, and hence it being raw won't be a significant latency
concern.
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
include/linux/list_bl.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
index 9c46fea..64ba33b 100644
--- a/include/linux/list_bl.h
+++ b/include/linux/list_bl.h
@@ -34,7 +34,7 @@
struct hlist_bl_head {
struct hlist_bl_node *first;
#ifdef CONFIG_PREEMPT_RT_BASE
- spinlock_t lock;
+ raw_spinlock_t lock;
#endif
};
@@ -46,7 +46,7 @@ static inline void INIT_HLIST_BL_HEAD(struct hlist_bl_head *h)
{
h->first = NULL;
#ifdef CONFIG_PREEMPT_RT_BASE
- spin_lock_init(&h->lock);
+ raw_spin_lock_init(&h->lock);
#endif
}
@@ -130,7 +130,7 @@ static inline void hlist_bl_lock(struct hlist_bl_head *b)
#ifndef CONFIG_PREEMPT_RT_BASE
bit_spin_lock(0, (unsigned long *)b);
#else
- spin_lock(&b->lock);
+ raw_spin_lock(&b->lock);
#endif
}
@@ -139,7 +139,7 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b)
#ifndef CONFIG_PREEMPT_RT_BASE
__bit_spin_unlock(0, (unsigned long *)b);
#else
- spin_unlock(&b->lock);
+ raw_spin_unlock(&b->lock);
#endif
}
--
1.8.1.2
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