forked from rrcarlosr/Jetpack
120 lines
3.9 KiB
Diff
120 lines
3.9 KiB
Diff
From bacc5494ca98e977e5db9920e9650cdf5438bc1a Mon Sep 17 00:00:00 2001
|
|
From: Paul Gortmaker <paul.gortmaker@windriver.com>
|
|
Date: Fri, 21 Jun 2013 15:07:25 -0400
|
|
Subject: [PATCH 095/352] list_bl: Make list head locking RT safe
|
|
|
|
As per changes in include/linux/jbd_common.h for avoiding the
|
|
bit_spin_locks on RT ("fs: jbd/jbd2: Make state lock and journal
|
|
head lock rt safe") we do the same thing here.
|
|
|
|
We use the non atomic __set_bit and __clear_bit inside the scope of
|
|
the lock to preserve the ability of the existing LIST_DEBUG code to
|
|
use the zero'th bit in the sanity checks.
|
|
|
|
As a bit spinlock, we had no lockdep visibility into the usage
|
|
of the list head locking. Now, if we were to implement it as a
|
|
standard non-raw spinlock, we would see:
|
|
|
|
BUG: sleeping function called from invalid context at kernel/rtmutex.c:658
|
|
in_atomic(): 1, irqs_disabled(): 0, pid: 122, name: udevd
|
|
5 locks held by udevd/122:
|
|
#0: (&sb->s_type->i_mutex_key#7/1){+.+.+.}, at: [<ffffffff811967e8>] lock_rename+0xe8/0xf0
|
|
#1: (rename_lock){+.+...}, at: [<ffffffff811a277c>] d_move+0x2c/0x60
|
|
#2: (&dentry->d_lock){+.+...}, at: [<ffffffff811a0763>] dentry_lock_for_move+0xf3/0x130
|
|
#3: (&dentry->d_lock/2){+.+...}, at: [<ffffffff811a0734>] dentry_lock_for_move+0xc4/0x130
|
|
#4: (&dentry->d_lock/3){+.+...}, at: [<ffffffff811a0747>] dentry_lock_for_move+0xd7/0x130
|
|
Pid: 122, comm: udevd Not tainted 3.4.47-rt62 #7
|
|
Call Trace:
|
|
[<ffffffff810b9624>] __might_sleep+0x134/0x1f0
|
|
[<ffffffff817a24d4>] rt_spin_lock+0x24/0x60
|
|
[<ffffffff811a0c4c>] __d_shrink+0x5c/0xa0
|
|
[<ffffffff811a1b2d>] __d_drop+0x1d/0x40
|
|
[<ffffffff811a24be>] __d_move+0x8e/0x320
|
|
[<ffffffff811a278e>] d_move+0x3e/0x60
|
|
[<ffffffff81199598>] vfs_rename+0x198/0x4c0
|
|
[<ffffffff8119b093>] sys_renameat+0x213/0x240
|
|
[<ffffffff817a2de5>] ? _raw_spin_unlock+0x35/0x60
|
|
[<ffffffff8107781c>] ? do_page_fault+0x1ec/0x4b0
|
|
[<ffffffff817a32ca>] ? retint_swapgs+0xe/0x13
|
|
[<ffffffff813eb0e6>] ? trace_hardirqs_on_thunk+0x3a/0x3f
|
|
[<ffffffff8119b0db>] sys_rename+0x1b/0x20
|
|
[<ffffffff817a3b96>] system_call_fastpath+0x1a/0x1f
|
|
|
|
Since we are only taking the lock during short lived list operations,
|
|
lets assume for now that it being raw won't be a significant latency
|
|
concern.
|
|
|
|
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
include/linux/list_bl.h | 28 ++++++++++++++++++++++++++--
|
|
1 file changed, 26 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
|
|
index cb48330..d3af099 100644
|
|
--- a/include/linux/list_bl.h
|
|
+++ b/include/linux/list_bl.h
|
|
@@ -2,6 +2,7 @@
|
|
#define _LINUX_LIST_BL_H
|
|
|
|
#include <linux/list.h>
|
|
+#include <linux/spinlock.h>
|
|
#include <linux/bit_spinlock.h>
|
|
|
|
/*
|
|
@@ -32,13 +33,22 @@
|
|
|
|
struct hlist_bl_head {
|
|
struct hlist_bl_node *first;
|
|
+#ifdef CONFIG_PREEMPT_RT_BASE
|
|
+ raw_spinlock_t lock;
|
|
+#endif
|
|
};
|
|
|
|
struct hlist_bl_node {
|
|
struct hlist_bl_node *next, **pprev;
|
|
};
|
|
-#define INIT_HLIST_BL_HEAD(ptr) \
|
|
- ((ptr)->first = NULL)
|
|
+
|
|
+static inline void INIT_HLIST_BL_HEAD(struct hlist_bl_head *h)
|
|
+{
|
|
+ h->first = NULL;
|
|
+#ifdef CONFIG_PREEMPT_RT_BASE
|
|
+ raw_spin_lock_init(&h->lock);
|
|
+#endif
|
|
+}
|
|
|
|
static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h)
|
|
{
|
|
@@ -118,12 +128,26 @@ static inline void hlist_bl_del_init(struct hlist_bl_node *n)
|
|
|
|
static inline void hlist_bl_lock(struct hlist_bl_head *b)
|
|
{
|
|
+#ifndef CONFIG_PREEMPT_RT_BASE
|
|
bit_spin_lock(0, (unsigned long *)b);
|
|
+#else
|
|
+ raw_spin_lock(&b->lock);
|
|
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
+ __set_bit(0, (unsigned long *)b);
|
|
+#endif
|
|
+#endif
|
|
}
|
|
|
|
static inline void hlist_bl_unlock(struct hlist_bl_head *b)
|
|
{
|
|
+#ifndef CONFIG_PREEMPT_RT_BASE
|
|
__bit_spin_unlock(0, (unsigned long *)b);
|
|
+#else
|
|
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
+ __clear_bit(0, (unsigned long *)b);
|
|
+#endif
|
|
+ raw_spin_unlock(&b->lock);
|
|
+#endif
|
|
}
|
|
|
|
static inline bool hlist_bl_is_locked(struct hlist_bl_head *b)
|
|
--
|
|
2.7.4
|
|
|