diff options
Diffstat (limited to 'debian/patches-rt/0068-list_bl-Make-list-head-locking-RT-safe.patch')
| -rw-r--r-- | debian/patches-rt/0068-list_bl-Make-list-head-locking-RT-safe.patch | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/debian/patches-rt/0068-list_bl-Make-list-head-locking-RT-safe.patch b/debian/patches-rt/0068-list_bl-Make-list-head-locking-RT-safe.patch new file mode 100644 index 000000000..940959051 --- /dev/null +++ b/debian/patches-rt/0068-list_bl-Make-list-head-locking-RT-safe.patch @@ -0,0 +1,121 @@ +From c1eeae383297bbad06f5e7b6d1dafa5ff5fb286e 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 068/347] list_bl: Make list head locking RT safe +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +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 3fc2cc57ba1b..69b659259bac 100644 +--- a/include/linux/list_bl.h ++++ b/include/linux/list_bl.h +@@ -3,6 +3,7 @@ + #define _LINUX_LIST_BL_H + + #include <linux/list.h> ++#include <linux/spinlock.h> + #include <linux/bit_spinlock.h> + + /* +@@ -33,13 +34,22 @@ + + 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) + { +@@ -119,12 +129,26 @@ 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) +-- +2.36.1 + |