From 5a26db5bd25cf4bf32ae9fa9f6136b6b6d5b45c5 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 16 Jan 2008 09:51:58 +0100 Subject: [PATCH 1/3] lockdep: fix internal double unlock during self-test Lockdep, during self-test (when it was simulating double unlocks) was sometimes unconditionally unlocking a spinlock when it had not been locked. This won't work for ticket locks. Signed-off-by: Nick Piggin Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- kernel/lockdep.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 723bd9f92556..4335f12a27c6 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -2943,9 +2943,10 @@ void lockdep_free_key_range(void *start, unsigned long size) struct list_head *head; unsigned long flags; int i; + int locked; raw_local_irq_save(flags); - graph_lock(); + locked = graph_lock(); /* * Unhash all classes that were created by this module: @@ -2959,7 +2960,8 @@ void lockdep_free_key_range(void *start, unsigned long size) zap_class(class); } - graph_unlock(); + if (locked) + graph_unlock(); raw_local_irq_restore(flags); } @@ -2969,6 +2971,7 @@ void lockdep_reset_lock(struct lockdep_map *lock) struct list_head *head; unsigned long flags; int i, j; + int locked; raw_local_irq_save(flags); @@ -2987,7 +2990,7 @@ void lockdep_reset_lock(struct lockdep_map *lock) * Debug check: in the end all mapped classes should * be gone. */ - graph_lock(); + locked = graph_lock(); for (i = 0; i < CLASSHASH_SIZE; i++) { head = classhash_table + i; if (list_empty(head)) @@ -3000,7 +3003,8 @@ void lockdep_reset_lock(struct lockdep_map *lock) } } } - graph_unlock(); + if (locked) + graph_unlock(); out_restore: raw_local_irq_restore(flags); From eb13ba873881abd5e15af784756a61af635e665e Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 16 Jan 2008 09:51:58 +0100 Subject: [PATCH 2/3] lockdep: fix workqueue creation API lockdep interaction Dave Young reported warnings from lockdep that the workqueue API can sometimes try to register lockdep classes with the same key but different names. This is not permitted in lockdep. Unfortunately, I was unaware of that restriction when I wrote the code to debug workqueue problems with lockdep and used the workqueue name as the lockdep class name. This can obviously lead to the problem if the workqueue name is dynamic. This patch solves the problem by always using a constant name for the workqueue's lockdep class, namely either the constant name that was passed in or a string consisting of the variable name. Signed-off-by: Johannes Berg Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- include/linux/workqueue.h | 14 +++++++++++--- kernel/workqueue.c | 5 +++-- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 7daafdc2514b..7f28c32d9aca 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -149,19 +149,27 @@ struct execute_work { extern struct workqueue_struct * __create_workqueue_key(const char *name, int singlethread, - int freezeable, struct lock_class_key *key); + int freezeable, struct lock_class_key *key, + const char *lock_name); #ifdef CONFIG_LOCKDEP #define __create_workqueue(name, singlethread, freezeable) \ ({ \ static struct lock_class_key __key; \ + const char *__lock_name; \ + \ + if (__builtin_constant_p(name)) \ + __lock_name = (name); \ + else \ + __lock_name = #name; \ \ __create_workqueue_key((name), (singlethread), \ - (freezeable), &__key); \ + (freezeable), &__key, \ + __lock_name); \ }) #else #define __create_workqueue(name, singlethread, freezeable) \ - __create_workqueue_key((name), (singlethread), (freezeable), NULL) + __create_workqueue_key((name), (singlethread), (freezeable), NULL, NULL) #endif #define create_workqueue(name) __create_workqueue((name), 0, 0) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 52d5e7c9a8e6..8db0b597509e 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -722,7 +722,8 @@ static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) struct workqueue_struct *__create_workqueue_key(const char *name, int singlethread, int freezeable, - struct lock_class_key *key) + struct lock_class_key *key, + const char *lock_name) { struct workqueue_struct *wq; struct cpu_workqueue_struct *cwq; @@ -739,7 +740,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name, } wq->name = name; - lockdep_init_map(&wq->lockdep_map, name, key, 0); + lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); wq->singlethread = singlethread; wq->freezeable = freezeable; INIT_LIST_HEAD(&wq->list); From fb1dac909d94ff807cd833d340c6827c3a957159 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 16 Jan 2008 09:51:59 +0100 Subject: [PATCH 3/3] lockdep: more hardirq annotations for notify_die() On Sat, 2007-12-29 at 18:06 +0100, Marcin Slusarz wrote: > Hi > Today I've got this (while i was upgrading my gentoo box): > > WARNING: at kernel/lockdep.c:2658 check_flags() > Pid: 21680, comm: conftest Not tainted 2.6.24-rc6 #63 > > Call Trace: > [] check_flags+0x1c7/0x1d0 > [] lock_acquire+0x57/0xc0 > [] __atomic_notifier_call_chain+0x60/0xd0 > [] atomic_notifier_call_chain+0x11/0x20 > [] notify_die+0x2e/0x30 > [] do_divide_error+0x5a/0xa0 > [] trace_hardirqs_on_thunk+0x35/0x3a > [] trace_hardirqs_on+0xd9/0x180 > [] trace_hardirqs_on_thunk+0x35/0x3a > [] error_exit+0x0/0xa9 > > possible reason: unannotated irqs-off. > irq event stamp: 4693 > hardirqs last enabled at (4693): [] trace_hardirqs_on_thunk+0x35/0x3a > hardirqs last disabled at (4692): [] trace_hardirqs_off_thunk+0x35/0x37 > softirqs last enabled at (3546): [] __do_softirq+0xb3/0xd0 > softirqs last disabled at (3521): [] call_softirq+0x1c/0x30 more early fixups for notify_die().. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps_32.c | 1 + arch/x86/kernel/traps_64.c | 1 + 2 files changed, 2 insertions(+) diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c index c88bbffcaa03..02d1e1e58e81 100644 --- a/arch/x86/kernel/traps_32.c +++ b/arch/x86/kernel/traps_32.c @@ -541,6 +541,7 @@ fastcall void do_##name(struct pt_regs * regs, long error_code) \ info.si_errno = 0; \ info.si_code = sicode; \ info.si_addr = (void __user *)siaddr; \ + trace_hardirqs_fixup(); \ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \ == NOTIFY_STOP) \ return; \ diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index d11525ad81b4..cc68b92316cd 100644 --- a/arch/x86/kernel/traps_64.c +++ b/arch/x86/kernel/traps_64.c @@ -635,6 +635,7 @@ asmlinkage void do_##name(struct pt_regs * regs, long error_code) \ info.si_errno = 0; \ info.si_code = sicode; \ info.si_addr = (void __user *)siaddr; \ + trace_hardirqs_fixup(); \ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \ == NOTIFY_STOP) \ return; \