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Date: Thu, 4 Feb 2016 16:13:43 +0300
From: Andrey Ryabinin <aryabinin@...tuozzo.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...nel.org>, <krinkin.m.u@...il.com>,
<mingo@...e.hu>, <peterz@...radead.org>,
<linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: +
kernel-locking-lockdepc-make-lockdep-initialize-itself-on-demand.patch added
to -mm tree
On 02/04/2016 12:44 AM, Andrew Morton wrote:
>
> Probably lockdep_init() and lockdep_initialized can be done away with now.
>
Yup, it probably should be folded into your patch, or we could hold this off for 4.6.
From: Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: kernel/lockdep: eliminate lockdep_init()
Lockdep is initialized at compile time now. Get rid of lockdep_init().
Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
---
arch/c6x/kernel/setup.c | 2 -
arch/microblaze/kernel/setup.c | 2 -
arch/powerpc/kernel/setup_32.c | 2 -
arch/powerpc/kernel/setup_64.c | 3 --
arch/s390/kernel/early.c | 1 -
arch/sparc/kernel/head_64.S | 8 ----
arch/x86/lguest/boot.c | 6 ---
include/linux/lockdep.h | 2 -
init/main.c | 5 ---
kernel/locking/lockdep.c | 59 ---------------------------
tools/lib/lockdep/common.c | 5 ---
tools/lib/lockdep/include/liblockdep/common.h | 1 -
tools/lib/lockdep/preload.c | 2 -
13 files changed, 98 deletions(-)
diff --git a/arch/c6x/kernel/setup.c b/arch/c6x/kernel/setup.c
index 72e17f7..786e36e 100644
--- a/arch/c6x/kernel/setup.c
+++ b/arch/c6x/kernel/setup.c
@@ -281,8 +281,6 @@ notrace void __init machine_init(unsigned long dt_ptr)
*/
set_ist(_vectors_start);
- lockdep_init();
-
/*
* dtb is passed in from bootloader.
* fdt is linked in blob.
diff --git a/arch/microblaze/kernel/setup.c b/arch/microblaze/kernel/setup.c
index 89a2a93..f31ebb5 100644
--- a/arch/microblaze/kernel/setup.c
+++ b/arch/microblaze/kernel/setup.c
@@ -130,8 +130,6 @@ void __init machine_early_init(const char *cmdline, unsigned int ram,
memset(__bss_start, 0, __bss_stop-__bss_start);
memset(_ssbss, 0, _esbss-_ssbss);
- lockdep_init();
-
/* initialize device tree for usage in early_printk */
early_init_devtree(_fdt_start);
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index ad8c9db..d544fa3 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -114,8 +114,6 @@ extern unsigned int memset_nocache_branch; /* Insn to be replaced by NOP */
notrace void __init machine_init(u64 dt_ptr)
{
- lockdep_init();
-
/* Enable early debugging if any specified (see udbg.h) */
udbg_early_init();
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5c03a6a..f98be83 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -255,9 +255,6 @@ void __init early_setup(unsigned long dt_ptr)
setup_paca(&boot_paca);
fixup_boot_paca();
- /* Initialize lockdep early or else spinlocks will blow */
- lockdep_init();
-
/* -------- printk is now safe to use ------- */
/* Enable early debugging if any specified (see udbg.h) */
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index c55576b..a0684de 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -448,7 +448,6 @@ void __init startup_init(void)
rescue_initrd();
clear_bss_section();
init_kernel_storage_key();
- lockdep_init();
lockdep_off();
setup_lowcore_early();
setup_facility_list();
diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index f2d30ca..cd1f592 100644
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -696,14 +696,6 @@ tlb_fixup_done:
call __bzero
sub %o1, %o0, %o1
-#ifdef CONFIG_LOCKDEP
- /* We have this call this super early, as even prom_init can grab
- * spinlocks and thus call into the lockdep code.
- */
- call lockdep_init
- nop
-#endif
-
call prom_init
mov %l7, %o0 ! OpenPROM cif handler
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 4ba229a..f56cc41 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1520,12 +1520,6 @@ __init void lguest_init(void)
*/
reserve_top_address(lguest_data.reserve_mem);
- /*
- * If we don't initialize the lock dependency checker now, it crashes
- * atomic_notifier_chain_register, then paravirt_disable_iospace.
- */
- lockdep_init();
-
/* Hook in our special panic hypercall code. */
atomic_notifier_chain_register(&panic_notifier_list, &paniced);
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 4dca42f..d026b19 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -261,7 +261,6 @@ struct held_lock {
/*
* Initialization, self-test and debugging-output methods:
*/
-extern void lockdep_init(void);
extern void lockdep_info(void);
extern void lockdep_reset(void);
extern void lockdep_reset_lock(struct lockdep_map *lock);
@@ -392,7 +391,6 @@ static inline void lockdep_on(void)
# define lockdep_set_current_reclaim_state(g) do { } while (0)
# define lockdep_clear_current_reclaim_state() do { } while (0)
# define lockdep_trace_alloc(g) do { } while (0)
-# define lockdep_init() do { } while (0)
# define lockdep_info() do { } while (0)
# define lockdep_init_map(lock, name, key, sub) \
do { (void)(name); (void)(key); } while (0)
diff --git a/init/main.c b/init/main.c
index 58c9e37..b3008bc 100644
--- a/init/main.c
+++ b/init/main.c
@@ -499,11 +499,6 @@ asmlinkage __visible void __init start_kernel(void)
char *command_line;
char *after_dashes;
- /*
- * Need to run as early as possible, to initialize the
- * lockdep hash:
- */
- lockdep_init();
set_task_stack_end_magic(&init_task);
smp_setup_processor_id();
debug_objects_early_init();
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 92e4dc6..c873a51 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -123,8 +123,6 @@ static inline int debug_locks_off_graph_unlock(void)
return ret;
}
-static int lockdep_initialized;
-
unsigned long nr_list_entries;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
@@ -434,19 +432,6 @@ unsigned int max_lockdep_depth;
#ifdef CONFIG_DEBUG_LOCKDEP
/*
- * We cannot printk in early bootup code. Not even early_printk()
- * might work. So we mark any initialization errors and printk
- * about it later on, in lockdep_info().
- */
-static int lockdep_init_error;
-static const char *lock_init_error;
-static unsigned long lockdep_init_trace_data[20];
-static struct stack_trace lockdep_init_trace = {
- .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
- .entries = lockdep_init_trace_data,
-};
-
-/*
* Various lockdep statistics:
*/
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
@@ -669,20 +654,6 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
struct hlist_head *hash_head;
struct lock_class *class;
-#ifdef CONFIG_DEBUG_LOCKDEP
- /*
- * If the architecture calls into lockdep before initializing
- * the hashes then we'll warn about it later. (we cannot printk
- * right now)
- */
- if (unlikely(!lockdep_initialized)) {
- lockdep_init();
- lockdep_init_error = 1;
- lock_init_error = lock->name;
- save_stack_trace(&lockdep_init_trace);
- }
-#endif
-
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
debug_locks_off();
printk(KERN_ERR
@@ -4013,28 +3984,6 @@ out_restore:
raw_local_irq_restore(flags);
}
-void lockdep_init(void)
-{
- int i;
-
- /*
- * Some architectures have their own start_kernel()
- * code which calls lockdep_init(), while we also
- * call lockdep_init() from the start_kernel() itself,
- * and we want to initialize the hashes only once:
- */
- if (lockdep_initialized)
- return;
-
- for (i = 0; i < CLASSHASH_SIZE; i++)
- INIT_HLIST_HEAD(classhash_table + i);
-
- for (i = 0; i < CHAINHASH_SIZE; i++)
- INIT_HLIST_HEAD(chainhash_table + i);
-
- lockdep_initialized = 1;
-}
-
void __init lockdep_info(void)
{
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
@@ -4061,14 +4010,6 @@ void __init lockdep_info(void)
printk(" per task-struct memory footprint: %lu bytes\n",
sizeof(struct held_lock) * MAX_LOCK_DEPTH);
-
-#ifdef CONFIG_DEBUG_LOCKDEP
- if (lockdep_init_error) {
- printk("WARNING: lockdep init error: lock '%s' was acquired before lockdep_init().\n", lock_init_error);
- printk("Call stack leading to lockdep invocation was:\n");
- print_stack_trace(&lockdep_init_trace, 0);
- }
-#endif
}
static void
diff --git a/tools/lib/lockdep/common.c b/tools/lib/lockdep/common.c
index 9be6633..d1c89cc 100644
--- a/tools/lib/lockdep/common.c
+++ b/tools/lib/lockdep/common.c
@@ -11,11 +11,6 @@ static __thread struct task_struct current_obj;
bool debug_locks = true;
bool debug_locks_silent;
-__attribute__((constructor)) static void liblockdep_init(void)
-{
- lockdep_init();
-}
-
__attribute__((destructor)) static void liblockdep_exit(void)
{
debug_check_no_locks_held();
diff --git a/tools/lib/lockdep/include/liblockdep/common.h b/tools/lib/lockdep/include/liblockdep/common.h
index a60c14b..6e66277 100644
--- a/tools/lib/lockdep/include/liblockdep/common.h
+++ b/tools/lib/lockdep/include/liblockdep/common.h
@@ -44,7 +44,6 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
void lock_release(struct lockdep_map *lock, int nested,
unsigned long ip);
extern void debug_check_no_locks_freed(const void *from, unsigned long len);
-extern void lockdep_init(void);
#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
{ .name = (_name), .key = (void *)(_key), }
diff --git a/tools/lib/lockdep/preload.c b/tools/lib/lockdep/preload.c
index 21cdf86..5284484 100644
--- a/tools/lib/lockdep/preload.c
+++ b/tools/lib/lockdep/preload.c
@@ -439,7 +439,5 @@ __attribute__((constructor)) static void init_preload(void)
ll_pthread_rwlock_unlock = dlsym(RTLD_NEXT, "pthread_rwlock_unlock");
#endif
- lockdep_init();
-
__init_state = done;
}
--
2.4.10
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