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 <[email protected]>                                 
                                                                                
                                                    
Subject: kernel/lockdep: eliminate lockdep_init()

Lockdep is initialized at compile time now. Get rid of lockdep_init().

Signed-off-by: Andrey Ryabinin <[email protected]>
---
 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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