The patch titled
lockdep: remove mutex deadlock checking code
has been removed from the -mm tree. Its filename is
lockdep-remove-mutex-deadlock-checking-code.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: lockdep: remove mutex deadlock checking code
From: Ingo Molnar <mingo@xxxxxxx>
With the lock validator we detect mutex deadlocks (and more), the mutex
deadlock checking code is both redundant and slower. So remove it.
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/mutex-debug.c | 316 -----------------------------------------
lib/Kconfig.debug | 8 -
2 files changed, 324 deletions(-)
diff -puN kernel/mutex-debug.c~lockdep-remove-mutex-deadlock-checking-code kernel/mutex-debug.c
--- a/kernel/mutex-debug.c~lockdep-remove-mutex-deadlock-checking-code
+++ a/kernel/mutex-debug.c
@@ -51,321 +51,6 @@ LIST_HEAD(debug_mutex_held_locks);
*/
int debug_mutex_on = 1;
-static void printk_task(struct task_struct *p)
-{
- if (p)
- printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
- else
- printk("<none>");
-}
-
-static void printk_ti(struct thread_info *ti)
-{
- if (ti)
- printk_task(ti->task);
- else
- printk("<none>");
-}
-
-static void printk_task_short(struct task_struct *p)
-{
- if (p)
- printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
- else
- printk("<none>");
-}
-
-static void printk_lock(struct mutex *lock, int print_owner)
-{
- printk(" [%p] {%s}\n", lock, lock->name);
-
- if (print_owner && lock->owner) {
- printk(".. held by: ");
- printk_ti(lock->owner);
- printk("\n");
- }
- if (lock->owner) {
- printk("... acquired at: ");
- print_symbol("%s\n", lock->acquire_ip);
- }
-}
-
-/*
- * printk locks held by a task:
- */
-static void show_task_locks(struct task_struct *p)
-{
- switch (p->state) {
- case TASK_RUNNING: printk("R"); break;
- case TASK_INTERRUPTIBLE: printk("S"); break;
- case TASK_UNINTERRUPTIBLE: printk("D"); break;
- case TASK_STOPPED: printk("T"); break;
- case EXIT_ZOMBIE: printk("Z"); break;
- case EXIT_DEAD: printk("X"); break;
- default: printk("?"); break;
- }
- printk_task(p);
- if (p->blocked_on) {
- struct mutex *lock = p->blocked_on->lock;
-
- printk(" blocked on mutex:");
- printk_lock(lock, 1);
- } else
- printk(" (not blocked on mutex)\n");
-}
-
-/*
- * printk all locks held in the system (if filter == NULL),
- * or all locks belonging to a single task (if filter != NULL):
- */
-void show_held_locks(struct task_struct *filter)
-{
- struct list_head *curr, *cursor = NULL;
- struct mutex *lock;
- struct thread_info *t;
- unsigned long flags;
- int count = 0;
-
- if (filter) {
- printk("------------------------------\n");
- printk("| showing all locks held by: | (");
- printk_task_short(filter);
- printk("):\n");
- printk("------------------------------\n");
- } else {
- printk("---------------------------\n");
- printk("| showing all locks held: |\n");
- printk("---------------------------\n");
- }
-
- /*
- * Play safe and acquire the global trace lock. We
- * cannot printk with that lock held so we iterate
- * very carefully:
- */
-next:
- debug_spin_lock_save(&debug_mutex_lock, flags);
- list_for_each(curr, &debug_mutex_held_locks) {
- if (cursor && curr != cursor)
- continue;
- lock = list_entry(curr, struct mutex, held_list);
- t = lock->owner;
- if (filter && (t != filter->thread_info))
- continue;
- count++;
- cursor = curr->next;
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
- printk("\n#%03d: ", count);
- printk_lock(lock, filter ? 0 : 1);
- goto next;
- }
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
- printk("\n");
-}
-
-void mutex_debug_show_all_locks(void)
-{
- struct task_struct *g, *p;
- int count = 10;
- int unlock = 1;
-
- printk("\nShowing all blocking locks in the system:\n");
-
- /*
- * Here we try to get the tasklist_lock as hard as possible,
- * if not successful after 2 seconds we ignore it (but keep
- * trying). This is to enable a debug printout even if a
- * tasklist_lock-holding task deadlocks or crashes.
- */
-retry:
- if (!read_trylock(&tasklist_lock)) {
- if (count == 10)
- printk("hm, tasklist_lock locked, retrying... ");
- if (count) {
- count--;
- printk(" #%d", 10-count);
- mdelay(200);
- goto retry;
- }
- printk(" ignoring it.\n");
- unlock = 0;
- }
- if (count != 10)
- printk(" locked it.\n");
-
- do_each_thread(g, p) {
- show_task_locks(p);
- if (!unlock)
- if (read_trylock(&tasklist_lock))
- unlock = 1;
- } while_each_thread(g, p);
-
- printk("\n");
- show_held_locks(NULL);
- printk("=============================================\n\n");
-
- if (unlock)
- read_unlock(&tasklist_lock);
-}
-
-static void report_deadlock(struct task_struct *task, struct mutex *lock,
- struct mutex *lockblk, unsigned long ip)
-{
- printk("\n%s/%d is trying to acquire this lock:\n",
- current->comm, current->pid);
- printk_lock(lock, 1);
- printk("... trying at: ");
- print_symbol("%s\n", ip);
- show_held_locks(current);
-
- if (lockblk) {
- printk("but %s/%d is deadlocking current task %s/%d!\n\n",
- task->comm, task->pid, current->comm, current->pid);
- printk("\n%s/%d is blocked on this lock:\n",
- task->comm, task->pid);
- printk_lock(lockblk, 1);
-
- show_held_locks(task);
-
- printk("\n%s/%d's [blocked] stackdump:\n\n",
- task->comm, task->pid);
- show_stack(task, NULL);
- }
-
- printk("\n%s/%d's [current] stackdump:\n\n",
- current->comm, current->pid);
- dump_stack();
- mutex_debug_show_all_locks();
- printk("[ turning off deadlock detection. Please report this. ]\n\n");
- local_irq_disable();
-}
-
-/*
- * Recursively check for mutex deadlocks:
- */
-static int check_deadlock(struct mutex *lock, int depth,
- struct thread_info *ti, unsigned long ip)
-{
- struct mutex *lockblk;
- struct task_struct *task;
-
- if (!debug_mutex_on)
- return 0;
-
- ti = lock->owner;
- if (!ti)
- return 0;
-
- task = ti->task;
- lockblk = NULL;
- if (task->blocked_on)
- lockblk = task->blocked_on->lock;
-
- /* Self-deadlock: */
- if (current == task) {
- DEBUG_OFF();
- if (depth)
- return 1;
- printk("\n==========================================\n");
- printk( "[ BUG: lock recursion deadlock detected! |\n");
- printk( "------------------------------------------\n");
- report_deadlock(task, lock, NULL, ip);
- return 0;
- }
-
- /* Ugh, something corrupted the lock data structure? */
- if (depth > 20) {
- DEBUG_OFF();
- printk("\n===========================================\n");
- printk( "[ BUG: infinite lock dependency detected!? |\n");
- printk( "-------------------------------------------\n");
- report_deadlock(task, lock, lockblk, ip);
- return 0;
- }
-
- /* Recursively check for dependencies: */
- if (lockblk && check_deadlock(lockblk, depth+1, ti, ip)) {
- printk("\n============================================\n");
- printk( "[ BUG: circular locking deadlock detected! ]\n");
- printk( "--------------------------------------------\n");
- report_deadlock(task, lock, lockblk, ip);
- return 0;
- }
- return 0;
-}
-
-/*
- * Called when a task exits, this function checks whether the
- * task is holding any locks, and reports the first one if so:
- */
-void mutex_debug_check_no_locks_held(struct task_struct *task)
-{
- struct list_head *curr, *next;
- struct thread_info *t;
- unsigned long flags;
- struct mutex *lock;
-
- if (!debug_mutex_on)
- return;
-
- debug_spin_lock_save(&debug_mutex_lock, flags);
- list_for_each_safe(curr, next, &debug_mutex_held_locks) {
- lock = list_entry(curr, struct mutex, held_list);
- t = lock->owner;
- if (t != task->thread_info)
- continue;
- list_del_init(curr);
- DEBUG_OFF();
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
- printk("BUG: %s/%d, lock held at task exit time!\n",
- task->comm, task->pid);
- printk_lock(lock, 1);
- if (lock->owner != task->thread_info)
- printk("exiting task is not even the owner??\n");
- return;
- }
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
-}
-
-/*
- * Called when kernel memory is freed (or unmapped), or if a mutex
- * is destroyed or reinitialized - this code checks whether there is
- * any held lock in the memory range of <from> to <to>:
- */
-void mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
-{
- struct list_head *curr, *next;
- const void *to = from + len;
- unsigned long flags;
- struct mutex *lock;
- void *lock_addr;
-
- if (!debug_mutex_on)
- return;
-
- debug_spin_lock_save(&debug_mutex_lock, flags);
- list_for_each_safe(curr, next, &debug_mutex_held_locks) {
- lock = list_entry(curr, struct mutex, held_list);
- lock_addr = lock;
- if (lock_addr < from || lock_addr >= to)
- continue;
- list_del_init(curr);
- DEBUG_OFF();
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
- printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
- current->comm, current->pid, lock, from, to);
- dump_stack();
- printk_lock(lock, 1);
- if (lock->owner != current_thread_info())
- printk("freeing task is not even the owner??\n");
- return;
- }
- debug_spin_unlock_restore(&debug_mutex_lock, flags);
-}
-
/*
* Must be called with lock->wait_lock held.
*/
@@ -405,7 +90,6 @@ void debug_mutex_add_waiter(struct mutex
struct thread_info *ti __IP_DECL__)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
- check_deadlock(lock, 0, ti, ip);
/* Mark the current thread as blocked on the lock: */
ti->task->blocked_on = waiter;
waiter->lock = lock;
diff -puN lib/Kconfig.debug~lockdep-remove-mutex-deadlock-checking-code lib/Kconfig.debug
--- a/lib/Kconfig.debug~lockdep-remove-mutex-deadlock-checking-code
+++ a/lib/Kconfig.debug
@@ -115,14 +115,6 @@ config DEBUG_PREEMPT
if kernel code uses it in a preemption-unsafe way. Also, the kernel
will detect preemption count underflows.
-config DEBUG_MUTEXES
- bool "Mutex debugging, deadlock detection"
- default n
- depends on DEBUG_KERNEL
- help
- This allows mutex semantics violations and mutex related deadlocks
- (lockups) to be detected and reported automatically.
-
config DEBUG_RT_MUTEXES
bool "RT Mutex debugging, deadlock detection"
depends on DEBUG_KERNEL && RT_MUTEXES
_
Patches currently in -mm which might be from mingo@xxxxxxx are
origin.patch
disable-debugging-version-of-write_lock.patch
lock-validator-fix-ns83820c-irq-flags-bug.patch
revert-gregkh-pci-pci-test-that-drivers-properly-call-pci_set_master.patch
my-name-is-ingo-molnar-you-killed-my-make-allyesconfig-prepare-to-die.patch
sched-fix-bug-in-__migrate_task.patch
small-kernel-schedc-cleanup.patch
x86-re-enable-generic-numa.patch
sched-add-above-background-load-function.patch
mm-implement-swap-prefetching.patch
sched-cleanup-remove-task_t-convert-to-struct-task_struct-prefetch.patch
genirq-convert-the-x86_64-architecture-to-irq-chips.patch
genirq-convert-the-i386-architecture-to-irq-chips.patch
genirq-irq-convert-the-move_irq-flag-from-a-32bit-word-to-a-single-bit.patch
genirq-irq-add-moved_masked_irq.patch
genirq-x86_64-irq-reenable-migrating-irqs-to-other-cpus.patch
genirq-msi-simplify-msi-enable-and-disable.patch
genirq-msi-make-the-msi-boolean-tests-return-either-0-or-1.patch
genirq-msi-implement-helper-functions-read_msi_msg-and-write_msi_msg.patch
genirq-msi-refactor-the-msi_ops.patch
genirq-msi-simplify-the-msi-irq-limit-policy.patch
genirq-irq-add-a-dynamic-irq-creation-api.patch
genirq-ia64-irq-dynamic-irq-support.patch
genirq-i386-irq-dynamic-irq-support.patch
genirq-x86_64-irq-dynamic-irq-support.patch
genirq-msi-make-the-msi-code-irq-based-and-not-vector-based.patch
genirq-x86_64-irq-move-msi-message-composition-into-io_apicc.patch
genirq-i386-irq-move-msi-message-composition-into-io_apicc.patch
genirq-msi-only-build-msi-apicc-on-ia64.patch
genirq-x86_64-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-i386-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-irq-remove-msi-hacks.patch
genirq-irq-generalize-the-check-for-hardirq_bits.patch
genirq-x86_64-irq-make-the-external-irq-handlers-report-their-vector-not-the-irq-number.patch
genirq-x86_64-irq-make-vector_irq-per-cpu.patch
genirq-x86_64-irq-kill-gsi_irq_sharing.patch
genirq-x86_64-irq-kill-irq-compression.patch
detect-atomic-counter-underflows.patch
debug-shared-irqs.patch
make-frame_pointer-default=y.patch
mutex-subsystem-synchro-test-module.patch
vdso-print-fatal-signals.patch
vdso-improve-print_fatal_signals-support-by-adding-memory-maps.patch
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