From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [patch 03/14] locking/rtmutex: Remove output from deadlock detector.
Date: Tue, 23 Mar 2021 22:30:22 +0100 [thread overview]
Message-ID: <20210323213707.773152524@linutronix.de> (raw)
In-Reply-To: 20210323213019.217008708@linutronix.de
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
The rtmutex specific deadlock detector predates lockdep coverage of rtmutex
and since commit f5694788ad8da ("rt_mutex: Add lockdep annotations") it
contains a lot of redundant functionality.
- lockdep will detect an potential deadlock before rtmutex-debug
has a chance to do so
- the dead lock debugging is restricted to rtmutexes which are not
associated to futexes and have an active waiter, which is covered by
lockdep already
Remove the redundant functionality and move actual deadlock WARN() into the
deadlock code path. The latter needs a seperate cleanup.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/rtmutex.h | 7 --
kernel/locking/rtmutex-debug.c | 97 ----------------------------------------
kernel/locking/rtmutex-debug.h | 9 ---
kernel/locking/rtmutex.c | 7 --
kernel/locking/rtmutex.h | 7 --
kernel/locking/rtmutex_common.h | 4 -
6 files changed, 1 insertion(+), 130 deletions(-)
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -31,9 +31,6 @@ struct rt_mutex {
raw_spinlock_t wait_lock;
struct rb_root_cached waiters;
struct task_struct *owner;
-#ifdef CONFIG_DEBUG_RT_MUTEXES
- const char *name;
-#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
@@ -56,8 +53,6 @@ struct hrtimer_sleeper;
#endif
#ifdef CONFIG_DEBUG_RT_MUTEXES
-# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
- , .name = #mutexname
# define rt_mutex_init(mutex) \
do { \
@@ -67,7 +62,6 @@ do { \
extern void rt_mutex_debug_task_free(struct task_struct *tsk);
#else
-# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
# define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL, NULL)
# define rt_mutex_debug_task_free(t) do { } while (0)
#endif
@@ -83,7 +77,6 @@ do { \
{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
, .waiters = RB_ROOT_CACHED \
, .owner = NULL \
- __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
__DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
#define DEFINE_RT_MUTEX(mutexname) \
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -32,105 +32,12 @@
#include "rtmutex_common.h"
-static void printk_task(struct task_struct *p)
-{
- if (p)
- printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
- else
- printk("<none>");
-}
-
-static void printk_lock(struct rt_mutex *lock, int print_owner)
-{
- printk(" [%p] {%s}\n", lock, lock->name);
-
- if (print_owner && rt_mutex_owner(lock)) {
- printk(".. ->owner: %p\n", lock->owner);
- printk(".. held by: ");
- printk_task(rt_mutex_owner(lock));
- printk("\n");
- }
-}
-
void rt_mutex_debug_task_free(struct task_struct *task)
{
DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
}
-/*
- * We fill out the fields in the waiter to store the information about
- * the deadlock. We print when we return. act_waiter can be NULL in
- * case of a remove waiter operation.
- */
-void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
- struct rt_mutex_waiter *act_waiter,
- struct rt_mutex *lock)
-{
- struct task_struct *task;
-
- if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
- return;
-
- task = rt_mutex_owner(act_waiter->lock);
- if (task && task != current) {
- act_waiter->deadlock_task_pid = get_pid(task_pid(task));
- act_waiter->deadlock_lock = lock;
- }
-}
-
-void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
-{
- struct task_struct *task;
-
- if (!waiter->deadlock_lock || !debug_locks)
- return;
-
- rcu_read_lock();
- task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
- if (!task) {
- rcu_read_unlock();
- return;
- }
-
- if (!debug_locks_off()) {
- rcu_read_unlock();
- return;
- }
-
- pr_warn("\n");
- pr_warn("============================================\n");
- pr_warn("WARNING: circular locking deadlock detected!\n");
- pr_warn("%s\n", print_tainted());
- pr_warn("--------------------------------------------\n");
- printk("%s/%d is deadlocking current task %s/%d\n\n",
- task->comm, task_pid_nr(task),
- current->comm, task_pid_nr(current));
-
- printk("\n1) %s/%d is trying to acquire this lock:\n",
- current->comm, task_pid_nr(current));
- printk_lock(waiter->lock, 1);
-
- printk("\n2) %s/%d is blocked on this lock:\n",
- task->comm, task_pid_nr(task));
- printk_lock(waiter->deadlock_lock, 1);
-
- debug_show_held_locks(current);
- debug_show_held_locks(task);
-
- printk("\n%s/%d's [blocked] stackdump:\n\n",
- task->comm, task_pid_nr(task));
- show_stack(task, NULL, KERN_DEFAULT);
- printk("\n%s/%d's [current] stackdump:\n\n",
- current->comm, task_pid_nr(current));
- dump_stack();
- debug_show_all_locks();
- rcu_read_unlock();
-
- printk("[ turning off deadlock detection."
- "Please report this trace. ]\n\n");
-}
-
void debug_rt_mutex_lock(struct rt_mutex *lock)
{
}
@@ -153,12 +60,10 @@ void debug_rt_mutex_proxy_unlock(struct
void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
memset(waiter, 0x11, sizeof(*waiter));
- waiter->deadlock_task_pid = NULL;
}
void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
{
- put_pid(waiter->deadlock_task_pid);
memset(waiter, 0x22, sizeof(*waiter));
}
@@ -168,10 +73,8 @@ void debug_rt_mutex_init(struct rt_mutex
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lock->name = name;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_init_map(&lock->dep_map, name, key, 0);
#endif
}
-
--- a/kernel/locking/rtmutex-debug.h
+++ b/kernel/locking/rtmutex-debug.h
@@ -18,18 +18,9 @@ extern void debug_rt_mutex_unlock(struct
extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
struct task_struct *powner);
extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
-extern void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
- struct rt_mutex_waiter *waiter,
- struct rt_mutex *lock);
-extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
enum rtmutex_chainwalk walk)
{
return (waiter != NULL);
}
-
-static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
-{
- debug_rt_mutex_print_deadlock(w);
-}
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -579,7 +579,6 @@ static int rt_mutex_adjust_prio_chain(st
* walk, we detected a deadlock.
*/
if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
- debug_rt_mutex_deadlock(chwalk, orig_waiter, lock);
raw_spin_unlock(&lock->wait_lock);
ret = -EDEADLK;
goto out_unlock_pi;
@@ -1171,8 +1170,6 @@ static int __sched
raw_spin_unlock_irq(&lock->wait_lock);
- debug_rt_mutex_print_deadlock(waiter);
-
schedule();
raw_spin_lock_irq(&lock->wait_lock);
@@ -1196,7 +1193,7 @@ static void rt_mutex_handle_deadlock(int
/*
* Yell loudly and stop the task right here.
*/
- rt_mutex_print_deadlock(w);
+ WARN(1, "rtmutex deadlock detected\n");
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
@@ -1704,8 +1701,6 @@ int __rt_mutex_start_proxy_lock(struct r
ret = 0;
}
- debug_rt_mutex_print_deadlock(waiter);
-
return ret;
}
--- a/kernel/locking/rtmutex.h
+++ b/kernel/locking/rtmutex.h
@@ -18,13 +18,6 @@
#define debug_rt_mutex_proxy_unlock(l) do { } while (0)
#define debug_rt_mutex_unlock(l) do { } while (0)
#define debug_rt_mutex_init(m, n, k) do { } while (0)
-#define debug_rt_mutex_deadlock(d, a ,l) do { } while (0)
-#define debug_rt_mutex_print_deadlock(w) do { } while (0)
-
-static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
-{
- WARN(1, "rtmutex deadlock detected\n");
-}
static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *w,
enum rtmutex_chainwalk walk)
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -29,10 +29,6 @@ struct rt_mutex_waiter {
struct rb_node pi_tree_entry;
struct task_struct *task;
struct rt_mutex *lock;
-#ifdef CONFIG_DEBUG_RT_MUTEXES
- struct pid *deadlock_task_pid;
- struct rt_mutex *deadlock_lock;
-#endif
int prio;
u64 deadline;
};
next prev parent reply other threads:[~2021-03-23 21:41 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 21:30 [patch 00/14] locking/rtmutex: Spring cleaning Thomas Gleixner
2021-03-23 21:30 ` [patch 01/14] locking/rtmutex: Remove rt_mutex_timed_lock() Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-03-23 21:30 ` [patch 02/14] locking/rtmutex: Remove rtmutex deadlock tester leftovers Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-03-23 21:30 ` Thomas Gleixner [this message]
2021-03-24 7:22 ` [tip: locking/core] locking/rtmutex: Remove output from deadlock detector tip-bot2 for Sebastian Andrzej Siewior
2021-03-23 21:30 ` [patch 04/14] locking/rtmutex: Consolidate rt_mutex_init() Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-03-23 21:30 ` [patch 05/14] locking/rtmutex: Remove empty and unused debug stubs Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 06/14] locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 07/14] locking/rtmutex: Inline chainwalk depth check Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 08/14] locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 09/14] locking/rtmutex: Decrapify __rt_mutex_init() Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 10/14] locking/rtmutex: Move debug functions as inlines into common header Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 11/14] locking/rtmutex: Make text section and inlining consistent Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 12/14] locking/rtmutex: Consolidate the fast/slowpath invocation Thomas Gleixner
2021-03-23 22:05 ` Thomas Gleixner
2021-03-23 21:30 ` [patch 13/14] locking/rtmutex: Fix misleading comment in rt_mutex_postunlock() Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:30 ` [patch 14/14] locking/rtmutex: Restrict the trylock WARN_ON() to debug Thomas Gleixner
2021-03-24 7:22 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-03-23 21:47 ` [patch 00/14] locking/rtmutex: Spring cleaning Thomas Gleixner
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