From: Peter Zijlstra <peterz@infradead.org>
To: Byungchul Park <byungchul.park@lge.com>
Cc: mingo@kernel.org, tglx@linutronix.de, walken@google.com,
boqun.feng@gmail.com, kirill@shutemov.name,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, willy@infradead.org,
npiggin@gmail.com, kernel-team@lge.com
Subject: Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions
Date: Wed, 9 Aug 2017 12:24:39 +0200 [thread overview]
Message-ID: <20170809102439.7ze32yrua4ieyswe@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20170809095107.2nzb4m4wq2p77ppb@hirez.programming.kicks-ass.net>
On Wed, Aug 09, 2017 at 11:51:07AM +0200, Peter Zijlstra wrote:
> On Mon, Aug 07, 2017 at 04:12:56PM +0900, Byungchul Park wrote:
> > +static inline void wait_for_completion(struct completion *x)
> > +{
> > + complete_acquire(x);
> > + __wait_for_completion(x);
> > + complete_release(x);
> > +}
> > +
> > +static inline void wait_for_completion_io(struct completion *x)
> > +{
> > + complete_acquire(x);
> > + __wait_for_completion_io(x);
> > + complete_release(x);
> > +}
> > +
> > +static inline int wait_for_completion_interruptible(struct completion *x)
> > +{
> > + int ret;
> > + complete_acquire(x);
> > + ret = __wait_for_completion_interruptible(x);
> > + complete_release(x);
> > + return ret;
> > +}
> > +
> > +static inline int wait_for_completion_killable(struct completion *x)
> > +{
> > + int ret;
> > + complete_acquire(x);
> > + ret = __wait_for_completion_killable(x);
> > + complete_release(x);
> > + return ret;
> > +}
>
> I don't understand, why not change __wait_for_common() ?
That is what is wrong with the below?
Yes, it adds acquire/release to the timeout variants too, but I don't
see why we should exclude those, and even if we'd want to do that, it
would be trivial:
bool timo = (timeout == MAX_SCHEDULE_TIMEOUT);
if (!timo)
complete_acquire(x);
/* ... */
if (!timo)
complete_release(x);
But like said, I think we very much want to annotate waits with timeouts
too. Hitting the max timo doesn't necessarily mean we'll make fwd
progress, we could be stuck in a loop doing something else again before
returning to wait.
Also, even if we'd make fwd progress, hitting that max timo is still not
desirable.
---
Subject: lockdep: Apply crossrelease to completions
From: Byungchul Park <byungchul.park@lge.com>
Date: Mon, 7 Aug 2017 16:12:56 +0900
Although wait_for_completion() and its family can cause deadlock, the
lock correctness validator could not be applied to them until now,
because things like complete() are usually called in a different context
from the waiting context, which violates lockdep's assumption.
Thanks to CONFIG_LOCKDEP_CROSSRELEASE, we can now apply the lockdep
detector to those completion operations. Applied it.
Cc: npiggin@gmail.com
Cc: mingo@kernel.org
Cc: akpm@linux-foundation.org
Cc: tglx@linutronix.de
Cc: boqun.feng@gmail.com
Cc: willy@infradead.org
Cc: walken@google.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/completion.h | 45 ++++++++++++++++++++++++++++++++++++++++++++-
kernel/sched/completion.c | 11 +++++++++++
lib/Kconfig.debug | 8 ++++++++
3 files changed, 63 insertions(+), 1 deletion(-)
--- a/include/linux/completion.h
+++ b/include/linux/completion.h
@@ -9,6 +9,9 @@
*/
#include <linux/wait.h>
+#ifdef CONFIG_LOCKDEP_COMPLETE
+#include <linux/lockdep.h>
+#endif
/*
* struct completion - structure used to maintain state for a "completion"
@@ -25,10 +28,50 @@
struct completion {
unsigned int done;
wait_queue_head_t wait;
+#ifdef CONFIG_LOCKDEP_COMPLETE
+ struct lockdep_map_cross map;
+#endif
};
+#ifdef CONFIG_LOCKDEP_COMPLETE
+static inline void complete_acquire(struct completion *x)
+{
+ lock_acquire_exclusive((struct lockdep_map *)&x->map, 0, 0, NULL, _RET_IP_);
+}
+
+static inline void complete_release(struct completion *x)
+{
+ lock_release((struct lockdep_map *)&x->map, 0, _RET_IP_);
+}
+
+static inline void complete_release_commit(struct completion *x)
+{
+ lock_commit_crosslock((struct lockdep_map *)&x->map);
+}
+
+#define init_completion(x) \
+do { \
+ static struct lock_class_key __key; \
+ lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \
+ "(complete)" #x, \
+ &__key, 0); \
+ __init_completion(x); \
+} while (0)
+#else
+#define init_completion(x) __init_completion(x)
+static inline void complete_acquire(struct completion *x) {}
+static inline void complete_release(struct completion *x) {}
+static inline void complete_release_commit(struct completion *x) {}
+#endif
+
+#ifdef CONFIG_LOCKDEP_COMPLETE
+#define COMPLETION_INITIALIZER(work) \
+ { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait), \
+ STATIC_CROSS_LOCKDEP_MAP_INIT("(complete)" #work, &(work)) }
+#else
#define COMPLETION_INITIALIZER(work) \
{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
+#endif
#define COMPLETION_INITIALIZER_ONSTACK(work) \
({ init_completion(&work); work; })
@@ -70,7 +113,7 @@ struct completion {
* This inline function will initialize a dynamically created completion
* structure.
*/
-static inline void init_completion(struct completion *x)
+static inline void __init_completion(struct completion *x)
{
x->done = 0;
init_waitqueue_head(&x->wait);
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -32,6 +32,12 @@ void complete(struct completion *x)
unsigned long flags;
spin_lock_irqsave(&x->wait.lock, flags);
+
+ /*
+ * Perform commit of crossrelease here.
+ */
+ complete_release_commit(x);
+
if (x->done != UINT_MAX)
x->done++;
__wake_up_locked(&x->wait, TASK_NORMAL, 1);
@@ -92,9 +98,14 @@ __wait_for_common(struct completion *x,
{
might_sleep();
+ complete_acquire(x);
+
spin_lock_irq(&x->wait.lock);
timeout = do_wait_for_common(x, action, timeout, state);
spin_unlock_irq(&x->wait.lock);
+
+ complete_release(x);
+
return timeout;
}
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1085,6 +1085,14 @@ config LOCKDEP_CROSSRELEASE
such as page locks or completions can use the lock correctness
detector, lockdep.
+config LOCKDEP_COMPLETE
+ bool "Lock debugging: allow completions to use deadlock detector"
+ select LOCKDEP_CROSSRELEASE
+ default n
+ help
+ A deadlock caused by wait_for_completion() and complete() can be
+ detected by lockdep using crossrelease feature.
+
config PROVE_LOCKING
bool "Lock debugging: prove locking correctness"
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
next prev parent reply other threads:[~2017-08-09 10:24 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 7:12 [PATCH v8 00/14] lockdep: Implement crossrelease feature Byungchul Park
2017-08-07 7:12 ` [PATCH v8 01/14] lockdep: Refactor lookup_chain_cache() Byungchul Park
2017-08-10 12:18 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 02/14] lockdep: Add a function building a chain between two classes Byungchul Park
2017-08-10 12:18 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 03/14] lockdep: Change the meaning of check_prev_add()'s return value Byungchul Park
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 04/14] lockdep: Make check_prev_add() able to handle external stack_trace Byungchul Park
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 05/14] lockdep: Implement crossrelease feature Byungchul Park
2017-08-09 14:05 ` Peter Zijlstra
2017-08-10 1:30 ` Byungchul Park
2017-08-10 9:21 ` Peter Zijlstra
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: Implement the 'crossrelease' feature tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 06/14] lockdep: Detect and handle hist_lock ring buffer overwrite Byungchul Park
2017-08-09 14:16 ` Peter Zijlstra
2017-08-10 1:32 ` Byungchul Park
2017-08-10 9:22 ` Peter Zijlstra
2017-08-10 10:32 ` Byungchul Park
2017-08-10 11:59 ` Boqun Feng
2017-08-10 12:11 ` Byungchul Park
2017-08-10 12:51 ` Boqun Feng
2017-08-10 13:17 ` Boqun Feng
2017-08-11 0:44 ` Byungchul Park
2017-08-11 3:43 ` Byungchul Park
2017-08-11 8:03 ` Boqun Feng
2017-08-11 8:52 ` Byungchul Park
2017-08-11 9:44 ` Byungchul Park
2017-08-11 13:06 ` Byungchul Park
2017-08-14 7:05 ` Boqun Feng
2017-08-14 7:22 ` Byungchul Park
2017-08-14 7:29 ` Byungchul Park
2017-08-11 0:40 ` Byungchul Park
2017-08-11 1:03 ` Boqun Feng
2017-08-10 12:20 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 07/14] lockdep: Handle non(or multi)-acquisition of a crosslock Byungchul Park
2017-08-10 12:20 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 08/14] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park
2017-08-10 12:21 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 09/14] lockdep: Apply crossrelease to completions Byungchul Park
2017-08-07 10:20 ` kbuild test robot
2017-08-07 11:45 ` kbuild test robot
2017-08-09 9:51 ` Peter Zijlstra
2017-08-09 10:24 ` Peter Zijlstra [this message]
2017-08-10 1:24 ` Byungchul Park
2017-08-10 12:21 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-14 8:50 ` [PATCH v8 09/14] lockdep: " Arnd Bergmann
2017-08-18 23:43 ` Boqun Feng
2017-08-19 12:51 ` Arnd Bergmann
2017-08-19 13:34 ` Arnd Bergmann
2017-08-23 14:43 ` Boqun Feng
2017-08-20 3:18 ` Boqun Feng
2017-08-07 7:12 ` [PATCH v8 10/14] pagemap.h: Remove trailing white space Byungchul Park
2017-08-07 7:12 ` [PATCH v8 11/14] lockdep: Apply crossrelease to PG_locked locks Byungchul Park
2017-08-07 10:36 ` kbuild test robot
2017-08-10 1:35 ` Byungchul Park
2017-08-10 9:25 ` Peter Zijlstra
2017-09-05 1:03 ` Byungchul Park
2017-08-07 7:12 ` [PATCH v8 12/14] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2017-08-07 7:13 ` [PATCH v8 13/14] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2017-08-07 10:43 ` kbuild test robot
2017-08-07 7:13 ` [PATCH v8 14/14] lockdep: Crossrelease feature documentation Byungchul Park
2017-08-07 15:58 ` kbuild test robot
2017-08-10 12:22 ` [tip:locking/core] locking/lockdep: Add 'crossrelease' " tip-bot for Byungchul Park
2017-08-09 15:50 ` [PATCH v8 00/14] lockdep: Implement crossrelease feature Peter Zijlstra
2017-08-10 0:55 ` Byungchul Park
2017-08-10 3:47 ` Byungchul Park
2017-08-10 10:52 ` Byungchul Park
2017-08-10 9:37 ` Byungchul Park
2017-08-10 10:52 ` Peter Zijlstra
2017-08-10 11:10 ` Ingo Molnar
2017-08-10 11:45 ` Byungchul Park
2017-08-14 10:57 ` Ingo Molnar
2017-08-14 11:10 ` Byungchul Park
2017-08-15 8:20 ` Ingo Molnar
2017-08-16 0:16 ` Byungchul Park
2017-08-16 4:05 ` Boqun Feng
2017-08-16 4:37 ` Byungchul Park
2017-08-16 5:40 ` Boqun Feng
2017-08-16 6:37 ` Byungchul Park
2017-08-16 5:05 ` Byungchul Park
2017-08-16 5:58 ` Boqun Feng
2017-08-16 7:14 ` Byungchul Park
2017-08-16 8:06 ` Byungchul Park
2017-08-16 9:38 ` Byungchul Park
2017-08-17 7:48 ` Ingo Molnar
2017-08-17 8:04 ` Boqun Feng
2017-08-17 8:12 ` Ingo Molnar
2017-08-17 8:33 ` Boqun Feng
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