Commit b0267507 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Ingo Molnar
Browse files

mutex: Avoid gcc version dependent __builtin_constant_p() usage 



Commit 040a0a37 ("mutex: Add support for wound/wait style locks")
used "!__builtin_constant_p(p == NULL)" but gcc 3.x cannot
handle such expression correctly, leading to boot failure when
built with CONFIG_DEBUG_MUTEXES=y.

Fix it by explicitly passing a bool which tells whether p != NULL
or not.

[ PeterZ: This is a sad patch, but provided it actually generates
          similar code I suppose its the best we can do bar whole
	  sale deprecating gcc-3. ]

Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: peterz@infradead.org
Cc: imirkin@alum.mit.edu
Cc: daniel.vetter@ffwll.ch
Cc: robdclark@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/201310171945.AGB17114.FSQVtHOJFOOFML@I-love.SAKURA.ne.jp


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 04919afb

kernel/mutex.c

+16 −16
Original line number Diff line number Diff line
@@ -410,7 +410,7 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, 
static __always_inline int __sched

__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,

		    struct lockdep_map *nest_lock, unsigned long ip,

		    struct ww_acquire_ctx *ww_ctx)

		    struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)

{

	struct task_struct *task = current;

	struct mutex_waiter waiter;
@@ -450,7 +450,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 
		struct task_struct *owner;

		struct mspin_node  node;



		if (!__builtin_constant_p(ww_ctx == NULL) && ww_ctx->acquired > 0) {

		if (use_ww_ctx && ww_ctx->acquired > 0) {

			struct ww_mutex *ww;



			ww = container_of(lock, struct ww_mutex, base);
@@ -480,7 +480,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 
		if ((atomic_read(&lock->count) == 1) &&

		    (atomic_cmpxchg(&lock->count, 1, 0) == 1)) {

			lock_acquired(&lock->dep_map, ip);

			if (!__builtin_constant_p(ww_ctx == NULL)) {

			if (use_ww_ctx) {

				struct ww_mutex *ww;

				ww = container_of(lock, struct ww_mutex, base);
@@ -551,7 +551,7 @@ slowpath: 
			goto err;

		}



		if (!__builtin_constant_p(ww_ctx == NULL) && ww_ctx->acquired > 0) {

		if (use_ww_ctx && ww_ctx->acquired > 0) {

			ret = __mutex_lock_check_stamp(lock, ww_ctx);

			if (ret)

				goto err;
@@ -575,7 +575,7 @@ skip_wait: 
	lock_acquired(&lock->dep_map, ip);

	mutex_set_owner(lock);



	if (!__builtin_constant_p(ww_ctx == NULL)) {

	if (use_ww_ctx) {

		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);

		struct mutex_waiter *cur;
@@ -615,7 +615,7 @@ mutex_lock_nested(struct mutex *lock, unsigned int subclass) 
{

	might_sleep();

	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,

			    subclass, NULL, _RET_IP_, NULL);

			    subclass, NULL, _RET_IP_, NULL, 0);

}



EXPORT_SYMBOL_GPL(mutex_lock_nested);
@@ -625,7 +625,7 @@ _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest) 
{

	might_sleep();

	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,

			    0, nest, _RET_IP_, NULL);

			    0, nest, _RET_IP_, NULL, 0);

}



EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
@@ -635,7 +635,7 @@ mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass) 
{

	might_sleep();

	return __mutex_lock_common(lock, TASK_KILLABLE,

				   subclass, NULL, _RET_IP_, NULL);

				   subclass, NULL, _RET_IP_, NULL, 0);

}

EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
@@ -644,7 +644,7 @@ mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) 
{

	might_sleep();

	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,

				   subclass, NULL, _RET_IP_, NULL);

				   subclass, NULL, _RET_IP_, NULL, 0);

}



EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
@@ -682,7 +682,7 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) 


	might_sleep();

	ret =  __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,

				   0, &ctx->dep_map, _RET_IP_, ctx);

				   0, &ctx->dep_map, _RET_IP_, ctx, 1);

	if (!ret && ctx->acquired > 1)

		return ww_mutex_deadlock_injection(lock, ctx);
@@ -697,7 +697,7 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) 


	might_sleep();

	ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,

				  0, &ctx->dep_map, _RET_IP_, ctx);

				  0, &ctx->dep_map, _RET_IP_, ctx, 1);



	if (!ret && ctx->acquired > 1)

		return ww_mutex_deadlock_injection(lock, ctx);
@@ -809,28 +809,28 @@ __mutex_lock_slowpath(atomic_t *lock_count) 
	struct mutex *lock = container_of(lock_count, struct mutex, count);



	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,

			    NULL, _RET_IP_, NULL);

			    NULL, _RET_IP_, NULL, 0);

}



static noinline int __sched

__mutex_lock_killable_slowpath(struct mutex *lock)

{

	return __mutex_lock_common(lock, TASK_KILLABLE, 0,

				   NULL, _RET_IP_, NULL);

				   NULL, _RET_IP_, NULL, 0);

}



static noinline int __sched

__mutex_lock_interruptible_slowpath(struct mutex *lock)

{

	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,

				   NULL, _RET_IP_, NULL);

				   NULL, _RET_IP_, NULL, 0);

}



static noinline int __sched

__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)

{

	return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,

				   NULL, _RET_IP_, ctx);

				   NULL, _RET_IP_, ctx, 1);

}



static noinline int __sched
@@ -838,7 +838,7 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock, 
					    struct ww_acquire_ctx *ctx)

{

	return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,

				   NULL, _RET_IP_, ctx);

				   NULL, _RET_IP_, ctx, 1);

}



#endif

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