3434#include <linux/spinlock.h>
3535#include <linux/ftrace.h>
3636#include <trace/events/lock.h>
37+ #include <linux/hung_task.h>
3738
3839static noinline void __down (struct semaphore * sem );
3940static noinline int __down_interruptible (struct semaphore * sem );
4041static noinline int __down_killable (struct semaphore * sem );
4142static noinline int __down_timeout (struct semaphore * sem , long timeout );
4243static noinline void __up (struct semaphore * sem , struct wake_q_head * wake_q );
4344
45+ #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
46+ static inline void hung_task_sem_set_holder (struct semaphore * sem )
47+ {
48+ WRITE_ONCE ((sem )-> last_holder , (unsigned long )current );
49+ }
50+
51+ static inline void hung_task_sem_clear_if_holder (struct semaphore * sem )
52+ {
53+ if (READ_ONCE ((sem )-> last_holder ) == (unsigned long )current )
54+ WRITE_ONCE ((sem )-> last_holder , 0UL );
55+ }
56+
57+ unsigned long sem_last_holder (struct semaphore * sem )
58+ {
59+ return READ_ONCE (sem -> last_holder );
60+ }
61+ #else
62+ static inline void hung_task_sem_set_holder (struct semaphore * sem )
63+ {
64+ }
65+ static inline void hung_task_sem_clear_if_holder (struct semaphore * sem )
66+ {
67+ }
68+ unsigned long sem_last_holder (struct semaphore * sem )
69+ {
70+ return 0UL ;
71+ }
72+ #endif
73+
74+ static inline void __sem_acquire (struct semaphore * sem )
75+ {
76+ sem -> count -- ;
77+ hung_task_sem_set_holder (sem );
78+ }
79+
4480/**
4581 * down - acquire the semaphore
4682 * @sem: the semaphore to be acquired
@@ -59,7 +95,7 @@ void __sched down(struct semaphore *sem)
5995 might_sleep ();
6096 raw_spin_lock_irqsave (& sem -> lock , flags );
6197 if (likely (sem -> count > 0 ))
62- sem -> count -- ;
98+ __sem_acquire ( sem ) ;
6399 else
64100 __down (sem );
65101 raw_spin_unlock_irqrestore (& sem -> lock , flags );
@@ -83,7 +119,7 @@ int __sched down_interruptible(struct semaphore *sem)
83119 might_sleep ();
84120 raw_spin_lock_irqsave (& sem -> lock , flags );
85121 if (likely (sem -> count > 0 ))
86- sem -> count -- ;
122+ __sem_acquire ( sem ) ;
87123 else
88124 result = __down_interruptible (sem );
89125 raw_spin_unlock_irqrestore (& sem -> lock , flags );
@@ -110,7 +146,7 @@ int __sched down_killable(struct semaphore *sem)
110146 might_sleep ();
111147 raw_spin_lock_irqsave (& sem -> lock , flags );
112148 if (likely (sem -> count > 0 ))
113- sem -> count -- ;
149+ __sem_acquire ( sem ) ;
114150 else
115151 result = __down_killable (sem );
116152 raw_spin_unlock_irqrestore (& sem -> lock , flags );
@@ -140,7 +176,7 @@ int __sched down_trylock(struct semaphore *sem)
140176 raw_spin_lock_irqsave (& sem -> lock , flags );
141177 count = sem -> count - 1 ;
142178 if (likely (count >= 0 ))
143- sem -> count = count ;
179+ __sem_acquire ( sem ) ;
144180 raw_spin_unlock_irqrestore (& sem -> lock , flags );
145181
146182 return (count < 0 );
@@ -165,7 +201,7 @@ int __sched down_timeout(struct semaphore *sem, long timeout)
165201 might_sleep ();
166202 raw_spin_lock_irqsave (& sem -> lock , flags );
167203 if (likely (sem -> count > 0 ))
168- sem -> count -- ;
204+ __sem_acquire ( sem ) ;
169205 else
170206 result = __down_timeout (sem , timeout );
171207 raw_spin_unlock_irqrestore (& sem -> lock , flags );
@@ -187,6 +223,9 @@ void __sched up(struct semaphore *sem)
187223 DEFINE_WAKE_Q (wake_q );
188224
189225 raw_spin_lock_irqsave (& sem -> lock , flags );
226+
227+ hung_task_sem_clear_if_holder (sem );
228+
190229 if (likely (list_empty (& sem -> wait_list )))
191230 sem -> count ++ ;
192231 else
@@ -228,8 +267,10 @@ static inline int __sched ___down_common(struct semaphore *sem, long state,
228267 raw_spin_unlock_irq (& sem -> lock );
229268 timeout = schedule_timeout (timeout );
230269 raw_spin_lock_irq (& sem -> lock );
231- if (waiter .up )
270+ if (waiter .up ) {
271+ hung_task_sem_set_holder (sem );
232272 return 0 ;
273+ }
233274 }
234275
235276 timed_out :
@@ -246,10 +287,14 @@ static inline int __sched __down_common(struct semaphore *sem, long state,
246287{
247288 int ret ;
248289
290+ hung_task_set_blocker (sem , BLOCKER_TYPE_SEM );
291+
249292 trace_contention_begin (sem , 0 );
250293 ret = ___down_common (sem , state , timeout );
251294 trace_contention_end (sem , ret );
252295
296+ hung_task_clear_blocker ();
297+
253298 return ret ;
254299}
255300
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