[xen master] xen/rwlock: add check_lock() handling to rwlocks

[patchbot@xxxxxxx]

commit e19bcb626f50a652fb1854a8b2f2c9c371687a11
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Fri Nov 6 10:48:07 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Nov 6 10:48:07 2020 +0100

    xen/rwlock: add check_lock() handling to rwlocks
    
    Checking whether a lock is consistently used regarding interrupts on
    or off is beneficial for rwlocks, too.
    
    So add check_lock() calls to rwlock functions. For this purpose make
    check_lock() globally accessible.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/common/spinlock.c      |  3 +--
 xen/include/xen/rwlock.h   | 15 +++++++++++++++
 xen/include/xen/spinlock.h |  2 ++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index f4eb50f030..b90981bb27 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -13,7 +13,7 @@
 
 static atomic_t spin_debug __read_mostly = ATOMIC_INIT(0);
 
-static void check_lock(union lock_debug *debug, bool try)
+void check_lock(union lock_debug *debug, bool try)
 {
     bool irq_safe = !local_irq_is_enabled();
 
@@ -108,7 +108,6 @@ void spin_debug_disable(void)
 
 #else /* CONFIG_DEBUG_LOCKS */
 
-#define check_lock(l, t) ((void)0)
 #define check_barrier(l) ((void)0)
 #define got_lock(l) ((void)0)
 #define rel_lock(l) ((void)0)
diff --git a/xen/include/xen/rwlock.h b/xen/include/xen/rwlock.h
index 427664037a..0cc9167715 100644
--- a/xen/include/xen/rwlock.h
+++ b/xen/include/xen/rwlock.h
@@ -56,6 +56,7 @@ static inline int _read_trylock(rwlock_t *lock)
     u32 cnts;
 
     preempt_disable();
+    check_lock(&lock->lock.debug, true);
     cnts = atomic_read(&lock->cnts);
     if ( likely(_can_read_lock(cnts)) )
     {
@@ -87,7 +88,11 @@ static inline void _read_lock(rwlock_t *lock)
      * arch_lock_acquire_barrier().
      */
     if ( likely(_can_read_lock(cnts)) )
+    {
+        /* The slow path calls check_lock() via spin_lock(). */
+        check_lock(&lock->lock.debug, false);
         return;
+    }
 
     /* The slowpath will decrement the reader count, if necessary. */
     queue_read_lock_slowpath(lock);
@@ -162,7 +167,11 @@ static inline void _write_lock(rwlock_t *lock)
      * arch_lock_acquire_barrier().
      */
     if ( atomic_cmpxchg(&lock->cnts, 0, _write_lock_val()) == 0 )
+    {
+        /* The slow path calls check_lock() via spin_lock(). */
+        check_lock(&lock->lock.debug, false);
         return;
+    }
 
     queue_write_lock_slowpath(lock);
     /*
@@ -197,6 +206,7 @@ static inline int _write_trylock(rwlock_t *lock)
     u32 cnts;
 
     preempt_disable();
+    check_lock(&lock->lock.debug, true);
     cnts = atomic_read(&lock->cnts);
     if ( unlikely(cnts) ||
          unlikely(atomic_cmpxchg(&lock->cnts, 0, _write_lock_val()) != 0) )
@@ -328,6 +338,11 @@ static inline void _percpu_read_lock(percpu_rwlock_t 
**per_cpudata,
         /* Drop the read lock because we don't need it anymore. */
         read_unlock(&percpu_rwlock->rwlock);
     }
+    else
+    {
+        /* All other paths have implicit check_lock() calls via read_lock(). */
+        check_lock(&percpu_rwlock->rwlock.lock.debug, false);
+    }
 }
 
 static inline void _percpu_read_unlock(percpu_rwlock_t **per_cpudata,
diff --git a/xen/include/xen/spinlock.h b/xen/include/xen/spinlock.h
index ca13b600a0..9fa4e600c1 100644
--- a/xen/include/xen/spinlock.h
+++ b/xen/include/xen/spinlock.h
@@ -21,11 +21,13 @@ union lock_debug {
     };
 };
 #define _LOCK_DEBUG { LOCK_DEBUG_INITVAL }
+void check_lock(union lock_debug *debug, bool try);
 void spin_debug_enable(void);
 void spin_debug_disable(void);
 #else
 union lock_debug { };
 #define _LOCK_DEBUG { }
+#define check_lock(l, t) ((void)0)
 #define spin_debug_enable() ((void)0)
 #define spin_debug_disable() ((void)0)
 #endif
--
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