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Add a new function to look for a spinlock's instance when it is held by

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another thread.  We use the td_oncpu member of the other field to locate
it's associated CPU and then search the that CPU's list of spin locks
contained in its per-CPU data.  This is not always safe and may in fact
panic or just not work, but it is useful in at least one case.
This commit is contained in:
jhb 2003-07-31 18:50:58 +00:00
parent cc461cb6e3
commit a3b9c0d553
2 changed files with 22 additions and 0 deletions
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21
sys/kern/subr_witness.c
View File

@ -1593,6 +1593,27 @@ witness_list_locks(struct lock_list_entry **lock_list)
return (nheld);
}
/*
* This is a bit risky at best. We call this function when we have timed
* out acquiring a spin lock, and we assume that the other CPU is stuck
* with this lock held. So, we go groveling around in the other CPU's
* per-cpu data to try to find the lock instance for this spin lock to
* see when it was last acquired.
*/
void
witness_display_spinlock(struct lock_object *lock, struct thread *owner)
{
struct lock_instance *instance;
struct pcpu *pc;
if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
return;
pc = pcpu_find(owner->td_oncpu);
instance = find_instance(pc->pc_spinlocks, lock);
if (instance != NULL)
witness_list_lock(instance);
}
void
witness_save(struct lock_object *lock, const char **filep, int *linep)
{

1
sys/sys/lock.h
View File

@ -206,6 +206,7 @@ void witness_restore(struct lock_object *, const char *, int);
int witness_list_locks(struct lock_list_entry **);
int witness_warn(int, struct lock_object *, const char *, ...);
void witness_assert(struct lock_object *, int, const char *, int);
void witness_display_spinlock(struct lock_object *, struct thread *);
int witness_line(struct lock_object *);
const char *witness_file(struct lock_object *);