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- Don't panic on a try lock operation for a sleep lock if we hold a spin

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lock.  Since we won't actually block on a try lock operation, it's not
  a problem.  Add a comment explaining why it is safe to skip lock order
  checking with try locks.
- Remove the ithread list lock spin lock from the order list.
This commit is contained in:
John Baldwin 2001-05-17 22:44:56 +00:00
parent 4d29cb2db9
commit 1ad5401134
1 changed files with 6 additions and 2 deletions
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8
sys/kern/subr_witness.c
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@ -207,7 +207,6 @@ static struct witness_order_list_entry order_lists[] = {
{ "ng_node", &lock_class_mtx_spin },
{ "ng_worklist", &lock_class_mtx_spin },
{ "ithread table lock", &lock_class_mtx_spin },
{ "ithread list lock", &lock_class_mtx_spin },
{ "sched lock", &lock_class_mtx_spin },
{ "clk", &lock_class_mtx_spin },
{ "callout", &lock_class_mtx_spin },
@ -485,7 +484,7 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
mtx_lock_spin(&w_mtx);
lock_list = PCPU_PTR(spinlocks);
if (class->lc_flags & LC_SLEEPLOCK) {
if (*lock_list != NULL) {
if (*lock_list != NULL && (flags & LOP_TRYLOCK) == 0) {
mtx_unlock_spin(&w_mtx);
panic("blockable sleep lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
@ -494,6 +493,11 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
}
mtx_unlock_spin(&w_mtx);
/*
* Try locks do not block if they fail to acquire the lock, thus
* there is no danger of deadlocks or of switching while holding a
* spin lock if we acquire a lock via a try operation.
*/
if (flags & LOP_TRYLOCK)
goto out;