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/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <skiboot.h>
#include <lock.h>
#include <assert.h>
#include <processor.h>
#include <cpu.h>
#include <console.h>
/* Set to bust locks. Note, this is initialized to true because our
* lock debugging code is not going to work until we have the per
* CPU data initialized
*/
bool bust_locks = true;
#ifdef DEBUG_LOCKS
static void lock_error(struct lock *l, const char *reason, uint16_t err)
{
bust_locks = true;
fprintf(stderr, "LOCK ERROR: %s @%p (state: 0x%016lx)\n",
reason, l, l->lock_val);
op_display(OP_FATAL, OP_MOD_LOCK, err);
abort();
}
static void lock_check(struct lock *l)
{
if ((l->lock_val & 1) && (l->lock_val >> 32) == this_cpu()->pir)
lock_error(l, "Invalid recursive lock", 0);
}
static void unlock_check(struct lock *l)
{
if (!(l->lock_val & 1))
lock_error(l, "Unlocking unlocked lock", 1);
if ((l->lock_val >> 32) != this_cpu()->pir)
lock_error(l, "Unlocked non-owned lock", 2);
if (l->in_con_path && this_cpu()->con_suspend == 0)
lock_error(l, "Unlock con lock with console not suspended", 3);
if (this_cpu()->lock_depth == 0)
lock_error(l, "Releasing lock with 0 depth", 4);
}
#else
static inline void lock_check(struct lock *l) { };
static inline void unlock_check(struct lock *l) { };
#endif /* DEBUG_LOCKS */
bool lock_held_by_me(struct lock *l)
{
uint64_t pir64 = this_cpu()->pir;
return l->lock_val == ((pir64 << 32) | 1);
}
bool try_lock(struct lock *l)
{
if (__try_lock(l)) {
if (l->in_con_path)
this_cpu()->con_suspend++;
this_cpu()->lock_depth++;
return true;
}
return false;
}
void lock(struct lock *l)
{
if (bust_locks)
return;
lock_check(l);
for (;;) {
if (try_lock(l))
break;
cpu_relax();
}
}
void unlock(struct lock *l)
{
struct cpu_thread *cpu = this_cpu();
if (bust_locks)
return;
unlock_check(l);
lwsync();
this_cpu()->lock_depth--;
l->lock_val = 0;
/* WARNING: On fast reboot, we can be reset right at that
* point, so the reset_lock in there cannot be in the con path
*/
if (l->in_con_path) {
cpu->con_suspend--;
if (cpu->con_suspend == 0 && cpu->con_need_flush)
flush_console();
}
}
bool lock_recursive(struct lock *l)
{
if (bust_locks)
return false;
if (lock_held_by_me(l))
return false;
lock(l);
return true;
}
void init_locks(void)
{
bust_locks = false;
}
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