/*
* Debugging versions of SMP locking primitives.
*
- * Copyright (C) 2004 Thibaut VARENE <varenet@esiee.fr>
+ * Copyright (C) 2004 Thibaut VARENE <varenet@parisc-linux.org>
*
* Some code stollen from alpha & sparc64 ;)
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * We use pdc_printf() throughout the file for all output messages, to avoid
+ * losing messages because of disabled interrupts. Since we're using these
+ * messages for debugging purposes, it makes sense not to send them to the
+ * linux console.
*/
#include <linux/spinlock.h>
#include <linux/hardirq.h> /* in_interrupt() */
#include <asm/system.h>
+#include <asm/hardirq.h> /* in_interrupt() */
+#include <asm/pdc.h>
#undef INIT_STUCK
#define INIT_STUCK 1L << 30
#ifdef CONFIG_DEBUG_SPINLOCK
+
void _dbg_spin_lock(spinlock_t * lock, const char *base_file, int line_no)
{
volatile unsigned int *a;
* <tausq> __ldcw() returns 1 if we get the lock; otherwise we
* spin until the value of the lock changes, or we time out.
*/
+ mb();
a = __ldcw_align(lock);
while (stuck && (__ldcw(a) == 0))
while ((*a == 0) && --stuck);
+ mb();
if (unlikely(stuck <= 0)) {
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: spin_lock(%s/%p) stuck in %s at %p(%d)"
" owned by %s:%d in %s at %p(%d)\n",
base_file, line_no, lock->module, lock,
lock->bline = line_no;
if (unlikely(printed)) {
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: spin_lock grabbed in %s at %p(%d) %ld ticks\n",
base_file, line_no, current->comm, inline_pc,
cpu, jiffies - started);
void _dbg_spin_unlock(spinlock_t * lock, const char *base_file, int line_no)
{
CHECK_LOCK(lock);
- volatile unsigned int *a = __ldcw_align(lock);
+ volatile unsigned int *a;
+ mb();
+ a = __ldcw_align(lock);
if (unlikely((*a != 0) && lock->babble)) {
lock->babble--;
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: spin_unlock(%s:%p) not locked\n",
base_file, line_no, lock->module, lock);
}
*a = 1;
+ mb();
}
int _dbg_spin_trylock(spinlock_t * lock, const char *base_file, int line_no)
{
int ret;
- volatile unsigned int *a = __ldcw_align(lock);
- if ((ret = (__ldcw(a) != 0))) {
+ volatile unsigned int *a;
+ mb();
+ a = __ldcw_align(lock);
+ ret = (__ldcw(a) != 0);
+ mb();
+ if (ret) {
lock->oncpu = smp_processor_id();
lock->previous = __builtin_return_address(0);
lock->task = current;
int cpu = smp_processor_id();
if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */
- printk(KERN_WARNING "write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline);
+ pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline);
BUG();
}
stuck--;
if ((unlikely(stuck <= 0)) && (rw->counter < 0)) {
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: write_lock stuck on writer"
" in %s at %p(%d) %ld ticks\n",
bfile, bline, current->comm, inline_pc,
printed = 1;
}
else if (unlikely(stuck <= 0)) {
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: write_lock stuck on reader"
" in %s at %p(%d) %ld ticks\n",
bfile, bline, current->comm, inline_pc,
rw->counter = -1; /* remember we are locked */
if (unlikely(printed)) {
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: write_lock grabbed in %s at %p(%d) %ld ticks\n",
bfile, bline, current->comm, inline_pc,
cpu, jiffies - started);
}
}
+int _dbg_write_trylock(rwlock_t *rw, const char *bfile, int bline)
+{
+#if 0
+ void *inline_pc = __builtin_return_address(0);
+ int cpu = smp_processor_id();
+#endif
+
+ if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */
+ pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline);
+ BUG();
+ }
+
+ /* Note: if interrupts are disabled (which is most likely), the printk
+ will never show on the console. We might need a polling method to flush
+ the dmesg buffer anyhow. */
+
+ _raw_spin_lock(&rw->lock);
+
+ if(rw->counter != 0) {
+ /* this basically never happens */
+ _raw_spin_unlock(&rw->lock);
+ return 0;
+ }
+
+ /* got it. now leave without unlocking */
+ rw->counter = -1; /* remember we are locked */
+#if 0
+ pdc_printf("%s:%d: try write_lock grabbed in %s at %p(%d)\n",
+ bfile, bline, current->comm, inline_pc, cpu);
+#endif
+ return 1;
+}
+
void _dbg_read_lock(rwlock_t * rw, const char *bfile, int bline)
{
#if 0
rw->counter++;
#if 0
- printk(KERN_WARNING
+ pdc_printf(
"%s:%d: read_lock grabbed in %s at %p(%d) %ld ticks\n",
bfile, bline, current->comm, inline_pc,
cpu, jiffies - started);