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[MIPS] SMTC: Fix recursion in instant IPI replay code.

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local_irq_restore -> raw_local_irq_restore -> irq_restore_epilog ->
	smtc_ipi_replay -> smtc_ipi_dq -> spin_unlock_irqrestore ->
	_spin_unlock_irqrestore -> local_irq_restore

The recursion does abort when there is no more IPI queued for a CPU, so
this isn't usually fatal which is why we got away with this for so long
until this was discovered by code inspection.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle
2007-03-29 23:42:42 +01:00
parent 6c9fde4bff
commit 8a1e97ee2e
3 changed files with 69 additions and 42 deletions
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40
arch/mips/kernel/smtc.c
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@@ -999,10 +999,17 @@ static void setup_cross_vpe_interrupts(unsigned int nvpe)
/*
* SMTC-specific hacks invoked from elsewhere in the kernel.
*
* smtc_ipi_replay is called from raw_local_irq_restore which is only ever
* called with interrupts disabled. We do rely on interrupts being disabled
* here because using spin_lock_irqsave()/spin_unlock_irqrestore() would
* result in a recursive call to raw_local_irq_restore().
*/
void smtc_ipi_replay(void)
static void __smtc_ipi_replay(void)
{
unsigned int cpu = smp_processor_id();
/*
* To the extent that we've ever turned interrupts off,
* we may have accumulated deferred IPIs. This is subtle.
@@ -1017,17 +1024,30 @@ void smtc_ipi_replay(void)
* is clear, and we'll handle it as a real pseudo-interrupt
* and not a pseudo-pseudo interrupt.
*/
if (IPIQ[smp_processor_id()].depth > 0) {
struct smtc_ipi *pipi;
extern void self_ipi(struct smtc_ipi *);
if (IPIQ[cpu].depth > 0) {
while (1) {
struct smtc_ipi_q *q = &IPIQ[cpu];
struct smtc_ipi *pipi;
extern void self_ipi(struct smtc_ipi *);
spin_lock(&q->lock);
pipi = __smtc_ipi_dq(q);
spin_unlock(&q->lock);
if (!pipi)
break;
while ((pipi = smtc_ipi_dq(&IPIQ[smp_processor_id()]))) {
self_ipi(pipi);
smtc_cpu_stats[smp_processor_id()].selfipis++;
smtc_cpu_stats[cpu].selfipis++;
}
}
}
void smtc_ipi_replay(void)
{
raw_local_irq_disable();
__smtc_ipi_replay();
}
EXPORT_SYMBOL(smtc_ipi_replay);
void smtc_idle_loop_hook(void)
@@ -1132,7 +1152,13 @@ void smtc_idle_loop_hook(void)
* is in use, there should never be any.
*/
#ifndef CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY
smtc_ipi_replay();
{
unsigned long flags;
local_irq_save(flags);
__smtc_ipi_replay();
local_irq_restore(flags);
}
#endif /* CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY */
}