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Subject[PATCH] ACPI: Avoid calling request_irq() many times for the same interrupt
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

In principle acpi_os_install_interrupt_handler() may be called
multiple times for different interrupts, either from
acpi_ev_get_gpe_xrupt_block(), or from acpi_ev_install_sci_handler().
However, it always attempts to request the same interrupt,
acpi_gbl_FADT.sci_interrupt and it doesn't check whether or not this
interrupt has already been requested.

Modify this function so that it refuses to request interrupts other
than acpi_gbl_FADT.sci_interrupt and change
acpi_os_remove_interrupt_handler() so that it refuses to free such
interrupts. Use the observation that the only supported ACPI
interrupt must be equal to acpi_gbl_FADT.sci_interrupt and drop an
unnecessary variable acpi_irq_irq.

This change has been tested on Toshiba Portege R500 and HP nx6325
without introducing any visible problems.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/acpi/osl.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

Index: linux-2.6/drivers/acpi/osl.c
===================================================================
--- linux-2.6.orig/drivers/acpi/osl.c
+++ linux-2.6/drivers/acpi/osl.c
@@ -76,7 +76,6 @@ EXPORT_SYMBOL(acpi_in_debugger);
extern char line_buf[80];
#endif /*ENABLE_DEBUGGER */

-static unsigned int acpi_irq_irq;
static acpi_osd_handler acpi_irq_handler;
static void *acpi_irq_context;
static struct workqueue_struct *kacpid_wq;
@@ -532,11 +531,15 @@ acpi_os_install_interrupt_handler(u32 gs
acpi_irq_stats_init();

/*
- * Ignore the GSI from the core, and use the value in our copy of the
- * FADT. It may not be the same if an interrupt source override exists
- * for the SCI.
+ * ACPI interrupts different from the SCI in our copy of the FADT are
+ * not supported.
*/
- gsi = acpi_gbl_FADT.sci_interrupt;
+ if (gsi != acpi_gbl_FADT.sci_interrupt)
+ return AE_BAD_PARAMETER;
+
+ if (acpi_irq_handler)
+ return AE_ALREADY_ACQUIRED;
+
if (acpi_gsi_to_irq(gsi, &irq) < 0) {
printk(KERN_ERR PREFIX "SCI (ACPI GSI %d) not registered\n",
gsi);
@@ -547,20 +550,20 @@ acpi_os_install_interrupt_handler(u32 gs
acpi_irq_context = context;
if (request_irq(irq, acpi_irq, IRQF_SHARED, "acpi", acpi_irq)) {
printk(KERN_ERR PREFIX "SCI (IRQ%d) allocation failed\n", irq);
+ acpi_irq_handler = NULL;
return AE_NOT_ACQUIRED;
}
- acpi_irq_irq = irq;

return AE_OK;
}

acpi_status acpi_os_remove_interrupt_handler(u32 irq, acpi_osd_handler handler)
{
- if (irq) {
- free_irq(irq, acpi_irq);
- acpi_irq_handler = NULL;
- acpi_irq_irq = 0;
- }
+ if (irq != acpi_gbl_FADT.sci_interrupt)
+ return AE_BAD_PARAMETER;
+
+ free_irq(irq, acpi_irq);
+ acpi_irq_handler = NULL;

return AE_OK;
}
@@ -1619,7 +1622,7 @@ acpi_status __init acpi_os_initialize1(v
acpi_status acpi_os_terminate(void)
{
if (acpi_irq_handler) {
- acpi_os_remove_interrupt_handler(acpi_irq_irq,
+ acpi_os_remove_interrupt_handler(acpi_gbl_FADT.sci_interrupt,
acpi_irq_handler);
}


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