linux-kernel - [16/26] x86, mrst: use a temporary variable for SFI irq

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Date:	Fri, 18 Nov 2011 15:58:29 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [16/26] x86, mrst: use a temporary variable for SFI irq

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mika Westerberg <mika.westerberg@...ux.intel.com>

commit 153b19a3b9fd8b9478495b9ee1f93f6a77c564f9 upstream.

SFI tables reside in RAM and should not be modified once they are
written.  Current code went to set pentry->irq to zero which causes
subsequent reads to fail with invalid SFI table checksum.  This will
break kexec as the second kernel fails to validate SFI tables.

To fix this we use temporary variable for irq number.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/platform/mrst/mrst.c |   22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

--- a/arch/x86/platform/mrst/mrst.c
+++ b/arch/x86/platform/mrst/mrst.c
@@ -678,38 +678,40 @@ static int __init sfi_parse_devs(struct
 	pentry = (struct sfi_device_table_entry *)sb->pentry;
 
 	for (i = 0; i < num; i++, pentry++) {
-		if (pentry->irq != (u8)0xff) { /* native RTE case */
+		int irq = pentry->irq;
+
+		if (irq != (u8)0xff) { /* native RTE case */
 			/* these SPI2 devices are not exposed to system as PCI
 			 * devices, but they have separate RTE entry in IOAPIC
 			 * so we have to enable them one by one here
 			 */
-			ioapic = mp_find_ioapic(pentry->irq);
+			ioapic = mp_find_ioapic(irq);
 			irq_attr.ioapic = ioapic;
-			irq_attr.ioapic_pin = pentry->irq;
+			irq_attr.ioapic_pin = irq;
 			irq_attr.trigger = 1;
 			irq_attr.polarity = 1;
-			io_apic_set_pci_routing(NULL, pentry->irq, &irq_attr);
+			io_apic_set_pci_routing(NULL, irq, &irq_attr);
 		} else
-			pentry->irq = 0; /* No irq */
+			irq = 0; /* No irq */
 
 		switch (pentry->type) {
 		case SFI_DEV_TYPE_IPC:
 			/* ID as IRQ is a hack that will go away */
-			pdev = platform_device_alloc(pentry->name, pentry->irq);
+			pdev = platform_device_alloc(pentry->name, irq);
 			if (pdev == NULL) {
 				pr_err("out of memory for SFI platform device '%s'.\n",
 							pentry->name);
 				continue;
 			}
-			install_irq_resource(pdev, pentry->irq);
+			install_irq_resource(pdev, irq);
 			pr_debug("info[%2d]: IPC bus, name = %16.16s, "
-				"irq = 0x%2x\n", i, pentry->name, pentry->irq);
+				"irq = 0x%2x\n", i, pentry->name, irq);
 			sfi_handle_ipc_dev(pdev);
 			break;
 		case SFI_DEV_TYPE_SPI:
 			memset(&spi_info, 0, sizeof(spi_info));
 			strncpy(spi_info.modalias, pentry->name, SFI_NAME_LEN);
-			spi_info.irq = pentry->irq;
+			spi_info.irq = irq;
 			spi_info.bus_num = pentry->host_num;
 			spi_info.chip_select = pentry->addr;
 			spi_info.max_speed_hz = pentry->max_freq;
@@ -726,7 +728,7 @@ static int __init sfi_parse_devs(struct
 			memset(&i2c_info, 0, sizeof(i2c_info));
 			bus = pentry->host_num;
 			strncpy(i2c_info.type, pentry->name, SFI_NAME_LEN);
-			i2c_info.irq = pentry->irq;
+			i2c_info.irq = irq;
 			i2c_info.addr = pentry->addr;
 			pr_debug("info[%2d]: I2C bus = %d, name = %16.16s, "
 				"irq = 0x%2x, addr = 0x%x\n", i, bus,


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