Patchwork [3.11,161/208] PCI: Disable Bus Master only on kexec reboot

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Submitter Luis Henriques
Date Dec. 19, 2013, 11:54 a.m.
Message ID <>
Download mbox | patch
Permalink /patch/303467/
State New
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Luis Henriques - Dec. 19, 2013, 11:54 a.m. -stable review patch.  If anyone has any objections, please let me know.


From: Khalid Aziz <>

commit 4fc9bbf98fd66f879e628d8537ba7c240be2b58e upstream.

Add a flag to tell the PCI subsystem that kernel is shutting down in
preparation to kexec a kernel.  Add code in PCI subsystem to use this flag
to clear Bus Master bit on PCI devices only in case of kexec reboot.

This fixes a power-off problem on Acer Aspire V5-573G and likely other
machines and avoids any other issues caused by clearing Bus Master bit on
PCI devices in normal shutdown path.  The problem was introduced by
b566a22c2332 ("PCI: disable Bus Master on PCI device shutdown").

This patch is based on discussion at

Reported-by: Chang Liu <>
Signed-off-by: Khalid Aziz <>
Signed-off-by: Bjorn Helgaas <>
Acked-by: Konstantin Khlebnikov <>
Signed-off-by: Luis Henriques <>
 drivers/pci/pci-driver.c | 12 +++++++++---
 include/linux/kexec.h    |  3 +++
 kernel/kexec.c           |  4 ++++
 3 files changed, 16 insertions(+), 3 deletions(-)


diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index e6515e2..6f9b44b 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -19,6 +19,7 @@ 
 #include <linux/cpu.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
+#include <linux/kexec.h>
 #include "pci.h"
 struct pci_dynid {
@@ -388,12 +389,17 @@  static void pci_device_shutdown(struct device *dev)
-	 * Turn off Bus Master bit on the device to tell it to not
-	 * continue to do DMA. Don't touch devices in D3cold or unknown states.
+	 * If this is a kexec reboot, turn off Bus Master bit on the
+	 * device to tell it to not continue to do DMA. Don't touch
+	 * devices in D3cold or unknown states.
+	 * If it is not a kexec reboot, firmware will hit the PCI
+	 * devices with big hammer and stop their DMA any way.
-	if (pci_dev->current_state <= PCI_D3hot)
+	if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot))
 #ifdef CONFIG_PM
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index d78d28a..5fd33dc 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -198,6 +198,9 @@  extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
 extern size_t vmcoreinfo_size;
 extern size_t vmcoreinfo_max_size;
+/* flag to track if kexec reboot is in progress */
+extern bool kexec_in_progress;
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 59f7b55..1f8d938 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -47,6 +47,9 @@  u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
 size_t vmcoreinfo_size;
 size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
+/* Flag to indicate we are going to kexec a new kernel */
+bool kexec_in_progress = false;
 /* Location of the reserved area for the crash kernel */
 struct resource crashk_res = {
 	.name  = "Crash kernel",
@@ -1678,6 +1681,7 @@  int kernel_kexec(void)
 	} else
+		kexec_in_progress = true;
 		printk(KERN_EMERG "Starting new kernel\n");