Merge 4.6-rc4 into driver-core-next

We want those fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 1 deletions

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 7bba76c0206c..d999fe3b1de6 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -77,12 +77,28 @@ static inline u16 fw_cfg_sel_endianness(u16 key)
 static inline void fw_cfg_read_blob(u16 key,
 				    void *buf, loff_t pos, size_t count)
 {
+	u32 glk;
+	acpi_status status;
+
+	/* If we have ACPI, ensure mutual exclusion against any potential
+	 * device access by the firmware, e.g. via AML methods:
+	 */
+	status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
+	if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
+		/* Should never get here */
+		WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
+		memset(buf, 0, count);
+		return;
+	}
+
 	mutex_lock(&fw_cfg_dev_lock);
 	iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
 	while (pos-- > 0)
 		ioread8(fw_cfg_reg_data);
 	ioread8_rep(fw_cfg_reg_data, buf, count);
 	mutex_unlock(&fw_cfg_dev_lock);
+
+	acpi_release_global_lock(glk);
 }
 
 /* clean up fw_cfg device i/o */
@@ -725,12 +741,18 @@ device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 
 static int __init fw_cfg_sysfs_init(void)
 {
+	int ret;
+
 	/* create /sys/firmware/qemu_fw_cfg/ top level directory */
 	fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
 	if (!fw_cfg_top_ko)
 		return -ENOMEM;
 
-	return platform_driver_register(&fw_cfg_sysfs_driver);
+	ret = platform_driver_register(&fw_cfg_sysfs_driver);
+	if (ret)
+		fw_cfg_kobj_cleanup(fw_cfg_top_ko);
+
+	return ret;
 }
 
 static void __exit fw_cfg_sysfs_exit(void)