Merge tag 'keys-fixes-20160412' of git://git.kernel.org/pub/scm/linux/kernel/git...

[deliverable/linux.git] / drivers / firmware / qemu_fw_cfg.c

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index fedbff55a7f3848872b7d0196086bc0f56caa0c7..815c4a5cae543e228a634eae28241bc6f24ac1ed 100644 (file)
--- 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 */
@@ -727,12 +743,18 @@ 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)