linux-kernel - [PATCH 5/5] platform/x86: think-lmi: mutex protection around multiple WMI calls

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Message-Id: <20230525193132.3727-5-mpearson-lenovo@squebb.ca>
Date:   Thu, 25 May 2023 15:31:32 -0400
From:   Mark Pearson <mpearson-lenovo@...ebb.ca>
To:     mpearson-lenovo@...ebb.ca
Cc:     hdegoede@...hat.com, markgross@...nel.org,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] platform/x86: think-lmi: mutex protection around multiple WMI calls

Add mutex protection around cases where an operation needs multiple
WMI calls - e.g. setting password.

Signed-off-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
---
Changes in V2: New commit added after review of other patches in series.

 drivers/platform/x86/think-lmi.c | 46 ++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 11 deletions(-)

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 64cd453d6e7d..f3e1e4dacba2 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -14,6 +14,7 @@
 #include <linux/acpi.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
+#include <linux/mutex.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/dmi.h>
@@ -195,6 +196,7 @@ static const char * const level_options[] = {
 };
 static struct think_lmi tlmi_priv;
 static struct class *fw_attr_class;
+static DEFINE_MUTEX(tlmi_mutex);
 
 /* ------ Utility functions ------------*/
 /* Strip out CR if one is present */
@@ -463,23 +465,32 @@ static ssize_t new_password_store(struct kobject *kobj,
 			sprintf(pwd_type, "%s", setting->pwd_type);
 		}
 
+		mutex_lock(&tlmi_mutex);
 		ret = tlmi_opcode_setting("WmiOpcodePasswordType", pwd_type);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
-
+		}
 		if (tlmi_priv.pwd_admin->valid) {
 			ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
 					tlmi_priv.pwd_admin->password);
-			if (ret)
+			if (ret) {
+				mutex_unlock(&tlmi_mutex);
 				goto out;
+			}
 		}
 		ret = tlmi_opcode_setting("WmiOpcodePasswordCurrent01", setting->password);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
+		}
 		ret = tlmi_opcode_setting("WmiOpcodePasswordNew01", new_pwd);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
+		}
 		ret = tlmi_simple_call(LENOVO_OPCODE_IF_GUID, "WmiOpcodePasswordSetUpdate;");
+		mutex_unlock(&tlmi_mutex);
 	} else {
 		/* Format: 'PasswordType,CurrentPw,NewPw,Encoding,KbdLang;' */
 		auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s,%s,%s;",
@@ -1000,11 +1011,16 @@ static ssize_t current_value_store(struct kobject *kobj,
 			goto out;
 		}
 
+		mutex_lock(&tlmi_mutex);
 		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTING_CERT_GUID, set_str);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
+		}
 		ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
 				tlmi_priv.pwd_admin->save_signature);
+
+		mutex_unlock(&tlmi_mutex);
 		if (ret)
 			goto out;
 	} else if (tlmi_priv.opcode_support) {
@@ -1021,18 +1037,23 @@ static ssize_t current_value_store(struct kobject *kobj,
 			goto out;
 		}
 
+		mutex_lock(&tlmi_mutex);
 		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
+		}
 
 		if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
 			ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
 					tlmi_priv.pwd_admin->password);
-			if (ret)
+			if (ret) {
+				mutex_unlock(&tlmi_mutex);
 				goto out;
+			}
 		}
-
 		ret = tlmi_save_bios_settings("");
+		mutex_unlock(&tlmi_mutex);
 	} else { /* old non opcode based authentication method (deprecated)*/
 		if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
 			auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
@@ -1056,14 +1077,17 @@ static ssize_t current_value_store(struct kobject *kobj,
 			goto out;
 		}
 
+		mutex_lock(&tlmi_mutex);
 		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&tlmi_mutex);
 			goto out;
-
+		}
 		if (auth_str)
 			ret = tlmi_save_bios_settings(auth_str);
 		else
 			ret = tlmi_save_bios_settings("");
+		mutex_unlock(&tlmi_mutex);
 	}
 	if (!ret && !tlmi_priv.pending_changes) {
 		tlmi_priv.pending_changes = true;
-- 
2.40.1