[S390] cio: Use locks when accessing /sys/firmware/cpi data.

Mutex locks are used to avoid problems when /sys/firmware/cpi data
are accessed to in parallel.

Signed-off-by: Michael Ernst <mernst@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 39 insertions, 6 deletions

diff --git a/drivers/s390/char/sclp_cpi_sys.c b/drivers/s390/char/sclp_cpi_sys.c
index 9f37456222e9..005f330ed926 100644
--- a/drivers/s390/char/sclp_cpi_sys.c
+++ b/drivers/s390/char/sclp_cpi_sys.c
@@ -27,6 +27,8 @@
 #define CPI_LENGTH_NAME 8
 #define CPI_LENGTH_LEVEL 16
 
+static DEFINE_MUTEX(sclp_cpi_mutex);
+
 struct cpi_evbuf {
         struct evbuf_header header;
         u8      id_format;
@@ -223,7 +225,12 @@ static void set_string(char *attr, const char *value)
 static ssize_t system_name_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *page)
 {
-        return snprintf(page, PAGE_SIZE, "%s\n", system_name);
+        int rc;
+
+        mutex_lock(&sclp_cpi_mutex);
+        rc = snprintf(page, PAGE_SIZE, "%s\n", system_name);
+        mutex_unlock(&sclp_cpi_mutex);
+        return rc;
 }
 
 static ssize_t system_name_store(struct kobject *kobj,
@@ -237,7 +244,9 @@ static ssize_t system_name_store(struct kobject *kobj,
         if (rc)
                 return rc;
 
+        mutex_lock(&sclp_cpi_mutex);
         set_string(system_name, buf);
+        mutex_unlock(&sclp_cpi_mutex);
 
         return len;
 }
@@ -248,7 +257,12 @@ static struct kobj_attribute system_name_attr =
 static ssize_t sysplex_name_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *page)
 {
-        return snprintf(page, PAGE_SIZE, "%s\n", sysplex_name);
+        int rc;
+
+        mutex_lock(&sclp_cpi_mutex);
+        rc = snprintf(page, PAGE_SIZE, "%s\n", sysplex_name);
+        mutex_unlock(&sclp_cpi_mutex);
+        return rc;
 }
 
 static ssize_t sysplex_name_store(struct kobject *kobj,
@@ -262,7 +276,9 @@ static ssize_t sysplex_name_store(struct kobject *kobj,
         if (rc)
                 return rc;
 
+        mutex_lock(&sclp_cpi_mutex);
         set_string(sysplex_name, buf);
+        mutex_unlock(&sclp_cpi_mutex);
 
         return len;
 }
@@ -273,7 +289,12 @@ static struct kobj_attribute sysplex_name_attr =
 static ssize_t system_type_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *page)
 {
-        return snprintf(page, PAGE_SIZE, "%s\n", system_type);
+        int rc;
+
+        mutex_lock(&sclp_cpi_mutex);
+        rc = snprintf(page, PAGE_SIZE, "%s\n", system_type);
+        mutex_unlock(&sclp_cpi_mutex);
+        return rc;
 }
 
 static ssize_t system_type_store(struct kobject *kobj,
@@ -287,7 +308,9 @@ static ssize_t system_type_store(struct kobject *kobj,
         if (rc)
                 return rc;
 
+        mutex_lock(&sclp_cpi_mutex);
         set_string(system_type, buf);
+        mutex_unlock(&sclp_cpi_mutex);
 
         return len;
 }
@@ -298,8 +321,11 @@ static struct kobj_attribute system_type_attr =
 static ssize_t system_level_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *page)
 {
-        unsigned long long level = system_level;
+        unsigned long long level;
 
+        mutex_lock(&sclp_cpi_mutex);
+        level = system_level;
+        mutex_unlock(&sclp_cpi_mutex);
         return snprintf(page, PAGE_SIZE, "%#018llx\n", level);
 }
 
@@ -320,8 +346,9 @@ static ssize_t system_level_store(struct kobject *kobj,
         if (*endp)
                 return -EINVAL;
 
+        mutex_lock(&sclp_cpi_mutex);
         system_level = level;
-
+        mutex_unlock(&sclp_cpi_mutex);
         return len;
 }
 
@@ -334,7 +361,9 @@ static ssize_t set_store(struct kobject *kobj,
 {
         int rc;
 
+        mutex_lock(&sclp_cpi_mutex);
         rc = cpi_req();
+        mutex_unlock(&sclp_cpi_mutex);
         if (rc)
                 return rc;
 
@@ -373,12 +402,16 @@ int sclp_cpi_set_data(const char *system, const char *sysplex, const char *type,
         if (rc)
                 return rc;
 
+        mutex_lock(&sclp_cpi_mutex);
         set_string(system_name, system);
         set_string(sysplex_name, sysplex);
         set_string(system_type, type);
         system_level = level;
 
-        return cpi_req();
+        rc = cpi_req();
+        mutex_unlock(&sclp_cpi_mutex);
+
+        return rc;
 }
 EXPORT_SYMBOL(sclp_cpi_set_data);