1 files changed, 11 insertions, 7 deletions

diff --git a/arch/s390/kernel/cpcmd.c b/arch/s390/kernel/cpcmd.c
index 1eae74e72f95..a5972f1541fe 100644
--- a/arch/s390/kernel/cpcmd.c
+++ b/arch/s390/kernel/cpcmd.c
@@ -21,14 +21,15 @@ static DEFINE_SPINLOCK(cpcmd_lock);
 static char cpcmd_buf[241];
 
 /*
- * the caller of __cpcmd has to ensure that the response buffer is below 2 GB
+ * __cpcmd has some restrictions over cpcmd
+ *  - the response buffer must reside below 2GB (if any)
+ *  - __cpcmd is unlocked and therefore not SMP-safe
  */
 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
 {
-        unsigned long flags, cmdlen;
+        unsigned cmdlen;
         int return_code, return_len;
 
-        spin_lock_irqsave(&cpcmd_lock, flags);
         cmdlen = strlen(cmd);
         BUG_ON(cmdlen > 240);
         memcpy(cpcmd_buf, cmd, cmdlen);
@@ -74,7 +75,6 @@ int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
                         : "+d" (reg3) : "d" (reg2) : "cc");
                 return_code = (int) reg3;
         }
-        spin_unlock_irqrestore(&cpcmd_lock, flags);
         if (response_code != NULL)
                 *response_code = return_code;
         return return_len;
@@ -82,15 +82,18 @@ int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
 
 EXPORT_SYMBOL(__cpcmd);
 
-#ifdef CONFIG_64BIT
 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
 {
         char *lowbuf;
         int len;
+        unsigned long flags;
 
         if ((rlen == 0) || (response == NULL)
-            || !((unsigned long)response >> 31))
+            || !((unsigned long)response >> 31)) {
+                spin_lock_irqsave(&cpcmd_lock, flags);
                 len = __cpcmd(cmd, response, rlen, response_code);
+                spin_unlock_irqrestore(&cpcmd_lock, flags);
+        }
         else {
                 lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
                 if (!lowbuf) {
@@ -98,7 +101,9 @@ int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
                                 "cpcmd: could not allocate response buffer\n");
                         return -ENOMEM;
                 }
+                spin_lock_irqsave(&cpcmd_lock, flags);
                 len = __cpcmd(cmd, lowbuf, rlen, response_code);
+                spin_unlock_irqrestore(&cpcmd_lock, flags);
                 memcpy(response, lowbuf, rlen);
                 kfree(lowbuf);
         }
@@ -106,4 +111,3 @@ int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
 }
 
 EXPORT_SYMBOL(cpcmd);
-#endif          /* CONFIG_64BIT */