[S390] cpcmd <-> __cpcmd calling issues

In case of reipl cpcmd gets called when all other cpus are not running
anymore. To prevent deadlocks change __cpcmd so that it doesn't take
any locks and call cpcmd or __cpcmd, whatever is correct in the current
context.

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

3 files changed, 21 insertions, 17 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 */
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 77f4aff630fe..101b003cfabf 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -677,7 +677,7 @@ void do_reipl(void)
                 else
                         sprintf(buf, "IPL %X LOADPARM '%s'",
                                 reipl_block_ccw->ipl_info.ccw.devno, loadparm);
-                cpcmd(buf, NULL, 0, NULL);
+                __cpcmd(buf, NULL, 0, NULL);
                 break;
         case IPL_METHOD_CCW_DIAG:
                 diag308(DIAG308_SET, reipl_block_ccw);
@@ -691,12 +691,12 @@ void do_reipl(void)
                 diag308(DIAG308_IPL, NULL);
                 break;
         case IPL_METHOD_FCP_RO_VM:
-                cpcmd("IPL", NULL, 0, NULL);
+                __cpcmd("IPL", NULL, 0, NULL);
                 break;
         case IPL_METHOD_NONE:
         default:
                 if (MACHINE_IS_VM)
-                        cpcmd("IPL", NULL, 0, NULL);
+                        __cpcmd("IPL", NULL, 0, NULL);
                 diag308(DIAG308_IPL, NULL);
                 break;
         }
@@ -732,9 +732,9 @@ static void do_dump(void)
         case IPL_METHOD_CCW_VM:
                 dump_smp_stop_all();
                 sprintf(buf, "STORE STATUS");
-                cpcmd(buf, NULL, 0, NULL);
+                __cpcmd(buf, NULL, 0, NULL);
                 sprintf(buf, "IPL %X", dump_block_ccw->ipl_info.ccw.devno);
-                cpcmd(buf, NULL, 0, NULL);
+                __cpcmd(buf, NULL, 0, NULL);
                 break;
         case IPL_METHOD_CCW_DIAG:
                 diag308(DIAG308_SET, dump_block_ccw);
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 2aa13e8e000a..9bbef0c65584 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -229,11 +229,11 @@ static void __init conmode_default(void)
         char *ptr;
 
         if (MACHINE_IS_VM) {
-                __cpcmd("QUERY CONSOLE", query_buffer, 1024, NULL);
+                cpcmd("QUERY CONSOLE", query_buffer, 1024, NULL);
                 console_devno = simple_strtoul(query_buffer + 5, NULL, 16);
                 ptr = strstr(query_buffer, "SUBCHANNEL =");
                 console_irq = simple_strtoul(ptr + 13, NULL, 16);
-                __cpcmd("QUERY TERM", query_buffer, 1024, NULL);
+                cpcmd("QUERY TERM", query_buffer, 1024, NULL);
                 ptr = strstr(query_buffer, "CONMODE");
                 /*
                  * Set the conmode to 3215 so that the device recognition 
@@ -242,7 +242,7 @@ static void __init conmode_default(void)
                  * 3215 and the 3270 driver will try to access the console
                  * device (3215 as console and 3270 as normal tty).
                  */
-                __cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
+                cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
                 if (ptr == NULL) {
 #if defined(CONFIG_SCLP_CONSOLE)
                         SET_CONSOLE_SCLP;
@@ -299,14 +299,14 @@ static void do_machine_restart_nonsmp(char * __unused)
 static void do_machine_halt_nonsmp(void)
 {
         if (MACHINE_IS_VM && strlen(vmhalt_cmd) > 0)
-                cpcmd(vmhalt_cmd, NULL, 0, NULL);
+                __cpcmd(vmhalt_cmd, NULL, 0, NULL);
         signal_processor(smp_processor_id(), sigp_stop_and_store_status);
 }
 
 static void do_machine_power_off_nonsmp(void)
 {
         if (MACHINE_IS_VM && strlen(vmpoff_cmd) > 0)
-                cpcmd(vmpoff_cmd, NULL, 0, NULL);
+                __cpcmd(vmpoff_cmd, NULL, 0, NULL);
         signal_processor(smp_processor_id(), sigp_stop_and_store_status);
 }