1 files changed, 27 insertions, 15 deletions

diff --git a/drivers/s390/char/vmlogrdr.c b/drivers/s390/char/vmlogrdr.c
index e40a1b892866..c837d7419a6a 100644
--- a/drivers/s390/char/vmlogrdr.c
+++ b/drivers/s390/char/vmlogrdr.c
@@ -30,7 +30,6 @@
 #include <linux/kmod.h>
 #include <linux/cdev.h>
 #include <linux/device.h>
-#include <linux/smp_lock.h>
 #include <linux/string.h>
 
 MODULE_AUTHOR
@@ -97,6 +96,7 @@ static const struct file_operations vmlogrdr_fops = {
         .open    = vmlogrdr_open,
         .release = vmlogrdr_release,
         .read    = vmlogrdr_read,
+        .llseek  = no_llseek,
 };
 
 
@@ -214,7 +214,7 @@ static void vmlogrdr_iucv_message_pending(struct iucv_path *path,
 
 static int vmlogrdr_get_recording_class_AB(void)
 {
-        char cp_command[]="QUERY COMMAND RECORDING ";
+        static const char cp_command[] = "QUERY COMMAND RECORDING ";
         char cp_response[80];
         char *tail;
         int len,i;
@@ -248,27 +248,25 @@ static int vmlogrdr_recording(struct vmlogrdr_priv_t * logptr,
         char cp_command[80];
         char cp_response[160];
         char *onoff, *qid_string;
+        int rc;
 
-        memset(cp_command, 0x00, sizeof(cp_command));
-        memset(cp_response, 0x00, sizeof(cp_response));
-
-        onoff = ((action == 1) ? "ON" : "OFF");
+        onoff = ((action == 1) ? "ON" : "OFF");
         qid_string = ((recording_class_AB == 1) ? " QID * " : "");
 
-        /*
+        /*
          * The recording commands needs to be called with option QID
          * for guests that have previlege classes A or B.
          * Purging has to be done as separate step, because recording
          * can't be switched on as long as records are on the queue.
          * Doing both at the same time doesn't work.
          */
-
-        if (purge) {
+        if (purge && (action == 1)) {
+                memset(cp_command, 0x00, sizeof(cp_command));
+                memset(cp_response, 0x00, sizeof(cp_response));
                 snprintf(cp_command, sizeof(cp_command),
                          "RECORDING %s PURGE %s",
                          logptr->recording_name,
                          qid_string);
-
                 cpcmd(cp_command, cp_response, sizeof(cp_response), NULL);
         }
 
@@ -278,19 +276,33 @@ static int vmlogrdr_recording(struct vmlogrdr_priv_t * logptr,
                 logptr->recording_name,
                 onoff,
                 qid_string);
-
         cpcmd(cp_command, cp_response, sizeof(cp_response), NULL);
         /* The recording command will usually answer with 'Command complete'
          * on success, but when the specific service was never connected
          * before then there might be an additional informational message
          * 'HCPCRC8072I Recording entry not found' before the
-         * 'Command complete'. So I use strstr rather then the strncmp.
+         * 'Command complete'. So I use strstr rather then the strncmp.
          */
         if (strstr(cp_response,"Command complete"))
-                return 0;
+                rc = 0;
         else
-                return -EIO;
+                rc = -EIO;
+        /*
+         * If we turn recording off, we have to purge any remaining records
+         * afterwards, as a large number of queued records may impact z/VM
+         * performance.
+         */
+        if (purge && (action == 0)) {
+                memset(cp_command, 0x00, sizeof(cp_command));
+                memset(cp_response, 0x00, sizeof(cp_response));
+                snprintf(cp_command, sizeof(cp_command),
+                         "RECORDING %s PURGE %s",
+                         logptr->recording_name,
+                         qid_string);
+                cpcmd(cp_command, cp_response, sizeof(cp_response), NULL);
+        }
 
+        return rc;
 }
 
 
@@ -637,7 +649,7 @@ static ssize_t vmlogrdr_recording_status_show(struct device_driver *driver,
                                               char *buf)
 {
 
-        char cp_command[] = "QUERY RECORDING ";
+        static const char cp_command[] = "QUERY RECORDING ";
         int len;
 
         cpcmd(cp_command, buf, 4096, NULL);