[S390] cio: fix parallel cm_enable processing.

It is now possible to trigger cm_enable processing several times in
parallel without causing a kernel panic.

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, 0 insertions, 3 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index b6a40c20780d..5de86908b0d0 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -766,7 +766,6 @@ chsc_secm(struct channel_subsystem *css, int enable)
         if (!secm_area)
                 return -ENOMEM;
 
-        mutex_lock(&css->mutex);
         if (enable && !css->cm_enabled) {
                 css->cub_addr1 = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
                 css->cub_addr2 = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
@@ -774,7 +773,6 @@ chsc_secm(struct channel_subsystem *css, int enable)
                         free_page((unsigned long)css->cub_addr1);
                         free_page((unsigned long)css->cub_addr2);
                         free_page((unsigned long)secm_area);
-                        mutex_unlock(&css->mutex);
                         return -ENOMEM;
                 }
         }
@@ -795,7 +793,6 @@ chsc_secm(struct channel_subsystem *css, int enable)
                 free_page((unsigned long)css->cub_addr1);
                 free_page((unsigned long)css->cub_addr2);
         }
-        mutex_unlock(&css->mutex);
         free_page((unsigned long)secm_area);
         return ret;
 }