staging: lustre: kg_sem semaphore handling is incorrectly

During the removal of the cfs wrappers the kg_sem semaphore
was handled incorrectly. We need to take a write lock when
writing data to the kkuc_groups. The libcfs_kkuc_group_foreach
needs to only take a read lock. This makes use match the
OpenSFS development branch.

Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
index d8230ae..1a052ac 100644 (file)
--- a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
+++ b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
@@ -186,7 +186,7 @@ int libcfs_kkuc_group_put(int group, void *payload)
        int              rc = 0;
        int one_success = 0;
 
-       down_read(&kg_sem);
+       down_write(&kg_sem);
        list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
                if (reg->kr_fp != NULL) {
                        rc = libcfs_kkuc_msg_put(reg->kr_fp, payload);
@@ -198,7 +198,7 @@ int libcfs_kkuc_group_put(int group, void *payload)
                        }
                }
        }
-       up_read(&kg_sem);
+       up_write(&kg_sem);
 
        /* don't return an error if the message has been delivered
         * at least to one agent */
@@ -230,12 +230,12 @@ int libcfs_kkuc_group_foreach(int group, libcfs_kkuc_cb_t cb_func,
        if (kkuc_groups[group].next == NULL)
                return 0;
 
-       down_write(&kg_sem);
+       down_read(&kg_sem);
        list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
                if (reg->kr_fp != NULL)
                        rc = cb_func(reg->kr_data, cb_arg);
        }
-       up_write(&kg_sem);
+       up_read(&kg_sem);
 
        return rc;
 }