[S390] iucv: Locking free version of iucv_message_(receive|send)

Provide a locking free version of iucv_message_receive and iucv_message_send
that do not call local_bh_enable in a spin_lock_(bh|irqsave)() context.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>

1 files changed, 116 insertions, 36 deletions

diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index d7b54b5bfa69..6bf51f7e597f 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -957,7 +957,52 @@ int iucv_message_purge(struct iucv_path *path, struct iucv_message *msg,
 EXPORT_SYMBOL(iucv_message_purge);
 
 /**
- * iucv_message_receive
+ * iucv_message_receive_iprmdata
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is received (IUCV_IPBUFLST)
+ * @buffer: address of data buffer or address of struct iucv_array
+ * @size: length of data buffer
+ * @residual:
+ *
+ * Internal function used by iucv_message_receive and __iucv_message_receive
+ * to receive RMDATA data stored in struct iucv_message.
+ */
+static int iucv_message_receive_iprmdata(struct iucv_path *path,
+                                         struct iucv_message *msg,
+                                         u8 flags, void *buffer,
+                                         size_t size, size_t *residual)
+{
+        struct iucv_array *array;
+        u8 *rmmsg;
+        size_t copy;
+
+        /*
+         * Message is 8 bytes long and has been stored to the
+         * message descriptor itself.
+         */
+        if (residual)
+                *residual = abs(size - 8);
+        rmmsg = msg->rmmsg;
+        if (flags & IUCV_IPBUFLST) {
+                /* Copy to struct iucv_array. */
+                size = (size < 8) ? size : 8;
+                for (array = buffer; size > 0; array++) {
+                        copy = min_t(size_t, size, array->length);
+                        memcpy((u8 *)(addr_t) array->address,
+                                rmmsg, copy);
+                        rmmsg += copy;
+                        size -= copy;
+                }
+        } else {
+                /* Copy to direct buffer. */
+                memcpy(buffer, rmmsg, min_t(size_t, size, 8));
+        }
+        return 0;
+}
+
+/**
+ * __iucv_message_receive
  * @path: address of iucv path structure
  * @msg: address of iucv msg structure
  * @flags: how the message is received (IUCV_IPBUFLST)
@@ -969,44 +1014,19 @@ EXPORT_SYMBOL(iucv_message_purge);
  * established paths. This function will deal with RMDATA messages
  * embedded in struct iucv_message as well.
  *
+ * Locking:     no locking
+ *
  * Returns the result from the CP IUCV call.
  */
-int iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
-                         u8 flags, void *buffer, size_t size, size_t *residual)
+int __iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
+                           u8 flags, void *buffer, size_t size, size_t *residual)
 {
         union iucv_param *parm;
-        struct iucv_array *array;
-        u8 *rmmsg;
-        size_t copy;
         int rc;
 
-        if (msg->flags & IUCV_IPRMDATA) {
-                /*
-                 * Message is 8 bytes long and has been stored to the
-                 * message descriptor itself.
-                 */
-                rc = (size < 8) ? 5 : 0;
-                if (residual)
-                        *residual = abs(size - 8);
-                rmmsg = msg->rmmsg;
-                if (flags & IUCV_IPBUFLST) {
-                        /* Copy to struct iucv_array. */
-                        size = (size < 8) ? size : 8;
-                        for (array = buffer; size > 0; array++) {
-                                copy = min_t(size_t, size, array->length);
-                                memcpy((u8 *)(addr_t) array->address,
-                                       rmmsg, copy);
-                                rmmsg += copy;
-                                size -= copy;
-                        }
-                } else {
-                        /* Copy to direct buffer. */
-                        memcpy(buffer, rmmsg, min_t(size_t, size, 8));
-                }
-                return 0;
-        }
-
-        local_bh_disable();
+        if (msg->flags & IUCV_IPRMDATA)
+                return iucv_message_receive_iprmdata(path, msg, flags,
+                                                     buffer, size, residual);
         parm = iucv_param[smp_processor_id()];
         memset(parm, 0, sizeof(union iucv_param));
         parm->db.ipbfadr1 = (u32)(addr_t) buffer;
@@ -1022,6 +1042,37 @@ int iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
                 if (residual)
                         *residual = parm->db.ipbfln1f;
         }
+        return rc;
+}
+EXPORT_SYMBOL(__iucv_message_receive);
+
+/**
+ * iucv_message_receive
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is received (IUCV_IPBUFLST)
+ * @buffer: address of data buffer or address of struct iucv_array
+ * @size: length of data buffer
+ * @residual:
+ *
+ * This function receives messages that are being sent to you over
+ * established paths. This function will deal with RMDATA messages
+ * embedded in struct iucv_message as well.
+ *
+ * Locking:     local_bh_enable/local_bh_disable
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
+                         u8 flags, void *buffer, size_t size, size_t *residual)
+{
+        int rc;
+
+        if (msg->flags & IUCV_IPRMDATA)
+                return iucv_message_receive_iprmdata(path, msg, flags,
+                                                     buffer, size, residual);
+        local_bh_disable();
+        rc = __iucv_message_receive(path, msg, flags, buffer, size, residual);
         local_bh_enable();
         return rc;
 }
@@ -1101,7 +1152,7 @@ int iucv_message_reply(struct iucv_path *path, struct iucv_message *msg,
 EXPORT_SYMBOL(iucv_message_reply);
 
 /**
- * iucv_message_send
+ * __iucv_message_send
  * @path: address of iucv path structure
  * @msg: address of iucv msg structure
  * @flags: how the message is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
@@ -1113,15 +1164,16 @@ EXPORT_SYMBOL(iucv_message_reply);
  * transmitted is in a buffer and this is a one-way message and the
  * receiver will not reply to the message.
  *
+ * Locking:     no locking
+ *
  * Returns the result from the CP IUCV call.
  */
-int iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
+int __iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
                       u8 flags, u32 srccls, void *buffer, size_t size)
 {
         union iucv_param *parm;
         int rc;
 
-        local_bh_disable();
         parm = iucv_param[smp_processor_id()];
         memset(parm, 0, sizeof(union iucv_param));
         if (flags & IUCV_IPRMDATA) {
@@ -1144,6 +1196,34 @@ int iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
         rc = iucv_call_b2f0(IUCV_SEND, parm);
         if (!rc)
                 msg->id = parm->db.ipmsgid;
+        return rc;
+}
+EXPORT_SYMBOL(__iucv_message_send);
+
+/**
+ * iucv_message_send
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
+ * @srccls: source class of message
+ * @buffer: address of send buffer or address of struct iucv_array
+ * @size: length of send buffer
+ *
+ * This function transmits data to another application. Data to be
+ * transmitted is in a buffer and this is a one-way message and the
+ * receiver will not reply to the message.
+ *
+ * Locking:     local_bh_enable/local_bh_disable
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
+                      u8 flags, u32 srccls, void *buffer, size_t size)
+{
+        int rc;
+
+        local_bh_disable();
+        rc = __iucv_message_send(path, msg, flags, srccls, buffer, size);
         local_bh_enable();
         return rc;
 }