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Subject[patch 20/60] iucv: Locking free version of iucv_message_(receive|send)
From: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>

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>
---
include/net/iucv/iucv.h | 45 ++++++++++++++
net/iucv/iucv.c | 152 ++++++++++++++++++++++++++++++++++++------------
2 files changed, 161 insertions(+), 36 deletions(-)
Index: quilt-2.6/include/net/iucv/iucv.h
===================================================================
--- quilt-2.6.orig/include/net/iucv/iucv.h
+++ quilt-2.6/include/net/iucv/iucv.h
@@ -337,12 +337,35 @@ int iucv_message_purge(struct iucv_path
* 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);

/**
+ * __iucv_message_receive
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: flags that affect 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: 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);
+
+/**
* iucv_message_reject
* @path: address of iucv path structure
* @msg: address of iucv msg structure
@@ -386,12 +409,34 @@ int iucv_message_reply(struct iucv_path
* 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);

/**
+ * __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 data 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: no locking.
+ *
+ * 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);
+
+/**
* iucv_message_send2way
* @path: address of iucv path structure
* @msg: address of iucv msg structure
Index: quilt-2.6/net/iucv/iucv.c
===================================================================
--- quilt-2.6.orig/net/iucv/iucv.c
+++ quilt-2.6/net/iucv/iucv.c
@@ -957,7 +957,52 @@ int iucv_message_purge(struct iucv_path
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_pat
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
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 *
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;
}
--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.



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