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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Greybus operations
  *
  * Copyright 2014-2015 Google Inc.
  * Copyright 2014-2015 Linaro Ltd.
  */
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <linux/greybus.h>
 
 #include "greybus_trace.h"
 
 static struct kmem_cache *gb_operation_cache;
 static struct kmem_cache *gb_message_cache;
 
 /* Workqueue to handle Greybus operation completions. */
 static struct workqueue_struct *gb_operation_completion_wq;
 
 /* Wait queue for synchronous cancellations. */
 static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
 
 /*
  * Protects updates to operation->errno.
  */
 static DEFINE_SPINLOCK(gb_operations_lock);
 
 static int gb_operation_response_send(struct gb_operation *operation,
                       int errno);
 
 /*
  * Increment operation active count and add to connection list unless the
  * connection is going away.
  *
  * Caller holds operation reference.
  */
 static int gb_operation_get_active(struct gb_operation *operation)
 {
     struct gb_connection *connection = operation->connection;
     unsigned long flags;
 
     spin_lock_irqsave(&connection->lock, flags);
     switch (connection->state) {
     case GB_CONNECTION_STATE_ENABLED:
         break;
     case GB_CONNECTION_STATE_ENABLED_TX:
         if (gb_operation_is_incoming(operation))
             goto err_unlock;
         break;
     case GB_CONNECTION_STATE_DISCONNECTING:
         if (!gb_operation_is_core(operation))
             goto err_unlock;
         break;
     default:
         goto err_unlock;
     }
 
     if (operation->active++ == 0)
         list_add_tail(&operation->links, &connection->operations);
 
     trace_gb_operation_get_active(operation);
 
     spin_unlock_irqrestore(&connection->lock, flags);
 
     return 0;
 
 err_unlock:
     spin_unlock_irqrestore(&connection->lock, flags);
 
     return -ENOTCONN;
 }
 
 /* Caller holds operation reference. */
 static void gb_operation_put_active(struct gb_operation *operation)
 {
     struct gb_connection *connection = operation->connection;
     unsigned long flags;
 
     spin_lock_irqsave(&connection->lock, flags);
 
     trace_gb_operation_put_active(operation);
 
     if (--operation->active == 0) {
         list_del(&operation->links);
         if (atomic_read(&operation->waiters))
             wake_up(&gb_operation_cancellation_queue);
     }
     spin_unlock_irqrestore(&connection->lock, flags);
 }
 
 static bool gb_operation_is_active(struct gb_operation *operation)
 {
     struct gb_connection *connection = operation->connection;
     unsigned long flags;
     bool ret;
 
     spin_lock_irqsave(&connection->lock, flags);
     ret = operation->active;
     spin_unlock_irqrestore(&connection->lock, flags);
 
     return ret;
 }
 
 /*
  * Set an operation's result.
  *
  * Initially an outgoing operation's errno value is -EBADR.
  * If no error occurs before sending the request message the only
  * valid value operation->errno can be set to is -EINPROGRESS,
  * indicating the request has been (or rather is about to be) sent.
  * At that point nobody should be looking at the result until the
  * response arrives.
  *
  * The first time the result gets set after the request has been
  * sent, that result "sticks."  That is, if two concurrent threads
  * race to set the result, the first one wins.  The return value
  * tells the caller whether its result was recorded; if not the
  * caller has nothing more to do.
  *
  * The result value -EILSEQ is reserved to signal an implementation
  * error; if it's ever observed, the code performing the request has
  * done something fundamentally wrong.  It is an error to try to set
  * the result to -EBADR, and attempts to do so result in a warning,
  * and -EILSEQ is used instead.  Similarly, the only valid result
  * value to set for an operation in initial state is -EINPROGRESS.
  * Attempts to do otherwise will also record a (successful) -EILSEQ
  * operation result.
  */
 static bool gb_operation_result_set(struct gb_operation *operation, int result)
 {
     unsigned long flags;
     int prev;
 
     if (result == -EINPROGRESS) {
         /*
          * -EINPROGRESS is used to indicate the request is
          * in flight.  It should be the first result value
          * set after the initial -EBADR.  Issue a warning
          * and record an implementation error if it's
          * set at any other time.
          */
         spin_lock_irqsave(&gb_operations_lock, flags);
         prev = operation->errno;
         if (prev == -EBADR)
             operation->errno = result;
         else
             operation->errno = -EILSEQ;
         spin_unlock_irqrestore(&gb_operations_lock, flags);
         WARN_ON(prev != -EBADR);
 
         return true;
     }
 
     /*
      * The first result value set after a request has been sent
      * will be the final result of the operation.  Subsequent
      * attempts to set the result are ignored.
      *
      * Note that -EBADR is a reserved "initial state" result
      * value.  Attempts to set this value result in a warning,
      * and the result code is set to -EILSEQ instead.
      */
     if (WARN_ON(result == -EBADR))
         result = -EILSEQ; /* Nobody should be setting -EBADR */
 
     spin_lock_irqsave(&gb_operations_lock, flags);
     prev = operation->errno;
     if (prev == -EINPROGRESS)
         operation->errno = result;  /* First and final result */
     spin_unlock_irqrestore(&gb_operations_lock, flags);
 
     return prev == -EINPROGRESS;
 }
 
 int gb_operation_result(struct gb_operation *operation)
 {
     int result = operation->errno;
 
     WARN_ON(result == -EBADR);
     WARN_ON(result == -EINPROGRESS);
 
     return result;
 }
 EXPORT_SYMBOL_GPL(gb_operation_result);
 
 /*
  * Looks up an outgoing operation on a connection and returns a refcounted
  * pointer if found, or NULL otherwise.
  */
 static struct gb_operation *
 gb_operation_find_outgoing(struct gb_connection *connection, u16 operation_id)
 {
     struct gb_operation *operation;
     unsigned long flags;
     bool found = false;
 
     spin_lock_irqsave(&connection->lock, flags);
     list_for_each_entry(operation, &connection->operations, links)
         if (operation->id == operation_id &&
             !gb_operation_is_incoming(operation)) {
             gb_operation_get(operation);
             found = true;
             break;
         }
     spin_unlock_irqrestore(&connection->lock, flags);
 
     return found ? operation : NULL;
 }
 
 static int gb_message_send(struct gb_message *message, gfp_t gfp)
 {
     struct gb_connection *connection = message->operation->connection;
 
     trace_gb_message_send(message);
     return connection->hd->driver->message_send(connection->hd,
                     connection->hd_cport_id,
                     message,
                     gfp);
 }
 
 /*
  * Cancel a message we have passed to the host device layer to be sent.
  */
 static void gb_message_cancel(struct gb_message *message)
 {
     struct gb_host_device *hd = message->operation->connection->hd;
 
     hd->driver->message_cancel(message);
 }
 
 static void gb_operation_request_handle(struct gb_operation *operation)
 {
     struct gb_connection *connection = operation->connection;
     int status;
     int ret;
 
     if (connection->handler) {
         status = connection->handler(operation);
     } else {
         dev_err(&connection->hd->dev,
             "%s: unexpected incoming request of type 0x%02x\n",
             connection->name, operation->type);
 
         status = -EPROTONOSUPPORT;
     }
 
     ret = gb_operation_response_send(operation, status);
     if (ret) {
         dev_err(&connection->hd->dev,
             "%s: failed to send response %d for type 0x%02x: %d\n",
             connection->name, status, operation->type, ret);
         return;
     }
 }
 
 /*
  * Process operation work.
  *
  * For incoming requests, call the protocol request handler. The operation
  * result should be -EINPROGRESS at this point.
  *
  * For outgoing requests, the operation result value should have
  * been set before queueing this.  The operation callback function
  * allows the original requester to know the request has completed
  * and its result is available.
  */
 static void gb_operation_work(struct work_struct *work)
 {
     struct gb_operation *operation;
     int ret;
 
     operation = container_of(work, struct gb_operation, work);
 
     if (gb_operation_is_incoming(operation)) {
         gb_operation_request_handle(operation);
     } else {
         ret = del_timer_sync(&operation->timer);
         if (!ret) {
             /* Cancel request message if scheduled by timeout. */
             if (gb_operation_result(operation) == -ETIMEDOUT)
                 gb_message_cancel(operation->request);
         }
 
         operation->callback(operation);
     }
 
     gb_operation_put_active(operation);
     gb_operation_put(operation);
 }
 
 static void gb_operation_timeout(struct timer_list *t)
 {
     struct gb_operation *operation = from_timer(operation, t, timer);
 
     if (gb_operation_result_set(operation, -ETIMEDOUT)) {
         /*
          * A stuck request message will be cancelled from the
          * workqueue.
          */
         queue_work(gb_operation_completion_wq, &operation->work);
     }
 }
 
 static void gb_operation_message_init(struct gb_host_device *hd,
                       struct gb_message *message,
                       u16 operation_id,
                       size_t payload_size, u8 type)
 {
     struct gb_operation_msg_hdr *header;
 
     header = message->buffer;
 
     message->header = header;
     message->payload = payload_size ? header + 1 : NULL;
     message->payload_size = payload_size;
 
     /*
      * The type supplied for incoming message buffers will be
      * GB_REQUEST_TYPE_INVALID. Such buffers will be overwritten by
      * arriving data so there's no need to initialize the message header.
      */
     if (type != GB_REQUEST_TYPE_INVALID) {
         u16 message_size = (u16)(sizeof(*header) + payload_size);
 
         /*
          * For a request, the operation id gets filled in
          * when the message is sent.  For a response, it
          * will be copied from the request by the caller.
          *
          * The result field in a request message must be
          * zero.  It will be set just prior to sending for
          * a response.
          */
         header->size = cpu_to_le16(message_size);
         header->operation_id = 0;
         header->type = type;
         header->result = 0;
     }
 }
 
 /*
  * Allocate a message to be used for an operation request or response.
  * Both types of message contain a common header.  The request message
  * for an outgoing operation is outbound, as is the response message
  * for an incoming operation.  The message header for an outbound
  * message is partially initialized here.
  *
  * The headers for inbound messages don't need to be initialized;
  * they'll be filled in by arriving data.
  *
  * Our message buffers have the following layout:
  *  message header  \_ these combined are
  *  message payload /  the message size
  */
 static struct gb_message *
 gb_operation_message_alloc(struct gb_host_device *hd, u8 type,
                size_t payload_size, gfp_t gfp_flags)
 {
     struct gb_message *message;
     struct gb_operation_msg_hdr *header;
     size_t message_size = payload_size + sizeof(*header);
 
     if (message_size > hd->buffer_size_max) {
         dev_warn(&hd->dev, "requested message size too big (%zu > %zu)\n",
              message_size, hd->buffer_size_max);
         return NULL;
     }
 
     /* Allocate the message structure and buffer. */
     message = kmem_cache_zalloc(gb_message_cache, gfp_flags);
     if (!message)
         return NULL;
 
     message->buffer = kzalloc(message_size, gfp_flags);
     if (!message->buffer)
         goto err_free_message;
 
     /* Initialize the message.  Operation id is filled in later. */
     gb_operation_message_init(hd, message, 0, payload_size, type);
 
     return message;
 
 err_free_message:
     kmem_cache_free(gb_message_cache, message);
 
     return NULL;
 }
 
 static void gb_operation_message_free(struct gb_message *message)
 {
     kfree(message->buffer);
     kmem_cache_free(gb_message_cache, message);
 }
 
 /*
  * Map an enum gb_operation_status value (which is represented in a
  * message as a single byte) to an appropriate Linux negative errno.
  */
 static int gb_operation_status_map(u8 status)
 {
     switch (status) {
     case GB_OP_SUCCESS:
         return 0;
     case GB_OP_INTERRUPTED:
         return -EINTR;
     case GB_OP_TIMEOUT:
         return -ETIMEDOUT;
     case GB_OP_NO_MEMORY:
         return -ENOMEM;
     case GB_OP_PROTOCOL_BAD:
         return -EPROTONOSUPPORT;
     case GB_OP_OVERFLOW:
         return -EMSGSIZE;
     case GB_OP_INVALID:
         return -EINVAL;
     case GB_OP_RETRY:
         return -EAGAIN;
     case GB_OP_NONEXISTENT:
         return -ENODEV;
     case GB_OP_MALFUNCTION:
         return -EILSEQ;
     case GB_OP_UNKNOWN_ERROR:
     default:
         return -EIO;
     }
 }
 
 /*
  * Map a Linux errno value (from operation->errno) into the value
  * that should represent it in a response message status sent
  * over the wire.  Returns an enum gb_operation_status value (which
  * is represented in a message as a single byte).
  */
 static u8 gb_operation_errno_map(int errno)
 {
     switch (errno) {
     case 0:
         return GB_OP_SUCCESS;
     case -EINTR:
         return GB_OP_INTERRUPTED;
     case -ETIMEDOUT:
         return GB_OP_TIMEOUT;
     case -ENOMEM:
         return GB_OP_NO_MEMORY;
     case -EPROTONOSUPPORT:
         return GB_OP_PROTOCOL_BAD;
     case -EMSGSIZE:
         return GB_OP_OVERFLOW;  /* Could be underflow too */
     case -EINVAL:
         return GB_OP_INVALID;
     case -EAGAIN:
         return GB_OP_RETRY;
     case -EILSEQ:
         return GB_OP_MALFUNCTION;
     case -ENODEV:
         return GB_OP_NONEXISTENT;
     case -EIO:
     default:
         return GB_OP_UNKNOWN_ERROR;
     }
 }
 
 bool gb_operation_response_alloc(struct gb_operation *operation,
                  size_t response_size, gfp_t gfp)
 {
     struct gb_host_device *hd = operation->connection->hd;
     struct gb_operation_msg_hdr *request_header;
     struct gb_message *response;
     u8 type;
 
     type = operation->type | GB_MESSAGE_TYPE_RESPONSE;
     response = gb_operation_message_alloc(hd, type, response_size, gfp);
     if (!response)
         return false;
     response->operation = operation;
 
     /*
      * Size and type get initialized when the message is
      * allocated.  The errno will be set before sending.  All
      * that's left is the operation id, which we copy from the
      * request message header (as-is, in little-endian order).
      */
     request_header = operation->request->header;
     response->header->operation_id = request_header->operation_id;
     operation->response = response;
 
     return true;
 }
 EXPORT_SYMBOL_GPL(gb_operation_response_alloc);
 
 /*
  * Create a Greybus operation to be sent over the given connection.
  * The request buffer will be big enough for a payload of the given
  * size.
  *
  * For outgoing requests, the request message's header will be
  * initialized with the type of the request and the message size.
  * Outgoing operations must also specify the response buffer size,
  * which must be sufficient to hold all expected response data.  The
  * response message header will eventually be overwritten, so there's
  * no need to initialize it here.
  *
  * Request messages for incoming operations can arrive in interrupt
  * context, so they must be allocated with GFP_ATOMIC.  In this case
  * the request buffer will be immediately overwritten, so there is
  * no need to initialize the message header.  Responsibility for
  * allocating a response buffer lies with the incoming request
  * handler for a protocol.  So we don't allocate that here.
  *
  * Returns a pointer to the new operation or a null pointer if an
  * error occurs.
  */
 static struct gb_operation *
 gb_operation_create_common(struct gb_connection *connection, u8 type,
                size_t request_size, size_t response_size,
                unsigned long op_flags, gfp_t gfp_flags)
 {
     struct gb_host_device *hd = connection->hd;
     struct gb_operation *operation;
 
     operation = kmem_cache_zalloc(gb_operation_cache, gfp_flags);
     if (!operation)
         return NULL;
     operation->connection = connection;
 
     operation->request = gb_operation_message_alloc(hd, type, request_size,
                             gfp_flags);
     if (!operation->request)
         goto err_cache;
     operation->request->operation = operation;
 
     /* Allocate the response buffer for outgoing operations */
     if (!(op_flags & GB_OPERATION_FLAG_INCOMING)) {
         if (!gb_operation_response_alloc(operation, response_size,
                          gfp_flags)) {
             goto err_request;
         }
 
         timer_setup(&operation->timer, gb_operation_timeout, 0);
     }
 
     operation->flags = op_flags;
     operation->type = type;
     operation->errno = -EBADR;  /* Initial value--means "never set" */
 
     INIT_WORK(&operation->work, gb_operation_work);
     init_completion(&operation->completion);
     kref_init(&operation->kref);
     atomic_set(&operation->waiters, 0);
 
     return operation;
 
 err_request:
     gb_operation_message_free(operation->request);
 err_cache:
     kmem_cache_free(gb_operation_cache, operation);
 
     return NULL;
 }
 
 /*
  * Create a new operation associated with the given connection.  The
  * request and response sizes provided are the number of bytes
  * required to hold the request/response payload only.  Both of
  * these are allowed to be 0.  Note that 0x00 is reserved as an
  * invalid operation type for all protocols, and this is enforced
  * here.
  */
 struct gb_operation *
 gb_operation_create_flags(struct gb_connection *connection,
               u8 type, size_t request_size,
               size_t response_size, unsigned long flags,
               gfp_t gfp)
 {
     struct gb_operation *operation;
 
     if (WARN_ON_ONCE(type == GB_REQUEST_TYPE_INVALID))
         return NULL;
     if (WARN_ON_ONCE(type & GB_MESSAGE_TYPE_RESPONSE))
         type &= ~GB_MESSAGE_TYPE_RESPONSE;
 
     if (WARN_ON_ONCE(flags & ~GB_OPERATION_FLAG_USER_MASK))
         flags &= GB_OPERATION_FLAG_USER_MASK;
 
     operation = gb_operation_create_common(connection, type,
                            request_size, response_size,
                            flags, gfp);
     if (operation)
         trace_gb_operation_create(operation);
 
     return operation;
 }
 EXPORT_SYMBOL_GPL(gb_operation_create_flags);
 
 struct gb_operation *
 gb_operation_create_core(struct gb_connection *connection,
              u8 type, size_t request_size,
              size_t response_size, unsigned long flags,
              gfp_t gfp)
 {
     struct gb_operation *operation;
 
     flags |= GB_OPERATION_FLAG_CORE;
 
     operation = gb_operation_create_common(connection, type,
                            request_size, response_size,
                            flags, gfp);
     if (operation)
         trace_gb_operation_create_core(operation);
 
     return operation;
 }
 
 /* Do not export this function. */
 
 size_t gb_operation_get_payload_size_max(struct gb_connection *connection)
 {
     struct gb_host_device *hd = connection->hd;
 
     return hd->buffer_size_max - sizeof(struct gb_operation_msg_hdr);
 }
 EXPORT_SYMBOL_GPL(gb_operation_get_payload_size_max);
 
 static struct gb_operation *
 gb_operation_create_incoming(struct gb_connection *connection, u16 id,
                  u8 type, void *data, size_t size)
 {
     struct gb_operation *operation;
     size_t request_size;
     unsigned long flags = GB_OPERATION_FLAG_INCOMING;
 
     /* Caller has made sure we at least have a message header. */
     request_size = size - sizeof(struct gb_operation_msg_hdr);
 
     if (!id)
         flags |= GB_OPERATION_FLAG_UNIDIRECTIONAL;
 
     operation = gb_operation_create_common(connection, type,
                            request_size,
                            GB_REQUEST_TYPE_INVALID,
                            flags, GFP_ATOMIC);
     if (!operation)
         return NULL;
 
     operation->id = id;
     memcpy(operation->request->header, data, size);
     trace_gb_operation_create_incoming(operation);
 
     return operation;
 }
 
 /*
  * Get an additional reference on an operation.
  */
 void gb_operation_get(struct gb_operation *operation)
 {
     kref_get(&operation->kref);
 }
 EXPORT_SYMBOL_GPL(gb_operation_get);
 
 /*
  * Destroy a previously created operation.
  */
 static void _gb_operation_destroy(struct kref *kref)
 {
     struct gb_operation *operation;
 
     operation = container_of(kref, struct gb_operation, kref);
 
     trace_gb_operation_destroy(operation);
 
     if (operation->response)
         gb_operation_message_free(operation->response);
     gb_operation_message_free(operation->request);
 
     kmem_cache_free(gb_operation_cache, operation);
 }
 
 /*
  * Drop a reference on an operation, and destroy it when the last
  * one is gone.
  */
 void gb_operation_put(struct gb_operation *operation)
 {
     if (WARN_ON(!operation))
         return;
 
     kref_put(&operation->kref, _gb_operation_destroy);
 }
 EXPORT_SYMBOL_GPL(gb_operation_put);
 
 /* Tell the requester we're done */
 static void gb_operation_sync_callback(struct gb_operation *operation)
 {
     complete(&operation->completion);
 }
 
 /**
  * gb_operation_request_send() - send an operation request message
  * @operation:  the operation to initiate
  * @callback:   the operation completion callback
  * @timeout:    operation timeout in milliseconds, or zero for no timeout
  * @gfp:    the memory flags to use for any allocations
  *
  * The caller has filled in any payload so the request message is ready to go.
  * The callback function supplied will be called when the response message has
  * arrived, a unidirectional request has been sent, or the operation is
  * cancelled, indicating that the operation is complete. The callback function
  * can fetch the result of the operation using gb_operation_result() if
  * desired.
  *
  * Return: 0 if the request was successfully queued in the host-driver queues,
  * or a negative errno.
  */
 int gb_operation_request_send(struct gb_operation *operation,
                   gb_operation_callback callback,
                   unsigned int timeout,
                   gfp_t gfp)
 {
     struct gb_connection *connection = operation->connection;
     struct gb_operation_msg_hdr *header;
     unsigned int cycle;
     int ret;
 
     if (gb_connection_is_offloaded(connection))
         return -EBUSY;
 
     if (!callback)
         return -EINVAL;
 
     /*
      * Record the callback function, which is executed in
      * non-atomic (workqueue) context when the final result
      * of an operation has been set.
      */
     operation->callback = callback;
 
     /*
      * Assign the operation's id, and store it in the request header.
      * Zero is a reserved operation id for unidirectional operations.
      */
     if (gb_operation_is_unidirectional(operation)) {
         operation->id = 0;
     } else {
         cycle = (unsigned int)atomic_inc_return(&connection->op_cycle);
         operation->id = (u16)(cycle % U16_MAX + 1);
     }
 
     header = operation->request->header;
     header->operation_id = cpu_to_le16(operation->id);
 
     gb_operation_result_set(operation, -EINPROGRESS);
 
     /*
      * Get an extra reference on the operation. It'll be dropped when the
      * operation completes.
      */
     gb_operation_get(operation);
     ret = gb_operation_get_active(operation);
     if (ret)
         goto err_put;
 
     ret = gb_message_send(operation->request, gfp);
     if (ret)
         goto err_put_active;
 
     if (timeout) {
         operation->timer.expires = jiffies + msecs_to_jiffies(timeout);
         add_timer(&operation->timer);
     }
 
     return 0;
 
 err_put_active:
     gb_operation_put_active(operation);
 err_put:
     gb_operation_put(operation);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(gb_operation_request_send);
 
 /*
  * Send a synchronous operation.  This function is expected to
  * block, returning only when the response has arrived, (or when an
  * error is detected.  The return value is the result of the
  * operation.
  */
 int gb_operation_request_send_sync_timeout(struct gb_operation *operation,
                        unsigned int timeout)
 {
     int ret;
 
     ret = gb_operation_request_send(operation, gb_operation_sync_callback,
                     timeout, GFP_KERNEL);
     if (ret)
         return ret;
 
     ret = wait_for_completion_interruptible(&operation->completion);
     if (ret < 0) {
         /* Cancel the operation if interrupted */
         gb_operation_cancel(operation, -ECANCELED);
     }
 
     return gb_operation_result(operation);
 }
 EXPORT_SYMBOL_GPL(gb_operation_request_send_sync_timeout);
 
 /*
  * Send a response for an incoming operation request.  A non-zero
  * errno indicates a failed operation.
  *
  * If there is any response payload, the incoming request handler is
  * responsible for allocating the response message.  Otherwise the
  * it can simply supply the result errno; this function will
  * allocate the response message if necessary.
  */
 static int gb_operation_response_send(struct gb_operation *operation,
                       int errno)
 {
     struct gb_connection *connection = operation->connection;
     int ret;
 
     if (!operation->response &&
         !gb_operation_is_unidirectional(operation)) {
         if (!gb_operation_response_alloc(operation, 0, GFP_KERNEL))
             return -ENOMEM;
     }
 
     /* Record the result */
     if (!gb_operation_result_set(operation, errno)) {
         dev_err(&connection->hd->dev, "request result already set\n");
         return -EIO;    /* Shouldn't happen */
     }
 
     /* Sender of request does not care about response. */
     if (gb_operation_is_unidirectional(operation))
         return 0;
 
     /* Reference will be dropped when message has been sent. */
     gb_operation_get(operation);
     ret = gb_operation_get_active(operation);
     if (ret)
         goto err_put;
 
     /* Fill in the response header and send it */
     operation->response->header->result = gb_operation_errno_map(errno);
 
     ret = gb_message_send(operation->response, GFP_KERNEL);
     if (ret)
         goto err_put_active;
 
     return 0;
 
 err_put_active:
     gb_operation_put_active(operation);
 err_put:
     gb_operation_put(operation);
 
     return ret;
 }
 
 /*
  * This function is called when a message send request has completed.
  */
 void greybus_message_sent(struct gb_host_device *hd,
               struct gb_message *message, int status)
 {
     struct gb_operation *operation = message->operation;
     struct gb_connection *connection = operation->connection;
 
     /*
      * If the message was a response, we just need to drop our
      * reference to the operation.  If an error occurred, report
      * it.
      *
      * For requests, if there's no error and the operation in not
      * unidirectional, there's nothing more to do until the response
      * arrives. If an error occurred attempting to send it, or if the
      * operation is unidrectional, record the result of the operation and
      * schedule its completion.
      */
     if (message == operation->response) {
         if (status) {
             dev_err(&connection->hd->dev,
                 "%s: error sending response 0x%02x: %d\n",
                 connection->name, operation->type, status);
         }
 
         gb_operation_put_active(operation);
         gb_operation_put(operation);
     } else if (status || gb_operation_is_unidirectional(operation)) {
         if (gb_operation_result_set(operation, status)) {
             queue_work(gb_operation_completion_wq,
                    &operation->work);
         }
     }
 }
 EXPORT_SYMBOL_GPL(greybus_message_sent);
 
 /*
  * We've received data on a connection, and it doesn't look like a
  * response, so we assume it's a request.
  *
  * This is called in interrupt context, so just copy the incoming
  * data into the request buffer and handle the rest via workqueue.
  */
 static void gb_connection_recv_request(struct gb_connection *connection,
                 const struct gb_operation_msg_hdr *header,
                 void *data, size_t size)
 {
     struct gb_operation *operation;
     u16 operation_id;
     u8 type;
     int ret;
 
     operation_id = le16_to_cpu(header->operation_id);
     type = header->type;
 
     operation = gb_operation_create_incoming(connection, operation_id,
                          type, data, size);
     if (!operation) {
         dev_err(&connection->hd->dev,
             "%s: can't create incoming operation\n",
             connection->name);
         return;
     }
 
     ret = gb_operation_get_active(operation);
     if (ret) {
         gb_operation_put(operation);
         return;
     }
     trace_gb_message_recv_request(operation->request);
 
     /*
      * The initial reference to the operation will be dropped when the
      * request handler returns.
      */
     if (gb_operation_result_set(operation, -EINPROGRESS))
         queue_work(connection->wq, &operation->work);
 }
 
 /*
  * We've received data that appears to be an operation response
  * message.  Look up the operation, and record that we've received
  * its response.
  *
  * This is called in interrupt context, so just copy the incoming
  * data into the response buffer and handle the rest via workqueue.
  */
 static void gb_connection_recv_response(struct gb_connection *connection,
                 const struct gb_operation_msg_hdr *header,
                 void *data, size_t size)
 {
     struct gb_operation *operation;
     struct gb_message *message;
     size_t message_size;
     u16 operation_id;
     int errno;
 
     operation_id = le16_to_cpu(header->operation_id);
 
     if (!operation_id) {
         dev_err_ratelimited(&connection->hd->dev,
                     "%s: invalid response id 0 received\n",
                     connection->name);
         return;
     }
 
     operation = gb_operation_find_outgoing(connection, operation_id);
     if (!operation) {
         dev_err_ratelimited(&connection->hd->dev,
                     "%s: unexpected response id 0x%04x received\n",
                     connection->name, operation_id);
         return;
     }
 
     errno = gb_operation_status_map(header->result);
     message = operation->response;
     message_size = sizeof(*header) + message->payload_size;
     if (!errno && size > message_size) {
         dev_err_ratelimited(&connection->hd->dev,
                     "%s: malformed response 0x%02x received (%zu > %zu)\n",
                     connection->name, header->type,
                     size, message_size);
         errno = -EMSGSIZE;
     } else if (!errno && size < message_size) {
         if (gb_operation_short_response_allowed(operation)) {
             message->payload_size = size - sizeof(*header);
         } else {
             dev_err_ratelimited(&connection->hd->dev,
                         "%s: short response 0x%02x received (%zu < %zu)\n",
                         connection->name, header->type,
                         size, message_size);
             errno = -EMSGSIZE;
         }
     }
 
     /* We must ignore the payload if a bad status is returned */
     if (errno)
         size = sizeof(*header);
 
     /* The rest will be handled in work queue context */
     if (gb_operation_result_set(operation, errno)) {
         memcpy(message->buffer, data, size);
 
         trace_gb_message_recv_response(message);
 
         queue_work(gb_operation_completion_wq, &operation->work);
     }
 
     gb_operation_put(operation);
 }
 
 /*
  * Handle data arriving on a connection.  As soon as we return the
  * supplied data buffer will be reused (so unless we do something
  * with, it's effectively dropped).
  */
 void gb_connection_recv(struct gb_connection *connection,
             void *data, size_t size)
 {
     struct gb_operation_msg_hdr header;
     struct device *dev = &connection->hd->dev;
     size_t msg_size;
 
     if (connection->state == GB_CONNECTION_STATE_DISABLED ||
         gb_connection_is_offloaded(connection)) {
         dev_warn_ratelimited(dev, "%s: dropping %zu received bytes\n",
                      connection->name, size);
         return;
     }
 
     if (size < sizeof(header)) {
         dev_err_ratelimited(dev, "%s: short message received\n",
                     connection->name);
         return;
     }
 
     /* Use memcpy as data may be unaligned */
     memcpy(&header, data, sizeof(header));
     msg_size = le16_to_cpu(header.size);
     if (size < msg_size) {
         dev_err_ratelimited(dev,
                     "%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
                     connection->name,
                     le16_to_cpu(header.operation_id),
                     header.type, size, msg_size);
         return;     /* XXX Should still complete operation */
     }
 
     if (header.type & GB_MESSAGE_TYPE_RESPONSE) {
         gb_connection_recv_response(connection, &header, data,
                         msg_size);
     } else {
         gb_connection_recv_request(connection, &header, data,
                        msg_size);
     }
 }
 
 /*
  * Cancel an outgoing operation synchronously, and record the given error to
  * indicate why.
  */
 void gb_operation_cancel(struct gb_operation *operation, int errno)
 {
     if (WARN_ON(gb_operation_is_incoming(operation)))
         return;
 
     if (gb_operation_result_set(operation, errno)) {
         gb_message_cancel(operation->request);
         queue_work(gb_operation_completion_wq, &operation->work);
     }
     trace_gb_message_cancel_outgoing(operation->request);
 
     atomic_inc(&operation->waiters);
     wait_event(gb_operation_cancellation_queue,
            !gb_operation_is_active(operation));
     atomic_dec(&operation->waiters);
 }
 EXPORT_SYMBOL_GPL(gb_operation_cancel);
 
 /*
  * Cancel an incoming operation synchronously. Called during connection tear
  * down.
  */
 void gb_operation_cancel_incoming(struct gb_operation *operation, int errno)
 {
     if (WARN_ON(!gb_operation_is_incoming(operation)))
         return;
 
     if (!gb_operation_is_unidirectional(operation)) {
         /*
          * Make sure the request handler has submitted the response
          * before cancelling it.
          */
         flush_work(&operation->work);
         if (!gb_operation_result_set(operation, errno))
             gb_message_cancel(operation->response);
     }
     trace_gb_message_cancel_incoming(operation->response);
 
     atomic_inc(&operation->waiters);
     wait_event(gb_operation_cancellation_queue,
            !gb_operation_is_active(operation));
     atomic_dec(&operation->waiters);
 }
 
 /**
  * gb_operation_sync_timeout() - implement a "simple" synchronous operation
  * @connection: the Greybus connection to send this to
  * @type: the type of operation to send
  * @request: pointer to a memory buffer to copy the request from
  * @request_size: size of @request
  * @response: pointer to a memory buffer to copy the response to
  * @response_size: the size of @response.
  * @timeout: operation timeout in milliseconds
  *
  * This function implements a simple synchronous Greybus operation.  It sends
  * the provided operation request and waits (sleeps) until the corresponding
  * operation response message has been successfully received, or an error
  * occurs.  @request and @response are buffers to hold the request and response
  * data respectively, and if they are not NULL, their size must be specified in
  * @request_size and @response_size.
  *
  * If a response payload is to come back, and @response is not NULL,
  * @response_size number of bytes will be copied into @response if the operation
  * is successful.
  *
  * If there is an error, the response buffer is left alone.
  */
 int gb_operation_sync_timeout(struct gb_connection *connection, int type,
                   void *request, int request_size,
                   void *response, int response_size,
                   unsigned int timeout)
 {
     struct gb_operation *operation;
     int ret;
 
     if ((response_size && !response) ||
         (request_size && !request))
         return -EINVAL;
 
     operation = gb_operation_create(connection, type,
                     request_size, response_size,
                     GFP_KERNEL);
     if (!operation)
         return -ENOMEM;
 
     if (request_size)
         memcpy(operation->request->payload, request, request_size);
 
     ret = gb_operation_request_send_sync_timeout(operation, timeout);
     if (ret) {
         dev_err(&connection->hd->dev,
             "%s: synchronous operation id 0x%04x of type 0x%02x failed: %d\n",
             connection->name, operation->id, type, ret);
     } else {
         if (response_size) {
             memcpy(response, operation->response->payload,
                    response_size);
         }
     }
 
     gb_operation_put(operation);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(gb_operation_sync_timeout);
 
 /**
  * gb_operation_unidirectional_timeout() - initiate a unidirectional operation
  * @connection:     connection to use
  * @type:       type of operation to send
  * @request:        memory buffer to copy the request from
  * @request_size:   size of @request
  * @timeout:        send timeout in milliseconds
  *
  * Initiate a unidirectional operation by sending a request message and
  * waiting for it to be acknowledged as sent by the host device.
  *
  * Note that successful send of a unidirectional operation does not imply that
  * the request as actually reached the remote end of the connection.
  */
 int gb_operation_unidirectional_timeout(struct gb_connection *connection,
                     int type, void *request,
                     int request_size,
                     unsigned int timeout)
 {
     struct gb_operation *operation;
     int ret;
 
     if (request_size && !request)
         return -EINVAL;
 
     operation = gb_operation_create_flags(connection, type,
                           request_size, 0,
                           GB_OPERATION_FLAG_UNIDIRECTIONAL,
                           GFP_KERNEL);
     if (!operation)
         return -ENOMEM;
 
     if (request_size)
         memcpy(operation->request->payload, request, request_size);
 
     ret = gb_operation_request_send_sync_timeout(operation, timeout);
     if (ret) {
         dev_err(&connection->hd->dev,
             "%s: unidirectional operation of type 0x%02x failed: %d\n",
             connection->name, type, ret);
     }
 
     gb_operation_put(operation);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(gb_operation_unidirectional_timeout);
 
 int __init gb_operation_init(void)
 {
     gb_message_cache = kmem_cache_create("gb_message_cache",
                          sizeof(struct gb_message), 0, 0,
                          NULL);
     if (!gb_message_cache)
         return -ENOMEM;
 
     gb_operation_cache = kmem_cache_create("gb_operation_cache",
                            sizeof(struct gb_operation), 0,
                            0, NULL);
     if (!gb_operation_cache)
         goto err_destroy_message_cache;
 
     gb_operation_completion_wq = alloc_workqueue("greybus_completion",
                              0, 0);
     if (!gb_operation_completion_wq)
         goto err_destroy_operation_cache;
 
     return 0;
 
 err_destroy_operation_cache:
     kmem_cache_destroy(gb_operation_cache);
     gb_operation_cache = NULL;
 err_destroy_message_cache:
     kmem_cache_destroy(gb_message_cache);
     gb_message_cache = NULL;
 
     return -ENOMEM;
 }
 
 void gb_operation_exit(void)
 {
     destroy_workqueue(gb_operation_completion_wq);
     gb_operation_completion_wq = NULL;
     kmem_cache_destroy(gb_operation_cache);
     gb_operation_cache = NULL;
     kmem_cache_destroy(gb_message_cache);
     gb_message_cache = NULL;
 }

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