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genode/repos/os/include/block/component.h

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/*
* \brief Block-session component
* \author Christian Helmuth
* \author Stefan Kalkowski
* \date 2011-05-20
*/
/*
* Copyright (C) 2011-2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__BLOCK__COMPONENT_H_
#define _INCLUDE__BLOCK__COMPONENT_H_
#include <root/component.h>
#include <os/signal_rpc_dispatcher.h>
#include <os/server.h>
#include <block/driver.h>
namespace Block {
using namespace Genode;
class Session_component_base;
class Session_component;
class Root;
};
/**
* We have a hen and egg situation that makes this base class necessary.
* The Block::Session_rpc_object construction depends on a dataspace for
* the packet stream. The dataspace on the other hand is constructed by
* the driver, which is created on demand when creating a session.
* When creating the driver, and dataspace outside the Session_component
* constructor within _create_session of the root component, we would have
* to destroy the driver and dataspace within the destructor body of
* Session_component, which will lead to problems, because the packet stream
* destructors will be called after the shared memory already vanished.
*/
class Block::Session_component_base
{
protected:
Driver_factory &_driver_factory;
Driver &_driver;
Ram_dataspace_capability _rq_ds;
Session_component_base(Driver_factory &factory, size_t tx_buf_size)
: _driver_factory(factory),
_driver(*factory.create()),
_rq_ds(_driver.alloc_dma_buffer(tx_buf_size)) {}
~Session_component_base()
{
_driver.free_dma_buffer(_rq_ds);
_driver_factory.destroy(&_driver);
}
};
class Block::Session_component : public Block::Session_component_base,
public Block::Driver_session
{
private:
addr_t _rq_phys;
Signal_rpc_member<Session_component> _sink_ack;
Signal_rpc_member<Session_component> _sink_submit;
bool _req_queue_full;
bool _ack_queue_full;
Packet_descriptor _p_to_handle;
unsigned _p_in_fly;
/**
* Acknowledge a packet already handled
*/
inline void _ack_packet(Packet_descriptor &packet)
{
if (!tx_sink()->ready_to_ack())
PERR("Not ready to ack!");
tx_sink()->acknowledge_packet(packet);
_p_in_fly--;
}
/**
* Range check packet request
*/
inline bool _range_check(Packet_descriptor &p) {
return p.block_number() + p.block_count() - 1
< _driver.block_count(); }
/**
* Handle a single request
*/
void _handle_packet(Packet_descriptor packet)
{
_p_to_handle = packet;
_p_to_handle.succeeded(false);
/* ignore invalid packets */
if (!packet.valid() || !_range_check(_p_to_handle)) {
_ack_packet(_p_to_handle);
return;
}
try {
switch (_p_to_handle.operation()) {
case Block::Packet_descriptor::READ:
if (_driver.dma_enabled())
_driver.read_dma(packet.block_number(),
packet.block_count(),
_rq_phys + packet.offset(),
_p_to_handle);
else
_driver.read(packet.block_number(),
packet.block_count(),
tx_sink()->packet_content(packet),
_p_to_handle);
break;
case Block::Packet_descriptor::WRITE:
if (_driver.dma_enabled())
_driver.write_dma(packet.block_number(),
packet.block_count(),
_rq_phys + packet.offset(),
_p_to_handle);
else
_driver.write(packet.block_number(),
packet.block_count(),
tx_sink()->packet_content(packet),
_p_to_handle);
break;
default:
throw Driver::Io_error();
}
} catch (Driver::Request_congestion) {
_req_queue_full = true;
} catch (Driver::Io_error) {
_ack_packet(_p_to_handle);
}
}
/**
* Triggered when a packet was placed into the empty submit queue
*/
void _packet_avail(unsigned)
{
/*
* as long as more packets are available, and we're able to ack
* them, and the driver's request queue isn't full,
* direct the packet request to the driver backend
*/
for (_ack_queue_full = (_p_in_fly >= tx_sink()->ack_slots_free());
!_req_queue_full && !_ack_queue_full
&& tx_sink()->packet_avail();
_ack_queue_full = (++_p_in_fly >= tx_sink()->ack_slots_free()))
_handle_packet(tx_sink()->get_packet());
}
/**
* Triggered when an ack got removed from the full ack queue
*/
void _ready_to_ack(unsigned) { _packet_avail(0); }
public:
/**
* Constructor
*
* \param rq_ds shared dataspace for packet stream
* \param driver block driver backend
* \param driver_factory factory to create and destroy driver objects
* \param ep entrypoint handling this session component
*/
Session_component(Driver_factory &driver_factory,
Server::Entrypoint &ep, size_t buf_size)
: Session_component_base(driver_factory, buf_size),
Driver_session(_rq_ds, ep.rpc_ep()),
_rq_phys(Dataspace_client(_rq_ds).phys_addr()),
_sink_ack(ep, *this, &Session_component::_ready_to_ack),
_sink_submit(ep, *this, &Session_component::_packet_avail),
_req_queue_full(false),
_p_in_fly(0)
{
_tx.sigh_ready_to_ack(_sink_ack);
_tx.sigh_packet_avail(_sink_submit);
_driver.session(this);
}
~Session_component() { _driver.session(nullptr); }
/**
* Acknowledges a packet processed by the driver to the client
*
* \param packet the packet to acknowledge
* \param success indicated whether the processing was successful
*
* \throw Ack_congestion
*/
void ack_packet(Packet_descriptor &packet, bool success)
{
packet.succeeded(success);
_ack_packet(packet);
if (!_req_queue_full && !_ack_queue_full)
return;
/*
* when the driver's request queue was full,
* handle last unprocessed packet taken out of submit queue
*/
if (_req_queue_full) {
_req_queue_full = false;
_handle_packet(_p_to_handle);
}
/* resume packet processing */
_packet_avail(0);
}
/*******************************
** Block session interface **
*******************************/
void info(sector_t *blk_count, size_t *blk_size,
Operations *ops)
{
*blk_count = _driver.block_count();
*blk_size = _driver.block_size();
*ops = _driver.ops();
}
void sync() { _driver.sync(); }
};
/**
* Root component, handling new session requests
*/
class Block::Root : public Genode::Root_component<Block::Session_component,
Single_client>
{
private:
Driver_factory &_driver_factory;
Server::Entrypoint &_ep;
protected:
/**
* Always returns the singleton block-session component
*/
Session_component *_create_session(const char *args)
{
size_t ram_quota =
Arg_string::find_arg(args, "ram_quota" ).ulong_value(0);
size_t tx_buf_size =
Arg_string::find_arg(args, "tx_buf_size").ulong_value(0);
/* delete ram quota by the memory needed for the session */
size_t session_size = max((size_t)4096,
sizeof(Session_component)
+ sizeof(Allocator_avl));
if (ram_quota < session_size)
throw Root::Quota_exceeded();
/*
* Check if donated ram quota suffices for both
* communication buffers. Also check both sizes separately
* to handle a possible overflow of the sum of both sizes.
*/
if (tx_buf_size > ram_quota - session_size) {
PERR("insufficient 'ram_quota', got %zd, need %zd",
ram_quota, tx_buf_size + session_size);
throw Root::Quota_exceeded();
}
return new (md_alloc()) Session_component(_driver_factory,
_ep, tx_buf_size);
}
public:
/**
* Constructor
*
* \param ep entrypoint handling this root component
* \param md_alloc allocator to allocate session components
* \param driver_factory factory to create and destroy driver backend
* \param receiver signal receiver managing signals of the client
*/
Root(Server::Entrypoint &ep, Allocator *md_alloc,
Driver_factory &driver_factory)
: Root_component(&ep.rpc_ep(), md_alloc),
_driver_factory(driver_factory), _ep(ep) { }
};
#endif /* _INCLUDE__BLOCK__COMPONENT_H_ */
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