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Kernel: Implement an asynchronous device request stack

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This allows issuing asynchronous requests for devices and waiting
on the completion of the request. The requests can cascade into
multiple sub-requests.

Since IRQs may complete at any time, if the current process is no
longer the same that started the process, we need to swich the
paging context before accessing user buffers.

Change the PATA driver to use this model.
This commit is contained in:
Tom 2020-11-02 11:16:01 -07:00 • committed by Andreas Kling
parent 96081010dc
commit 2fd5ce1eb0
17 changed files with 804 additions and 246 deletions
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24
Kernel/Devices/Device.h
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@ -34,10 +34,12 @@
// There are two main subclasses:
// - BlockDevice (random access)
// - CharacterDevice (sequential)
#include <AK/DoublyLinkedList.h>
#include <AK/Function.h>
#include <AK/HashMap.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Devices/AsyncDeviceRequest.h>
#include <Kernel/FileSystem/File.h>
#include <Kernel/Lock.h>
#include <Kernel/UnixTypes.h>
namespace Kernel {
@ -61,6 +63,23 @@ public:
static void for_each(Function<void(Device&)>);
static Device* get_device(unsigned major, unsigned minor);
void process_next_queued_request(Badge<AsyncDeviceRequest>, const AsyncDeviceRequest&);
template<typename AsyncRequestType, typename... Args>
NonnullRefPtr<AsyncRequestType> make_request(Args&&... args)
{
auto request = adopt(*new AsyncRequestType(*this, forward<Args>(args)...));
bool was_empty;
{
ScopedSpinLock lock(m_requests_lock);
was_empty = m_requests.is_empty();
m_requests.append(request);
}
if (was_empty)
request->do_start({});
return request;
}
protected:
Device(unsigned major, unsigned minor);
void set_uid(uid_t uid) { m_uid = uid; }
@ -73,6 +92,9 @@ private:
unsigned m_minor { 0 };
uid_t m_uid { 0 };
gid_t m_gid { 0 };
SpinLock<u8> m_requests_lock;
DoublyLinkedList<RefPtr<AsyncDeviceRequest>> m_requests;
};
}