Programming the Microsoft® Windows® Driver Model

Author Walter Oney Pages 640 Disk 1 Companion CD(s) Level Intermediate Published 10/13/1999 ISBN 9780735605886 ISBN-10 0-7356-0588-2 Price(USD) $49.99 To see this book's discounted price, select a reseller below.	More Information About the Book Table of Contents Sample Chapter Index Related Series Related Books About the Author Support: Book & CD Rate this book

Chapter 5: The I/O Request Packet

• The I/O Request Packet
• Data Structures
• Structure of an IRP
• The I/O Stack
• The "Standard Model" for IRP Processing
• Creating an IRP
• Forwarding to a Dispatch Routine
• Duties of a Dispatch Routine
• The StartIo Routine
• The Interrupt Service Routine
• Deferred Procedure Call Routine
• Custom Queues
• Completing I/O Requests
• Completion Mechanics
• Using Completion Routines
• How Completion Routines Get Called
• Why Completion Routines Call IoMarkIrpPending
• Passing Requests Down to Lower Levels
• Cancelling I/O Requests
• If It Weren't for Multitasking…
• Synchronizing Cancellation
• Case 1: CPU A Gets the Spin Lock First
• Case 2: CPU B Gets the Spin Lock Just Before CPU A Tries
• Case 3: CPU B Gets the Spin Lock Twice
• Managing Your Own IRPs
• Using IoBuildSynchronousFsdRequest
• Cleaning Up
• Cancelling a Synchronous IRP
• Using IoAllocateIrp
• Loose Ends
• Using IoBuildDeviceIoControlRequest
• Using IoBuildAsynchronousFsdRequest
• Where Do Device Object Pointers Come From?

The I/O Request Packet

The operating system uses a data structure known as an I/O request packet, or IRP, to communicate with a kernel-mode device driver. In this chapter, I'll discuss this important data structure and the means by which it's created, sent, processed, and ultimately destroyed. I'll end with a discussion of the relatively complex subject of IRP cancellation. This chapter is rather abstract, I'm afraid, because I haven't yet talked about any of the concepts that surround specific types of IRPs. You might, therefore, want to skim this chapter and refer back to it while you're reading later chapters.