- FreeBSD Device Drivers
- About the Technical Reviewer
- Foreword
- Acknowledgments
- Introduction
- 1. Building and Running Modules
- 2. Allocating Memory
- 3. Device Communication and Control
- 4. Thread Synchronization
- A Simple Synchronization Problem
- A More Complex Synchronization Problem
- Preventing Race Conditions
- Mutexes
- Mutex Management Routines
- Implementing Mutexes
- Shared/Exclusive Locks
- Shared/Exclusive Lock Management Routines
- Implementing Shared/Exclusive Locks
- Reader/Writer Locks
- Reader/Writer Lock Management Routines
- Condition Variables
- Condition Variable Management Routines
- General Guidelines
- Conclusion
- 5. Delaying Execution
- 6. Case Study: Virtual Null Modem
- 7. Newbus and Resource Allocation
- 8. Interrupt Handling
- 9. Case Study: Parallel Port Printer Driver
- Code Analysis
- lpt_identify Function
- lpt_probe Function
- lpt_detect Function
- lpt_port_test Function
- lpt_attach Function
- lpt_detach Function
- lpt_open Function
- lpt_read Function
- lpt_write Function
- lpt_intr Function
- lpt_timeout Function
- lpt_push_bytes Function
- lpt_close Function
- lpt_ioctl Function
- lpt_request_ppbus Function
- lpt_release_ppbus Function
- Conclusion
- Code Analysis
- 10. Managing and Using Resources
- 11. Case Study: Intelligent Platform Management Interface Driver
- 12. Direct Memory Access
- 13. Storage Drivers
- 14. Common Access Method
- 15. USB Drivers
- About USB Devices
- More About USB Devices
- USB Configuration Structures
- USB Transfers (in FreeBSD)
- USB Configuration Structure Management Routines
- USB Methods Structure
- Tying Everything Together
- ulpt_probe Function
- ulpt_attach Function
- ulpt_detach Function
- ulpt_open Function
- ulpt_reset Function
- unlpt_open Function
- ulpt_close Function
- ulpt_ioctl Function
- ulpt_watchdog Function
- ulpt_start_read Function
- ulpt_stop_read Function
- ulpt_start_write Function
- ulpt_stop_write Function
- ulpt_write_callback Function
- ulpt_read_callback Function
- ulpt_status_callback Function
- Conclusion
- 16. Network Drivers, Part 1: Data Structures
- 17. Network Drivers, Part 2: Packet Reception and Transmission
- References
- Index
- About the Author
- Colophon
- A. UPDATES
As seen in the previous section, after processing a block-centric I/O request, you must inform the kernel with:
#include <sys/bio.h> void biodone(struct bio *bp); void biofinish(struct bio *bp, struct devstat *stat, int error);
The biodone function tells the kernel that the block-centric I/O request bp has been serviced successfully.
The biofinish function is identical to biodone, except that it sets bp to return the error code error (that is to say, biofinish can tell the kernel that bp was invalid, successful, or unsuccessful).
Note
Typically, the stat argument is set to NULL. For more on struct devstat, see the devstat(9) manual page (though it’s somewhat antiquated).
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