Method of using collaborative spinlocks to provide exclusive access to a resource in a multiprocessor computer system

In a multiprocessor computing system having memory shared by all processors of the computing system and including a symmetric multiprocessor (SMP) operating system, a method for protecting the execution state of a device driver written to run in a uniprocessor environment using a interrupt time spinlock and a task time spinlock, comprising the steps of:

• at task time, determining whether the task time spinlock can be acquired by the operating system;
• if, at task time, the task time spinlock can be acquired by the operating system, having the operating system acquire the task time spinlock and then wait to call the device driver until the interrupt time spinlock is unowned;
• at interrupt time, determining whether the interrupt time spinlock can be acquired by the operating system;
• and
• if, at interrupt time, the interrupt time spinlock can be acquired by the operating system, having the operating system acquire the interrupt time spinlock and then wait to call the device driver until the task time spinlock is unowned or, if the task time spinlock is owned, the processor owning the task time spinlock is placed in a predetermined condition.

In a multiprocessor computing system having memory shared by all processors of the computing system and including a symmetric multiprocessor (SMP) operating system, a method operative at task time for protecting the execution state of a device driver written to run in a uniprocessor environment using a interrupt time spinlock and a task time spinlock, comprising the steps of:

• determining whether the task time spinlock can be acquired by the operating system;
• if the task time spinlock cannot be acquired by the operating system, placing the task time spinlock in a spin on read condition;
• if the task time spinlock can be acquired by the operating system, having the operating system acquire the task time spinlock;
• determining whether the interrupt time spinlock is owned by another processor;
• if the interrupt time spinlock is unowned, having the operating system call the device driver.

In a multiprocessor computing system having memory shared by all processors of the computing system and including a symmetric multiprocessor (SMP) operating system, a method operative at interrupt time for protecting the execution state of a device driver written to run in a uniprocessor environment using a interrupt time spinlock and a task time spinlock, comprising the steps of:

• determining whether the interrupt time spinlock can be acquired by the operating system;
• if the interrupt time spinlock cannot be acquired by the operating system, placing the interrupt time spinlock in a spin on read condition;
• if the interrupt time spinlock can be acquired by the operating system, determining whether the task time spinlock is owned by a given processor;
• if the task time spinlock is owned by the given processor, placing the given processor in a predetermined condition;
• and
• having the operating system call the device driver.

A computer program product in a computer-readable medium for use in a multiprocessor computing system having memory shared by all processors of the computing system and including an operating system, the computer program product for protecting the execution state of a device driver written to run in a uniprocessor environment, comprising:

• an interrupt time spinlock;
• a task time spinlock;
• first code means, operative at task time and prior to calling the kernel extension, for controlling the operating system to acquire the task time spinlock and then to wait to call the kernel extension until the interrupt time spinlock is unowned;
• and
• second code means, operative at interrupt time and prior to calling the kernel extension, for controlling the operating system to acquire the interrupt time spinlock and then to wait to call the kernel extension until either the task time spinlock is unowned or, if the task time spinlock is owned, a processor owning the task time spinlock is placed in a predetermined condition.

A computer system, comprising:

• a plurality of processors;
• a symmetric multiprocessing (SMP) operating system;
• at least one external device;
• a device driver for controlling the at least one external device;
• and
• means for preventing concurrent access to the device driver by the plurality of processors, the preventing means comprising:
• an interrupt time spinlock;
• a task time spinlock;
• first code means, operative at task time and prior to calling the kernel extension, for controlling the operating system to acquire the task time spinlock and then to wait to call the kernel extension until the interrupt time spinlock is unowned;
• and
• second code means, operative at interrupt time and prior to calling the kernel extension, for controlling the operating system to acquire the interrupt time spinlock and then to wait to call the kernel extension until either the task time spinlock is unowned or, if the task time spinlock is owned, a processor owning the task time spinlock is placed in a predetermined condition.

A computer program product in a computer-readable medium for use in a multiprocessor computing system having an operating system and at least one resource, the computer program product for protecting the execution state of the resource, comprising:

• a first spinlock;
• a second spinlock;
• first code means, operative at a task time and prior to calling the resource, for controlling the operating system to acquire the second spinlock and then to wait to call the resource until the first spinlock is unowned;
• and
• second code means, operative at an interrupt time and prior to calling the resource, for controlling the operating system to acquire the first spinlock and then to wait to call the resource until either the second spinlock is unowned or, if the second spinlock is owned, a processor owning the second spinlock is placed in a predetermined condition.