Merge pull request #360 from olshevskiy87/fix_typos_interrupts

fix typos: 'interrupts' chapter

interrupts/interrupts-1.md

@@ -227,7 +227,7 @@ And the last `Type` field describes the type of the `IDT` entry. There are three
 * Trap gate
 * Task gate
 
-The `IST` or `Interrupt Stack Table` is a new mechanism in the `x86_64`. It is used as an alternative to the the legacy stack-switch mechanism. Previously The `x86` architecture provided a mechanism to automatically switch stack frames in response to an interrupt. The `IST` is a modified version of the `x86` Stack switching mode. This mechanism unconditionally switches stacks when it is enabled and can be enabled for any interrupt in the `IDT` entry related with the certain interrupt (we will soon see it). From this we can understand that `IST` is not necessary for all interrupts. Some interrupts can continue to use the legacy stack switching mode. The `IST` mechanism provides up to seven `IST` pointers in the [Task State Segment](http://en.wikipedia.org/wiki/Task_state_segment) or `TSS` which is the special structure which contains information about a process. The `TSS` is used for stack switching during the execution of an interrupt or exception handler in the Linux kernel. Each pointer is referenced by an interrupt gate from the `IDT`.
+The `IST` or `Interrupt Stack Table` is a new mechanism in the `x86_64`. It is used as an alternative to the legacy stack-switch mechanism. Previously The `x86` architecture provided a mechanism to automatically switch stack frames in response to an interrupt. The `IST` is a modified version of the `x86` Stack switching mode. This mechanism unconditionally switches stacks when it is enabled and can be enabled for any interrupt in the `IDT` entry related with the certain interrupt (we will soon see it). From this we can understand that `IST` is not necessary for all interrupts. Some interrupts can continue to use the legacy stack switching mode. The `IST` mechanism provides up to seven `IST` pointers in the [Task State Segment](http://en.wikipedia.org/wiki/Task_state_segment) or `TSS` which is the special structure which contains information about a process. The `TSS` is used for stack switching during the execution of an interrupt or exception handler in the Linux kernel. Each pointer is referenced by an interrupt gate from the `IDT`.
 
 The `Interrupt Descriptor Table` represented by the array of the `gate_desc` structures:
 

interrupts/interrupts-10.md

@@ -179,7 +179,7 @@ Now let's look at the calls of the `request_irq` functions in our example. As we
 #define _DC21285_IRQ(x)         (16 + (x))
 ```
 
-The [ISA](https://en.wikipedia.org/wiki/Industry_Standard_Architecture) IRQs on this board are from `0` to `15`, so, our interrupts will have first two numbers: `16` and `17`. Second parameters for two calls of the `request_irq` functions are `serial21285_rx_chars` and `serial21285_tx_chars`. These functions will be called when an `RX` or `TX` interrupt occured. We will not dive in this part into details of these functions, because this chapter covers the interrupts and interrupts handling but not device and drivers. The next parameter - `flags` and as we can see, it is zero in both calls of the `request_irq` function. All acceptable flags are defined as `IRQF_*` macros in the [include/linux/interrupt.h](https://github.com/torvalds/linux/blob/master/include/linux/interrupt.h). Some of it:
+The [ISA](https://en.wikipedia.org/wiki/Industry_Standard_Architecture) IRQs on this board are from `0` to `15`, so, our interrupts will have first two numbers: `16` and `17`. Second parameters for two calls of the `request_irq` functions are `serial21285_rx_chars` and `serial21285_tx_chars`. These functions will be called when an `RX` or `TX` interrupt occurred. We will not dive in this part into details of these functions, because this chapter covers the interrupts and interrupts handling but not device and drivers. The next parameter - `flags` and as we can see, it is zero in both calls of the `request_irq` function. All acceptable flags are defined as `IRQF_*` macros in the [include/linux/interrupt.h](https://github.com/torvalds/linux/blob/master/include/linux/interrupt.h). Some of it:
 
 * `IRQF_SHARED` - allows sharing the irq among several devices;
 * `IRQF_PERCPU` - an interrupt is per cpu;

interrupts/interrupts-3.md

@@ -120,11 +120,11 @@ idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK
 
 Actually `debug` and `int3` are not interrupts handlers. Remember that before we can execute an interrupt/exception handler, we need to do some preparations as:
 
-* When an interrupt or exception occured, the processor uses an exception or interrupt vector as an index to a descriptor in the `IDT`;
+* When an interrupt or exception occurred, the processor uses an exception or interrupt vector as an index to a descriptor in the `IDT`;
 * In legacy mode `ss:esp` registers are pushed on the stack only if privilege level changed. In 64-bit mode `ss:rsp` pushed on the stack everytime;
 * During stack switching with `IST` the new `ss` selector is forced to null. Old `ss` and `rsp` are pushed on the new stack.
 * The `rflags`, `cs`, `rip` and error code pushed on the stack;
-* Control transfered to an interrupt handler;
+* Control transferred to an interrupt handler;
 * After an interrupt handler will finish its work and finishes with the `iret` instruction, old `ss` will be poped from the stack and loaded to the `ss` register.
 * `ss:rsp` will be popped from the stack unconditionally in the 64-bit mode and will be popped only if there is a privilege level change in legacy mode.
 * `iret` instruction will restore `rip`, `cs` and `rflags`;
@@ -443,7 +443,7 @@ That's all.
 Conclusion
 --------------------------------------------------------------------------------
 
-It is the end of the third part about interrupts and interrupt handling in the Linux kernel. We saw the initialization of the [Interrupt descriptor table](https://en.wikipedia.org/wiki/Interrupt_descriptor_table) in the previous part with the `#DB` and `#BP` gates and started to dive into preparation before control will be transfered to an exception handler and implementation of some interrupt handlers in this part. In the next part we will continue to dive into this theme and will go next by the `setup_arch` function and will try to understand interrupts handling related stuff.
+It is the end of the third part about interrupts and interrupt handling in the Linux kernel. We saw the initialization of the [Interrupt descriptor table](https://en.wikipedia.org/wiki/Interrupt_descriptor_table) in the previous part with the `#DB` and `#BP` gates and started to dive into preparation before control will be transferred to an exception handler and implementation of some interrupt handlers in this part. In the next part we will continue to dive into this theme and will go next by the `setup_arch` function and will try to understand interrupts handling related stuff.
 
 If you have any questions or suggestions write me a comment or ping me at [twitter](https://twitter.com/0xAX).
 

interrupts/interrupts-4.md

@@ -235,7 +235,7 @@ set_intr_gate(X86_TRAP_NM, device_not_available);
 Here we can see:
 
 * `#OF` or `Overflow` exception. This exception indicates that an overflow trap occurred when an special [INTO](http://x86.renejeschke.de/html/file_module_x86_id_142.html) instruction was executed;
-* `#BR` or `BOUND Range exceeded` exception. This exception indeicates that a `BOUND-range-exceed` fault occured when a [BOUND](http://pdos.csail.mit.edu/6.828/2005/readings/i386/BOUND.htm) instruction was executed;
+* `#BR` or `BOUND Range exceeded` exception. This exception indeicates that a `BOUND-range-exceed` fault occurred when a [BOUND](http://pdos.csail.mit.edu/6.828/2005/readings/i386/BOUND.htm) instruction was executed;
 * `#UD` or `Invalid Opcode` exception. Occurs when a processor attempted to execute invalid or reserved [opcode](https://en.wikipedia.org/?title=Opcode), processor attempted to execute instruction with invalid operand(s) and etc;
 * `#NM` or `Device Not Available` exception. Occurs when the processor tries to execute `x87 FPU` floating point instruction while `EM` flag in the [control register](https://en.wikipedia.org/wiki/Control_register#CR0) `cr0` was set.
 

interrupts/interrupts-7.md

@@ -14,14 +14,14 @@ Interrupts are signal that are sent across [IRQ](https://en.wikipedia.org/wiki/I
 
 I will try to describe all types of interrupts in this book.
 
-Generally, a handler of an `I/O` interrupt must be flexible enough to service several devices at the same time. For exmaple in the [PCI](https://en.wikipedia.org/wiki/Conventional_PCI) bus architecture several devices may share the same `IRQ` line. In the simplest way the Linux kernel must do following thing when an `I/O` interrupt occured:
+Generally, a handler of an `I/O` interrupt must be flexible enough to service several devices at the same time. For example in the [PCI](https://en.wikipedia.org/wiki/Conventional_PCI) bus architecture several devices may share the same `IRQ` line. In the simplest way the Linux kernel must do following thing when an `I/O` interrupt occurred:
 
 * Save the value of an `IRQ` and the register's contents on the kernel stack;
 * Send an acknowledgment to the hardware controller which is servicing the `IRQ` line;
 * Execute the interrupt service routine (next we will call it `ISR`) which is associated with the device;
 * Restore registers and return from an interrupt;
 
-Ok, we know a little theory and now let's start with the `early_irq_init` function. The implementation of the `early_irq_init` function is in the [kernel/irq/irqdesc.c](https://github.com/torvalds/linux/blob/master/kernel/irq/irqdesc.c). This function make early initialziation of the `irq_desc` structure. The `irq_desc` structure is the foundation of interrupt management code in the Linux kernel. An array of this structure, which has the same name - `irq_desc`, keeps track of every interrupt request source in the Linux kernel. This structure defined in the [include/linux/irqdesc.h](https://github.com/torvalds/linux/blob/master/include/linux/irqdesc.h) and as you can note it depends on the `CONFIG_SPARSE_IRQ` kernel configuration option. This kernel configuration option enables support for sparse irqs. The `irq_desc` structure contains many different fiels:
+Ok, we know a little theory and now let's start with the `early_irq_init` function. The implementation of the `early_irq_init` function is in the [kernel/irq/irqdesc.c](https://github.com/torvalds/linux/blob/master/kernel/irq/irqdesc.c). This function make early initialziation of the `irq_desc` structure. The `irq_desc` structure is the foundation of interrupt management code in the Linux kernel. An array of this structure, which has the same name - `irq_desc`, keeps track of every interrupt request source in the Linux kernel. This structure defined in the [include/linux/irqdesc.h](https://github.com/torvalds/linux/blob/master/include/linux/irqdesc.h) and as you can note it depends on the `CONFIG_SPARSE_IRQ` kernel configuration option. This kernel configuration option enables support for sparse irqs. The `irq_desc` structure contains many different files:
 
 * `irq_common_data` - per irq and chip data passed down to chip functions;
 * `status_use_accessors` - contains status of the interrupt source which is combination of the values from the `enum` from the [include/linux/irq.h](https://github.com/torvalds/linux/blob/master/include/linux/irq.h) and different macros which are defined in the same source code file;

interrupts/interrupts-8.md

@@ -6,7 +6,7 @@ Non-early initialization of the IRQs
 
 This is the eighth part of the Interrupts and Interrupt Handling in the Linux kernel [chapter](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-7.html) we started to dive into the external hardware [interrupts](https://en.wikipedia.org/wiki/Interrupt_request_%28PC_architecture%29). We looked on the implementation of the `early_irq_init` function from the [kernel/irq/irqdesc.c](https://github.com/torvalds/linux/blob/master/kernel/irq/irqdesc.c) source code file and saw the initialization of the `irq_desc` structure in this function. Remind that `irq_desc` structure (defined in the [include/linux/irqdesc.h](https://github.com/torvalds/linux/blob/master/include/linux/irqdesc.h#L46) is the foundation of interrupt management code in the Linux kernel and represents an interrupt descriptor. In this part we will continue to dive into the initialization stuff which is related to the external hardware interrupts.
 
-Right after the call of the `early_irq_init` function in the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c) we can see the call of the `init_IRQ` function. This function is architecture-specfic and defined in the [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c). The `init_IRQ` function makes initialization of the `vector_irq` [percpu](http://0xax.gitbooks.io/linux-insides/content/Concepts/per-cpu.html) variable that defined in the same [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c) source code file:
+Right after the call of the `early_irq_init` function in the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c) we can see the call of the `init_IRQ` function. This function is architecture-specific and defined in the [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c). The `init_IRQ` function makes initialization of the `vector_irq` [percpu](http://0xax.gitbooks.io/linux-insides/content/Concepts/per-cpu.html) variable that defined in the same [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c) source code file:
 
 ```C
 ...

interrupts/interrupts-9.md

@@ -466,7 +466,7 @@ The `queue_work` function just calls the `queue_work_on` function that queue wor
 __queue_work(cpu, wq, work);
 ```
 
-The `__queue_work` function gets the `work pool`. Yes, the `work pool` not `workqueue`. Actually, all `works` are not placed in the `workqueue`, but to the `work pool` that is represented by the `worker_pool` structure in the Linux kernel. As you can see above, the `workqueue_struct` structure has the `pwqs` field which is list of `worker_pools`. When we create a `workqueue`, it stands out for each processor the `pool_workqueue`. Each `pool_workqueue` associated with `worker_pool`, which is allocated on the same processor and corresponds to the type of priority queue. Through them `workqueue` interacts with `worker_pool`. So in the `__queue_work` function we set the cpu to the current processor with the `raw_smp_processor_id` (you can find information about this marco in the fouth [part](http://0xax.gitbooks.io/linux-insides/content/Initialization/linux-initialization-4.html) of the Linux kernel initialization process chapter), getting the `pool_workqueue` for the given `workqueue_struct` and insert the given `work` to the given `workqueue`:
+The `__queue_work` function gets the `work pool`. Yes, the `work pool` not `workqueue`. Actually, all `works` are not placed in the `workqueue`, but to the `work pool` that is represented by the `worker_pool` structure in the Linux kernel. As you can see above, the `workqueue_struct` structure has the `pwqs` field which is list of `worker_pools`. When we create a `workqueue`, it stands out for each processor the `pool_workqueue`. Each `pool_workqueue` associated with `worker_pool`, which is allocated on the same processor and corresponds to the type of priority queue. Through them `workqueue` interacts with `worker_pool`. So in the `__queue_work` function we set the cpu to the current processor with the `raw_smp_processor_id` (you can find information about this marco in the fourth [part](http://0xax.gitbooks.io/linux-insides/content/Initialization/linux-initialization-4.html) of the Linux kernel initialization process chapter), getting the `pool_workqueue` for the given `workqueue_struct` and insert the given `work` to the given `workqueue`:
 
 ```C
 static void __queue_work(int cpu, struct workqueue_struct *wq,