<< Previous Article In the last article, we discussed the usage of wait queues in Linux kernel. We saw the variants of wait_event(). Just for completeness, we will discuss how the wait queues are implemented internally. First step is the creation and initialization of wait queue entry. This is done as below: DEFINE_WAIT(wait_entry); Next step is to …
<< Previous Article The last article in this series focused on implementing the basic wait mechanism. It was a manual waiting where everything, starting from putting the process to the sleep to checking for the wake up event, was done by driver writer. But, such kind of manual waiting is error prone and may at times …
<< Previous Article In the last article, we managed to get our process blocked. As stated then, the code had couple of problems. One of them being unblocking the process. There was no one to wake our process up. Sleeping process is of no use. Another flaw was that our process was sleeping unconditionally. However, …
<< Previous Article Continuing our journey with Linux kernel internals, the next few articles in this series will focus on wait mechanisms in kernel. Now, you might be wondering, why do we need to wait in Linux driver? Well, there can be quite a lot of reasons to wait in driver. Let’s say you are …
<< Previous Article We have covered the various synchronization mechanisms in the previous articles. One of the thing common among them was that they put the process to sleep, if the lock is not available. Also, all those are prone to deadlock, if not implemented carefully. Sometimes however, we require to protect a simple variable …
<< Previous Article In the last two articles, we have discussed some of the commonly used synchronization mechanisms in kernel. It was observed that these synchronization mechanisms restrict the access to the resource, irrespective of the operation which thread/process wants to perform on the resource. This in turn, mean that even though one thread has …
In the previous article, we discussed about the basic synchronization mechanisms such as mutex and semaphores. As a part of that, there came up a couple of questions. If binary semaphore can achieve the synchronization as provided by mutex, then why do we need mutex at all? Another question was, can we use semaphore / …
In the previous article, we discussed about the kernel threads, wherein we discussed various aspects of threads such as creation, stopping, signalling and so on. Threads provide one of the ways to achieve multitasking in the kernel. While multitasking brings the definite improvement in the system performance, but it comes with its own side effects. …
In the previous article, we learned the basics of kernel threads such as creating the thread, running the thread and so on. In this article, we will dive a bit more into the kernel threads, where we will see the things such as stopping the thread, signalling the thread and so. So, let’s begin… Continuing …
In the previous article, we learned to write a simple kernel module. This was needed to kick start our journey into the Kernel Internals, as all of the code we are going to discuss, has to be pushed into the kernel as module. In this article, we will discuss about the Kernel Threads. So, lets …
