In kernel, you can use semaphores, spin locks or any other synchronizing mechanism. Well right now I know only about semaphores and spin locks, so can tell you about that. If anybody else knows some other synchronizing mechanism in kernel, then please do mail about that. Semaphore: This is a heavy synchronizing mechanism and should be used if our critical section is big enough ...... this synchronizing mechanism puts the process to sleep on a semaphore specific waiting queue, if it is not able to acquire semaphore. Semaphore has mainly two elements, one is variable which tell if the semaphore is free or acquired, another is a queue of process sleeping/waiting for the semaphore to be released. In case your code is not able to acquire the semaphore, then the process under whose context you are executing the code will be put to sleep in the queue associated with semaphore. When a semaphore is released, all the process on waiting queue are waked up and then they again compete to acquire the semaphore, the process which schedules first get the semaphore and enters into critical section. Spin locks: This is a light weight synchronizing mechanism. In this processes are never put to sleep, rather they are put in a fast while loop to check the spin lock variable. As soon as the spin lock is released by other process, the process spinning on it gets the spin lock and enters in critical section. This is mainly used where the critical section is short. Read how to use these mechanisms: http://www.linuxjournal.com/modules.php?op=modload&name=NS-lj-issues/iss ue100&file=5833s1 In above explanations, when I say process, I mean control in kernel code running in process context. Cheers !! Gaurav -----Original Message----- From: Rakesh Jagota [mailto:j.rakesh@xxxxxxxxxxxxx] Sent: Thursday, September 30, 2004 9:35 PM To: Dhiman, Gaurav Cc: kernelnewbies@xxxxxxxxxxxx Subject: Re: Inter Module communication Hello Gaurav, Thanks for your prompt reply. Is there any inbuilt kernel mechanism like pipes etc.. to provide communication between to Modules(not two processes). I think if two modules are accessing the same data structure we need some sort of synchronization. what kind of synchronization shall i use . pls give a brief idea about it. Regards Rakesh ----- Original Message ----- From: "Dhiman, Gaurav" <Gaurav.Dhiman@xxxxxx> To: "Rakesh Jagota" <j.rakesh@xxxxxxxxxxxxx> Cc: <kernelnewbies@xxxxxxxxxxxx> Sent: Thursday, September 30, 2004 9:08 PM Subject: RE: Inter Module communication Your modules can make use of symbols (global variable and function names defined in module) exported by other modules. If you have two module and you want to make a communication between them, export few of the symbols of your modules so that they can be referred in your other modules and can make a communication thru it. Remember, symbols you exported will also be visible to all other modules, which might not be of yours, any other module can make use of it or can change it. Cheers !! Gaurav -----Original Message----- From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Rakesh Jagota Sent: Thursday, September 30, 2004 4:35 PM To: kernelnewbies@xxxxxxxxxxxx Subject: Inter Module communication Hi all, I have 2 modules and i would like to know any Inter module comm. mechanism is present in kernel modular programming. I know this is present at user level. -Pipe/messages Queues/fifos/shared memory. Thanks Rakesh -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
