how to send an event from kernel module to user space process

[raju82]

Hi all,
In my project i want to send an event from kernel module to user space process whenever the condition in the kernel module has satisfied. Presently i am using signals for this. But there are only two user defined signals SIGUSR1 , SIGUSR2 from this we can have only two conditions to be satisfied. suppose if i have more no. of conditions what i have to do. My query is Can i send an events from kernel module to user space and also what is the api for sending the events from kernel module to user space

[cbogdan]

Hi,

You know signals are used to notify a process of a particular event and provide an asynchronous form of notification. But in asynchronous I/O mechanism you have only one signal per process. If we have more descriptors for asynchronous I/O, we don't know which descriptor the signal corresponds to when the signal is delivered.

Instead, you can use polling mechanism, synchronous form of notification, (nonblocking I/O, wait for some event on a file descriptor) - poll(), select() (I/O multiplexing).

But you have to understand differences between synchronous and asynchronous techniques.