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Question: How to call a function in user space from inside the kernel ?

Forum: The Linux Kernel Hackers' Guide
Date: Thu, 02 Apr 1998 16:03:21 GMT
From: Ronald Tonn <>

Is there a way to call a function inside an application from a device driver (in kernel mode)?

I've come across this problem while working on an my ATM network driver. When opening a channel the ATM application calls the driver with a pointer to a receive function that should be called whenever data is received on that channel.

If I use this pointer (which points into user space) inside the driver as shown below the whole systems crashes appearently because I'm trying to execute a user program in kernel mode.

	receive_ptr(buffer, buffer_size);

Does anyone know how to fix this problem?