I am going through a book Linux Device Driver and I
find it very interesting and playing with the sample
device drivers. This is the best way to learn a device
driver concepts.
It always better to understand each example quoted by
Author as It may concepts clear.
I have a query regarding scull_follow function which
is being called and defined in main.c [ example
downloaded from Net].
/* Follow the list
*/
Scull_Dev *scull_follow(Scull_Dev *dev, int n)
{
printk("<1> The Scull_follow has been called \n");
printk("<1> The value of n is::%d\n",n);
while (n--) {
printk("The while Loop in Scull_follow has been
called \n");
if (!dev->next) {
printk("<1> The next data is NULL in
scull_follow \n");
dev->next = kmalloc(sizeof(Scull_Dev),
GFP_KERNEL);
memset(dev->next, 0, sizeof(Scull_Dev));
}
dev = dev->next;
continue;
}
return dev;
}
In this case, author has allocated a memory through
kmalloc for scull_devices and as per my understanding
kmalloc gives a block of contigous memory, so from
where this link list came into picture.
scull_devices = kmalloc(scull_nr_devs *
sizeof(Scull_Dev), GFP_KERNEL);
As per we are not intializing a *next data member of
the Scull_Dev structure.[Simith] Memsetting to 0 is initialising "next" to NULL.
Could any one clear my concepts as why we want
scull_follow?
Regards
Dinesh
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