Question about RCU

Question about RCU

[contemplating zombie]

Hi,

I understand that multiple readers have to use rcu_read_lock(void) and
rcu_read_unlock(void) to read data protected by rcu. However, I do not
understand how the kernel distinguishes between multiple rcu protected
regions.

For e.g. if a region/data is protected by a mutex or spinlock, then the
code is something like:

int data;
mutex_t/spinlock_t lock;

print_data()
{
acquire(lock);
release(lock);
}

Here kernel can distinguish between different regions/data using different
locks used to protect it. However, the rcu_read(un)lock() do not accept any
lock as a parameter.
How does it manage under the hood?

-Thanks.
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Question about RCU

[Jonathan Neuschäfer]

On Sat, Dec 17, 2011 at 07:15:30PM -0500, contemplating zombie wrote:
> Hi,
> 
> I understand that multiple readers have to use rcu_read_lock(void) and
> rcu_read_unlock(void) to read data protected by rcu. However, I do not
> understand how the kernel distinguishes between multiple rcu protected
> regions.

It doesn't.
Have you read Documentation/RCU/whatisRCU.txt?

Thanks,
Jonathan Neusch?fer