From mboxrd@z Thu Jan  1 00:00:00 1970
From: contemplatingzombie@gmail.com (contemplating zombie)
Date: Sat, 17 Dec 2011 19:15:30 -0500
Subject: Question about RCU
Message-ID: <CAO_gTC5ZGVoyMATX+ZSSHUpi9_knQ6xKdBDa94p7fwv2JrRcgA@mail.gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

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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