Re: rcu read-side protection

[Paul E. McKenney]

On Tue, Aug 16, 2005 at 05:09:29PM -0700, Suzanne Wood wrote:
[ . . . ]
> A read-side critical section is marked to protect the dereference of the 
> dn_ptr and assignment to dn_db which is a pointer to a dn_dev.  (struct 
> net_device is defined in /linux/netdevice.h and its dn_ptr in 
> /include/net/dn_dev.h)  Should this rcu-protection be extended to the line 
> following rcu_read_lock()?  Even though use_long is a simple char, it 
> appears to be a member of an rcu-protected structure.

Looks to me that this could indeed be a problem -- the structure
pointed to by dn_db could potentially be freed immediately after the
rcu_read_unlock(), unless there is some other non-obvious locking
mechanism protecting it.  In which case, why the rcu_read_lock()
and rcu_read_unlock()...

						Thanx, Paul
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