From: Paolo Bonzini <pbonzini@redhat.com>
To: Mike Day <ncmike@ncultra.org>
Cc: Paul Mckenney <paulmck@linux.vnet.ibm.com>,
Mathew Desnoyers <mathieu.desnoyers@efficios.com>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [Qemu-devel] [RFC PATCH] convert ram_list to RCU DQ
Date: Fri, 30 Aug 2013 10:19:16 +0200 [thread overview]
Message-ID: <52205584.5080509@redhat.com> (raw)
In-Reply-To: <CAGaKXu2vNT5zG5V1NOPQY5qT1=FLhEbVJq6mqVLRREN8QVz0Mg@mail.gmail.com>
Il 29/08/2013 21:18, Mike Day ha scritto:
>
>> Similarly, here the critical section includes the caller, and block is
>> living across calls to host. Again, for now just put all of ram_load
>> under a huge RCU critical section. Later we can use ram_list.version to
>> refresh the list and make the critical sections smaller.
>
> And: rcu_read_lock() and rcu_read_unlock() can be called recursively, so
> I can still leave the lock/unlock pair in host_from_stream_offset.
I'm not sure about that; returning an RCU-protected variable after
rcu_read_unlock() seems wrong to me because the pointer may not be valid
at that point. I suggest using a comment that asks to call
host_from_stream_offset within rcu_read_lock()/rcu_read_unlock().
However, if existing practice in the kernel is different, I'll bow to that.
Paolo
next prev parent reply other threads:[~2013-08-30 8:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-28 16:02 [Qemu-devel] [RFC PATCH] convert ram_list to RCU DQ Mike Day
2013-08-28 16:35 ` Paolo Bonzini
2013-08-29 19:18 ` Mike Day
2013-08-30 8:19 ` Paolo Bonzini [this message]
2013-08-30 14:08 ` Mike Day
2013-08-28 16:37 ` Paolo Bonzini
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