* list_head and lock?
@ 2013-11-18 1:19 韩磊
2013-11-18 1:48 ` anish singh
0 siblings, 1 reply; 3+ messages in thread
From: 韩磊 @ 2013-11-18 1:19 UTC (permalink / raw)
To: Linux Kernel Mailing List
when we delete,add,search,amend the list_head,should we use spinlock
or rcu in case of conflicit to list_head???
Thank you!
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: list_head and lock?
2013-11-18 1:19 list_head and lock? 韩磊
@ 2013-11-18 1:48 ` anish singh
2013-11-18 22:58 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: anish singh @ 2013-11-18 1:48 UTC (permalink / raw)
To: 韩磊; +Cc: Linux Kernel Mailing List
On Sun, Nov 17, 2013 at 5:19 PM, 韩磊 <bonben1989@gmail.com> wrote:
> when we delete,add,search,amend the list_head,should we use spinlock
> or rcu in case of conflicit to list_head???
There is no implicit locking when we use 'list' api's.You should explicitly
do that AFAIK.
>
> Thank you!
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: list_head and lock?
2013-11-18 1:48 ` anish singh
@ 2013-11-18 22:58 ` Paul E. McKenney
0 siblings, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2013-11-18 22:58 UTC (permalink / raw)
To: anish singh; +Cc: 韩磊, Linux Kernel Mailing List
On Sun, Nov 17, 2013 at 05:48:14PM -0800, anish singh wrote:
> On Sun, Nov 17, 2013 at 5:19 PM, 韩磊 <bonben1989@gmail.com> wrote:
> > when we delete,add,search,amend the list_head,should we use spinlock
> > or rcu in case of conflicit to list_head???
> There is no implicit locking when we use 'list' api's.You should explicitly
> do that AFAIK.
See Documentation/RCU/listRCU.txt for a summary of how to use RCU-protected
linked lists. But yes, readers need to explicitly do rcu_read_lock()
and rcu_read_unlock(), and updaters must coordinate with each others
somehow, for example, explicitly using spinlocks.
The list_head macros are about list manipulation and not so much about
synchronization.
Thanx, Paul
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