* a strange lock
@ 2020-02-03 12:31 Frank Huang
2020-02-03 13:30 ` Leon Romanovsky
0 siblings, 1 reply; 2+ messages in thread
From: Frank Huang @ 2020-02-03 12:31 UTC (permalink / raw)
To: linux-rdma
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/infiniband/core/cma.c#n1832
/*
* Wait for any active callback to finish. New callbacks will find
* the id_priv state set to destroying and abort.
*/
mutex_lock(&id_priv->handler_mutex);
mutex_unlock(&id_priv->handler_mutex);
It does nothing between the lock, what 's the meaning of it?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: a strange lock
2020-02-03 12:31 a strange lock Frank Huang
@ 2020-02-03 13:30 ` Leon Romanovsky
0 siblings, 0 replies; 2+ messages in thread
From: Leon Romanovsky @ 2020-02-03 13:30 UTC (permalink / raw)
To: Frank Huang; +Cc: linux-rdma
On Mon, Feb 03, 2020 at 08:31:10PM +0800, Frank Huang wrote:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/infiniband/core/cma.c#n1832
>
> /*
> * Wait for any active callback to finish. New callbacks will find
> * the id_priv state set to destroying and abort.
> */
> mutex_lock(&id_priv->handler_mutex);
> mutex_unlock(&id_priv->handler_mutex);
>
> It does nothing between the lock, what 's the meaning of it?
It is a way to implement wait_for_completion paradigm, by ensuring
that all cm_id works or will see RDMA_CM_DESTROYING state (they need
to take handler_mutex, before every call to cma_exch), or will
complete their execution and release handler_mutex.
Thanks
^ permalink raw reply [flat|nested] 2+ messages in thread
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