linux-kernel - Re: [PATCH 07/19] staging: lustre: simplify l_wait

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Date:   Wed, 17 Jan 2018 15:29:52 +0000 (GMT)
From:   James Simmons <jsimmons@...radead.org>
To:     NeilBrown <neilb@...e.com>
cc:     Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        lkml <linux-kernel@...r.kernel.org>,
        lustre <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 07/19] staging: lustre: simplify l_wait_event when intr
 handler but no timeout.


> If l_wait_event() is given a function to be called on a signal,
> but no timeout or timeout handler, then the intr function is simply
> called at the end if the wait was aborted by a signal.
> So a simpler way to write the code (in the one place this case is
> used) it to open-code the body of the function after the
> wait_event, if -ERESTARTSYS was returned.

Reviewed-by: James Simmons <jsimmons@...radead.org>
 
> Signed-off-by: NeilBrown <neilb@...e.com>
> ---
>  drivers/staging/lustre/lustre/ldlm/ldlm_flock.c |   30 +++++------------------
>  1 file changed, 7 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
> index 657ab95091a0..411b540b96d9 100644
> --- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
> +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
> @@ -310,24 +310,6 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req)
>  	return LDLM_ITER_CONTINUE;
>  }
>  
> -struct ldlm_flock_wait_data {
> -	struct ldlm_lock *fwd_lock;
> -};
> -
> -static void
> -ldlm_flock_interrupted_wait(void *data)
> -{
> -	struct ldlm_lock *lock;
> -
> -	lock = ((struct ldlm_flock_wait_data *)data)->fwd_lock;
> -
> -	lock_res_and_lock(lock);
> -
> -	/* client side - set flag to prevent lock from being put on LRU list */
> -	ldlm_set_cbpending(lock);
> -	unlock_res_and_lock(lock);
> -}
> -
>  /**
>   * Flock completion callback function.
>   *
> @@ -342,8 +324,6 @@ int
>  ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
>  {
>  	struct file_lock		*getlk = lock->l_ast_data;
> -	struct ldlm_flock_wait_data	fwd;
> -	struct l_wait_info		lwi;
>  	int				rc = 0;
>  
>  	OBD_FAIL_TIMEOUT(OBD_FAIL_LDLM_CP_CB_WAIT2, 4);
> @@ -372,13 +352,17 @@ ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
>  
>  	LDLM_DEBUG(lock,
>  		   "client-side enqueue returned a blocked lock, sleeping");
> -	fwd.fwd_lock = lock;
> -	lwi = LWI_TIMEOUT_INTR(0, NULL, ldlm_flock_interrupted_wait, &fwd);
>  
>  	/* Go to sleep until the lock is granted. */
> -	rc = l_wait_event(lock->l_waitq, is_granted_or_cancelled(lock), &lwi);
> +	rc = l_wait_event_abortable(lock->l_waitq, is_granted_or_cancelled(lock));
>  
>  	if (rc) {
> +		lock_res_and_lock(lock);
> +
> +		/* client side - set flag to prevent lock from being put on LRU list */
> +		ldlm_set_cbpending(lock);
> +		unlock_res_and_lock(lock);
> +
>  		LDLM_DEBUG(lock, "client-side enqueue waking up: failed (%d)",
>  			   rc);
>  		return rc;
> 
> 
>