Re: [lustre-devel] [PATCH 19/19] staging: lustre: remove l_wait_event() and related code

[Patrick Farrell <paf@cray.com>]

With the fix from yesterday, these look good.  Thanks, Neil.

Reviewed-by: Patrick Farrell <paf@cray.com>

- Patrick

On 2/12/18, 5:52 PM, "lustre-devel on behalf of NeilBrown" <lustre-devel-bounces@lists.lustre.org on behalf of neilb@suse.com> wrote:

    These macros are no longer used, so they can
    be removed.
    
    Reviewed-by: James Simmons <jsimmons@infradead.org>
    Signed-off-by: NeilBrown <neilb@suse.com>
    ---
     drivers/staging/lustre/lustre/include/lustre_lib.h |  249 --------------------
     1 file changed, 249 deletions(-)
    
    diff --git a/drivers/staging/lustre/lustre/include/lustre_lib.h b/drivers/staging/lustre/lustre/include/lustre_lib.h
    index ccc1a329e42b..1efd86f18c1f 100644
    --- a/drivers/staging/lustre/lustre/include/lustre_lib.h
    +++ b/drivers/staging/lustre/lustre/include/lustre_lib.h
    @@ -76,123 +76,6 @@ int do_set_info_async(struct obd_import *imp,
     
     void target_send_reply(struct ptlrpc_request *req, int rc, int fail_id);
     
    -/*
    - * l_wait_event is a flexible sleeping function, permitting simple caller
    - * configuration of interrupt and timeout sensitivity along with actions to
    - * be performed in the event of either exception.
    - *
    - * The first form of usage looks like this:
    - *
    - * struct l_wait_info lwi = LWI_TIMEOUT_INTR(timeout, timeout_handler,
    - *					   intr_handler, callback_data);
    - * rc = l_wait_event(waitq, condition, &lwi);
    - *
    - * l_wait_event() makes the current process wait on 'waitq' until 'condition'
    - * is TRUE or a "killable" signal (SIGTERM, SIKGILL, SIGINT) is pending.  It
    - * returns 0 to signify 'condition' is TRUE, but if a signal wakes it before
    - * 'condition' becomes true, it optionally calls the specified 'intr_handler'
    - * if not NULL, and returns -EINTR.
    - *
    - * If a non-zero timeout is specified, signals are ignored until the timeout
    - * has expired.  At this time, if 'timeout_handler' is not NULL it is called.
    - * If it returns FALSE l_wait_event() continues to wait as described above with
    - * signals enabled.  Otherwise it returns -ETIMEDOUT.
    - *
    - * LWI_INTR(intr_handler, callback_data) is shorthand for
    - * LWI_TIMEOUT_INTR(0, NULL, intr_handler, callback_data)
    - *
    - * The second form of usage looks like this:
    - *
    - * struct l_wait_info lwi = LWI_TIMEOUT(timeout, timeout_handler);
    - * rc = l_wait_event(waitq, condition, &lwi);
    - *
    - * This form is the same as the first except that it COMPLETELY IGNORES
    - * SIGNALS.  The caller must therefore beware that if 'timeout' is zero, or if
    - * 'timeout_handler' is not NULL and returns FALSE, then the ONLY thing that
    - * can unblock the current process is 'condition' becoming TRUE.
    - *
    - * Another form of usage is:
    - * struct l_wait_info lwi = LWI_TIMEOUT_INTERVAL(timeout, interval,
    - *					       timeout_handler);
    - * rc = l_wait_event(waitq, condition, &lwi);
    - * This is the same as previous case, but condition is checked once every
    - * 'interval' jiffies (if non-zero).
    - *
    - * Subtle synchronization point: this macro does *not* necessary takes
    - * wait-queue spin-lock before returning, and, hence, following idiom is safe
    - * ONLY when caller provides some external locking:
    - *
    - *	     Thread1			    Thread2
    - *
    - *   l_wait_event(&obj->wq, ....);				       (1)
    - *
    - *				    wake_up(&obj->wq):		 (2)
    - *					 spin_lock(&q->lock);	  (2.1)
    - *					 __wake_up_common(q, ...);     (2.2)
    - *					 spin_unlock(&q->lock, flags); (2.3)
    - *
    - *   kfree(obj);						  (3)
    - *
    - * As l_wait_event() may "short-cut" execution and return without taking
    - * wait-queue spin-lock, some additional synchronization is necessary to
    - * guarantee that step (3) can begin only after (2.3) finishes.
    - *
    - * XXX nikita: some ptlrpc daemon threads have races of that sort.
    - *
    - */
    -
    -#define LWI_ON_SIGNAL_NOOP ((void (*)(void *))(-1))
    -
    -struct l_wait_info {
    -	long lwi_timeout;
    -	long lwi_interval;
    -	int	    lwi_allow_intr;
    -	int  (*lwi_on_timeout)(void *);
    -	void (*lwi_on_signal)(void *);
    -	void  *lwi_cb_data;
    -};
    -
    -/* NB: LWI_TIMEOUT ignores signals completely */
    -#define LWI_TIMEOUT(time, cb, data)	     \
    -((struct l_wait_info) {			 \
    -	.lwi_timeout    = time,		 \
    -	.lwi_on_timeout = cb,		   \
    -	.lwi_cb_data    = data,		 \
    -	.lwi_interval   = 0,		    \
    -	.lwi_allow_intr = 0		     \
    -})
    -
    -#define LWI_TIMEOUT_INTERVAL(time, interval, cb, data)  \
    -((struct l_wait_info) {				 \
    -	.lwi_timeout    = time,			 \
    -	.lwi_on_timeout = cb,			   \
    -	.lwi_cb_data    = data,			 \
    -	.lwi_interval   = interval,		     \
    -	.lwi_allow_intr = 0			     \
    -})
    -
    -#define LWI_TIMEOUT_INTR(time, time_cb, sig_cb, data)   \
    -((struct l_wait_info) {				 \
    -	.lwi_timeout    = time,			 \
    -	.lwi_on_timeout = time_cb,		      \
    -	.lwi_on_signal  = sig_cb,		       \
    -	.lwi_cb_data    = data,			 \
    -	.lwi_interval   = 0,			    \
    -	.lwi_allow_intr = 0			     \
    -})
    -
    -#define LWI_TIMEOUT_INTR_ALL(time, time_cb, sig_cb, data)       \
    -((struct l_wait_info) {					 \
    -	.lwi_timeout    = time,				 \
    -	.lwi_on_timeout = time_cb,			      \
    -	.lwi_on_signal  = sig_cb,			       \
    -	.lwi_cb_data    = data,				 \
    -	.lwi_interval   = 0,				    \
    -	.lwi_allow_intr = 1				     \
    -})
    -
    -#define LWI_INTR(cb, data)  LWI_TIMEOUT_INTR(0, NULL, cb, data)
    -
     #define LUSTRE_FATAL_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) |		\
     			   sigmask(SIGTERM) | sigmask(SIGQUIT) |	\
     			   sigmask(SIGALRM))
    @@ -201,138 +84,6 @@ static inline int l_fatal_signal_pending(struct task_struct *p)
     	return signal_pending(p) && sigtestsetmask(&p->pending.signal, LUSTRE_FATAL_SIGS);
     }
     
    -/**
    - * wait_queue_entry_t of Linux (version < 2.6.34) is a FIFO list for exclusively
    - * waiting threads, which is not always desirable because all threads will
    - * be waken up again and again, even user only needs a few of them to be
    - * active most time. This is not good for performance because cache can
    - * be polluted by different threads.
    - *
    - * LIFO list can resolve this problem because we always wakeup the most
    - * recent active thread by default.
    - *
    - * NB: please don't call non-exclusive & exclusive wait on the same
    - * waitq if add_wait_queue_exclusive_head is used.
    - */
    -#define add_wait_queue_exclusive_head(waitq, link)		\
    -{								\
    -	unsigned long flags;					\
    -								\
    -	spin_lock_irqsave(&((waitq)->lock), flags);		\
    -	__add_wait_queue_exclusive(waitq, link);		\
    -	spin_unlock_irqrestore(&((waitq)->lock), flags);	\
    -}
    -
    -/*
    - * wait for @condition to become true, but no longer than timeout, specified
    - * by @info.
    - */
    -#define __l_wait_event(wq, condition, info, ret, l_add_wait)		   \
    -do {									   \
    -	wait_queue_entry_t __wait;						 \
    -	long __timeout = info->lwi_timeout;			  \
    -	sigset_t   __blocked;					      \
    -	int   __allow_intr = info->lwi_allow_intr;			     \
    -									       \
    -	ret = 0;							       \
    -	if (condition)							 \
    -		break;							 \
    -									       \
    -	init_waitqueue_entry(&__wait, current);					    \
    -	l_add_wait(&wq, &__wait);					      \
    -									       \
    -	/* Block all signals (just the non-fatal ones if no timeout). */       \
    -	if (info->lwi_on_signal && (__timeout == 0 || __allow_intr))   \
    -		__blocked = cfs_block_sigsinv(LUSTRE_FATAL_SIGS);	      \
    -	else								   \
    -		__blocked = cfs_block_sigsinv(0);			      \
    -									       \
    -	for (;;) {							     \
    -		if (condition)						 \
    -			break;						 \
    -									       \
    -		set_current_state(TASK_INTERRUPTIBLE);			       \
    -									       \
    -		if (__timeout == 0) {					  \
    -			schedule();					       \
    -		} else {						       \
    -			long interval = info->lwi_interval ?	  \
    -					     min_t(long,	     \
    -						 info->lwi_interval, __timeout) : \
    -					     __timeout;			\
    -			long remaining = schedule_timeout(interval);\
    -			__timeout = cfs_time_sub(__timeout,		    \
    -					    cfs_time_sub(interval, remaining));\
    -			if (__timeout == 0) {				  \
    -				if (!info->lwi_on_timeout ||		      \
    -				    info->lwi_on_timeout(info->lwi_cb_data)) { \
    -					ret = -ETIMEDOUT;		      \
    -					break;				 \
    -				}					      \
    -				/* Take signals after the timeout expires. */  \
    -				if (info->lwi_on_signal)		       \
    -				    (void)cfs_block_sigsinv(LUSTRE_FATAL_SIGS);\
    -			}						      \
    -		}							      \
    -									       \
    -		set_current_state(TASK_RUNNING);			       \
    -									       \
    -		if (condition)						 \
    -			break;						 \
    -		if (signal_pending(current)) {				    \
    -			if (info->lwi_on_signal &&		     \
    -			    (__timeout == 0 || __allow_intr)) {		\
    -				if (info->lwi_on_signal != LWI_ON_SIGNAL_NOOP) \
    -					info->lwi_on_signal(info->lwi_cb_data);\
    -				ret = -EINTR;				  \
    -				break;					 \
    -			}						      \
    -			/* We have to do this here because some signals */     \
    -			/* are not blockable - ie from strace(1).       */     \
    -			/* In these cases we want to schedule_timeout() */     \
    -			/* again, because we don't want that to return  */     \
    -			/* -EINTR when the RPC actually succeeded.      */     \
    -			/* the recalc_sigpending() below will deliver the */     \
    -			/* signal properly.			     */     \
    -			cfs_clear_sigpending();				\
    -		}							      \
    -	}								      \
    -									       \
    -	cfs_restore_sigs(__blocked);					   \
    -									       \
    -	remove_wait_queue(&wq, &__wait);					   \
    -} while (0)
    -
    -#define l_wait_event(wq, condition, info)		       \
    -({							      \
    -	int		 __ret;			      \
    -	struct l_wait_info *__info = (info);		    \
    -								\
    -	__l_wait_event(wq, condition, __info,		   \
    -		       __ret, add_wait_queue);		   \
    -	__ret;						  \
    -})
    -
    -#define l_wait_event_exclusive(wq, condition, info)	     \
    -({							      \
    -	int		 __ret;			      \
    -	struct l_wait_info *__info = (info);		    \
    -								\
    -	__l_wait_event(wq, condition, __info,		   \
    -		       __ret, add_wait_queue_exclusive);	 \
    -	__ret;						  \
    -})
    -
    -#define l_wait_event_exclusive_head(wq, condition, info)	\
    -({							      \
    -	int		 __ret;			      \
    -	struct l_wait_info *__info = (info);		    \
    -								\
    -	__l_wait_event(wq, condition, __info,		   \
    -		       __ret, add_wait_queue_exclusive_head);    \
    -	__ret;						  \
    -})
    -
     /** @} lib */
     
     
    
    
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