Commit a7455442 authored by Greg Banks's avatar Greg Banks Committed by Linus Torvalds
Browse files

[PATCH] knfsd: add svc_set_num_threads 



Currently knfsd keeps its own list of all nfsd threads in nfssvc.c; add a new
way of managing the list of all threads in a svc_serv.  Add
svc_create_pooled() to allow creation of a svc_serv whose threads are managed
by the sunrpc code.  Add svc_set_num_threads() to manage the number of threads
in a service, either per-pool or globally across the service.

Signed-off-by: default avatarGreg Banks <gnb@melbourne.sgi.com>
Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9a24ab57

include/linux/sunrpc/svc.h

+16 −5
Original line number Diff line number Diff line
@@ -17,6 +17,10 @@ 
#include <linux/wait.h>

#include <linux/mm.h>



/*

 * This is the RPC server thread function prototype

 */

typedef void		(*svc_thread_fn)(struct svc_rqst *);



/*

 *
@@ -34,6 +38,7 @@ struct svc_pool { 
	struct list_head	sp_threads;	/* idle server threads */

	struct list_head	sp_sockets;	/* pending sockets */

	unsigned int		sp_nrthreads;	/* # of threads in pool */

	struct list_head	sp_all_threads;	/* all server threads */

} ____cacheline_aligned_in_smp;



/*
@@ -68,6 +73,11 @@ struct svc_serv { 
						/* Callback to use when last thread

						 * exits.

						 */



	struct module *		sv_module;	/* optional module to count when

						 * adding threads */

	svc_thread_fn		sv_function;	/* main function for threads */

	int			sv_kill_signal;	/* signal to kill threads */

};



/*
@@ -164,6 +174,7 @@ static inline void svc_putu32(struct kvec *iov, __be32 val) 
 */

struct svc_rqst {

	struct list_head	rq_list;	/* idle list */

	struct list_head	rq_all;		/* all threads list */

	struct svc_sock *	rq_sock;	/* socket */

	struct sockaddr_in	rq_addr;	/* peer address */

	int			rq_addrlen;
@@ -218,6 +229,7 @@ struct svc_rqst { 
						 * to prevent encrypting page

						 * cache pages */

	wait_queue_head_t	rq_wait;	/* synchronization */

	struct task_struct	*rq_task;	/* service thread */

};



/*
@@ -358,11 +370,6 @@ struct svc_procedure { 
	unsigned int		pc_xdrressize;	/* maximum size of XDR reply */

};



/*

 * This is the RPC server thread function prototype

 */

typedef void		(*svc_thread_fn)(struct svc_rqst *);



/*

 * Function prototypes.

 */
@@ -370,6 +377,10 @@ struct svc_serv * svc_create(struct svc_program *, unsigned int, 
			      void (*shutdown)(struct svc_serv*));

int		   svc_create_thread(svc_thread_fn, struct svc_serv *);

void		   svc_exit_thread(struct svc_rqst *);

struct svc_serv *  svc_create_pooled(struct svc_program *, unsigned int,

			void (*shutdown)(struct svc_serv*),

			svc_thread_fn, int sig, struct module *);

int		   svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);

void		   svc_destroy(struct svc_serv *);

int		   svc_process(struct svc_rqst *);

int		   svc_register(struct svc_serv *, int, unsigned short);

net/sunrpc/sunrpc_syms.c

+2 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ EXPORT_SYMBOL(put_rpccred); 
/* RPC server stuff */

EXPORT_SYMBOL(svc_create);

EXPORT_SYMBOL(svc_create_thread);

EXPORT_SYMBOL(svc_create_pooled);

EXPORT_SYMBOL(svc_set_num_threads);

EXPORT_SYMBOL(svc_exit_thread);

EXPORT_SYMBOL(svc_destroy);

EXPORT_SYMBOL(svc_drop);

net/sunrpc/svc.c

+136 −3
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
#include <linux/net.h>

#include <linux/in.h>

#include <linux/mm.h>

#include <linux/interrupt.h>

#include <linux/module.h>



#include <linux/sunrpc/types.h>

#include <linux/sunrpc/xdr.h>
@@ -25,8 +27,8 @@ 
/*

 * Create an RPC service

 */

struct svc_serv *

svc_create(struct svc_program *prog, unsigned int bufsize,

static struct svc_serv *

__svc_create(struct svc_program *prog, unsigned int bufsize, int npools,

	   void (*shutdown)(struct svc_serv *serv))

{

	struct svc_serv	*serv;
@@ -61,7 +63,7 @@ svc_create(struct svc_program *prog, unsigned int bufsize, 
	init_timer(&serv->sv_temptimer);

	spin_lock_init(&serv->sv_lock);



	serv->sv_nrpools = 1;

	serv->sv_nrpools = npools;

	serv->sv_pools =

		kcalloc(sizeof(struct svc_pool), serv->sv_nrpools,

			GFP_KERNEL);
@@ -79,6 +81,7 @@ svc_create(struct svc_program *prog, unsigned int bufsize, 
		pool->sp_id = i;

		INIT_LIST_HEAD(&pool->sp_threads);

		INIT_LIST_HEAD(&pool->sp_sockets);

		INIT_LIST_HEAD(&pool->sp_all_threads);

		spin_lock_init(&pool->sp_lock);

	}
@@ -89,6 +92,31 @@ svc_create(struct svc_program *prog, unsigned int bufsize, 
	return serv;

}



struct svc_serv *

svc_create(struct svc_program *prog, unsigned int bufsize,

		void (*shutdown)(struct svc_serv *serv))

{

	return __svc_create(prog, bufsize, /*npools*/1, shutdown);

}



struct svc_serv *

svc_create_pooled(struct svc_program *prog, unsigned int bufsize,

		void (*shutdown)(struct svc_serv *serv),

		  svc_thread_fn func, int sig, struct module *mod)

{

	struct svc_serv *serv;



	serv = __svc_create(prog, bufsize, /*npools*/1, shutdown);



	if (serv != NULL) {

		serv->sv_function = func;

		serv->sv_kill_signal = sig;

		serv->sv_module = mod;

	}



	return serv;

}



/*

 * Destroy an RPC service.  Should be called with the BKL held

 */
@@ -203,6 +231,7 @@ __svc_create_thread(svc_thread_fn func, struct svc_serv *serv, 
	serv->sv_nrthreads++;

	spin_lock_bh(&pool->sp_lock);

	pool->sp_nrthreads++;

	list_add(&rqstp->rq_all, &pool->sp_all_threads);

	spin_unlock_bh(&pool->sp_lock);

	rqstp->rq_server = serv;

	rqstp->rq_pool = pool;
@@ -228,6 +257,109 @@ svc_create_thread(svc_thread_fn func, struct svc_serv *serv) 
	return __svc_create_thread(func, serv, &serv->sv_pools[0]);

}



/*

 * Choose a pool in which to create a new thread, for svc_set_num_threads

 */

static inline struct svc_pool *

choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)

{

	if (pool != NULL)

		return pool;



 	return &serv->sv_pools[(*state)++ % serv->sv_nrpools];

}



/*

 * Choose a thread to kill, for svc_set_num_threads

 */

static inline struct task_struct *

choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)

{

	unsigned int i;

	struct task_struct *task = NULL;



	if (pool != NULL) {

		spin_lock_bh(&pool->sp_lock);

	} else {

		/* choose a pool in round-robin fashion */

 		for (i = 0; i < serv->sv_nrpools; i++) {

 			pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];

			spin_lock_bh(&pool->sp_lock);

 			if (!list_empty(&pool->sp_all_threads))

 				goto found_pool;

			spin_unlock_bh(&pool->sp_lock);

 		}

		return NULL;

	}



found_pool:

	if (!list_empty(&pool->sp_all_threads)) {

		struct svc_rqst *rqstp;



		/*

		 * Remove from the pool->sp_all_threads list

		 * so we don't try to kill it again.

		 */

		rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);

		list_del_init(&rqstp->rq_all);

		task = rqstp->rq_task;

    	}

	spin_unlock_bh(&pool->sp_lock);



	return task;

}



/*

 * Create or destroy enough new threads to make the number

 * of threads the given number.  If `pool' is non-NULL, applies

 * only to threads in that pool, otherwise round-robins between

 * all pools.  Must be called with a svc_get() reference and

 * the BKL held.

 *

 * Destroying threads relies on the service threads filling in

 * rqstp->rq_task, which only the nfs ones do.  Assumes the serv

 * has been created using svc_create_pooled().

 *

 * Based on code that used to be in nfsd_svc() but tweaked

 * to be pool-aware.

 */

int

svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)

{

	struct task_struct *victim;

	int error = 0;

	unsigned int state = serv->sv_nrthreads-1;



	if (pool == NULL) {

		/* The -1 assumes caller has done a svc_get() */

		nrservs -= (serv->sv_nrthreads-1);

	} else {

		spin_lock_bh(&pool->sp_lock);

		nrservs -= pool->sp_nrthreads;

		spin_unlock_bh(&pool->sp_lock);

	}



	/* create new threads */

	while (nrservs > 0) {

		nrservs--;

		__module_get(serv->sv_module);

		error = __svc_create_thread(serv->sv_function, serv,

					    choose_pool(serv, pool, &state));

		if (error < 0) {

			module_put(serv->sv_module);

			break;

		}

	}

	/* destroy old threads */

	while (nrservs < 0 &&

	       (victim = choose_victim(serv, pool, &state)) != NULL) {

		send_sig(serv->sv_kill_signal, victim, 1);

		nrservs++;

	}



	return error;

}



/*

 * Called from a server thread as it's exiting.  Caller must hold BKL.

 */
@@ -244,6 +376,7 @@ svc_exit_thread(struct svc_rqst *rqstp) 


	spin_lock_bh(&pool->sp_lock);

	pool->sp_nrthreads--;

	list_del(&rqstp->rq_all);

	spin_unlock_bh(&pool->sp_lock);



	kfree(rqstp);

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