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7c4310ff56
The rpciod workqueue is on the write-out path for freeing dirty memory, so it is important that it never block waiting for memory to be allocated - this can lead to a deadlock. rpc_execute() - which is often called by an rpciod work item - calls rcp_task_release_client() which can lead to rpc_free_client(). rpc_free_client() makes two calls which could potentially block wating for memory allocation. rpc_clnt_debugfs_unregister() calls into debugfs and will block while any of the debugfs files are being accessed. In particular it can block while any of the 'open' methods are being called and all of these use malloc for one thing or another. So this can deadlock if the memory allocation waits for NFS to complete some writes via rpciod. rpc_clnt_remove_pipedir() can take the inode_lock() and while it isn't obvious that memory allocations can happen while the lock it held, it is safer to assume they might and to not let rpciod call rpc_clnt_remove_pipedir(). So this patch moves these two calls (together with the final kfree() and rpciod_down()) into a work-item to be run from the system work-queue. rpciod can continue its important work, and the final stages of the free can happen whenever they happen. I have seen this deadlock on a 4.12 based kernel where debugfs used synchronize_srcu() when removing objects. synchronize_srcu() requires a workqueue and there were no free workther threads and none could be allocated. While debugsfs no longer uses SRCU, I believe the deadlock is still possible. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
245 lines
7.9 KiB
C
245 lines
7.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* linux/include/linux/sunrpc/clnt.h
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*
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* Declarations for the high-level RPC client interface
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*
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* Copyright (C) 1995, 1996, Olaf Kirch <okir@monad.swb.de>
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*/
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#ifndef _LINUX_SUNRPC_CLNT_H
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#define _LINUX_SUNRPC_CLNT_H
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/sunrpc/msg_prot.h>
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#include <linux/sunrpc/sched.h>
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#include <linux/sunrpc/xprt.h>
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#include <linux/sunrpc/auth.h>
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#include <linux/sunrpc/stats.h>
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#include <linux/sunrpc/xdr.h>
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#include <linux/sunrpc/timer.h>
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#include <linux/sunrpc/rpc_pipe_fs.h>
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#include <asm/signal.h>
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#include <linux/path.h>
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#include <net/ipv6.h>
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#include <linux/sunrpc/xprtmultipath.h>
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struct rpc_inode;
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/*
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* The high-level client handle
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*/
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struct rpc_clnt {
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atomic_t cl_count; /* Number of references */
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unsigned int cl_clid; /* client id */
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struct list_head cl_clients; /* Global list of clients */
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struct list_head cl_tasks; /* List of tasks */
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spinlock_t cl_lock; /* spinlock */
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struct rpc_xprt __rcu * cl_xprt; /* transport */
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const struct rpc_procinfo *cl_procinfo; /* procedure info */
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u32 cl_prog, /* RPC program number */
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cl_vers, /* RPC version number */
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cl_maxproc; /* max procedure number */
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struct rpc_auth * cl_auth; /* authenticator */
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struct rpc_stat * cl_stats; /* per-program statistics */
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struct rpc_iostats * cl_metrics; /* per-client statistics */
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unsigned int cl_softrtry : 1,/* soft timeouts */
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cl_softerr : 1,/* Timeouts return errors */
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cl_discrtry : 1,/* disconnect before retry */
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cl_noretranstimeo: 1,/* No retransmit timeouts */
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cl_autobind : 1,/* use getport() */
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cl_chatty : 1;/* be verbose */
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struct rpc_rtt * cl_rtt; /* RTO estimator data */
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const struct rpc_timeout *cl_timeout; /* Timeout strategy */
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atomic_t cl_swapper; /* swapfile count */
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int cl_nodelen; /* nodename length */
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char cl_nodename[UNX_MAXNODENAME+1];
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struct rpc_pipe_dir_head cl_pipedir_objects;
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struct rpc_clnt * cl_parent; /* Points to parent of clones */
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struct rpc_rtt cl_rtt_default;
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struct rpc_timeout cl_timeout_default;
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const struct rpc_program *cl_program;
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const char * cl_principal; /* use for machine cred */
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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struct dentry *cl_debugfs; /* debugfs directory */
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#endif
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/* cl_work is only needed after cl_xpi is no longer used,
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* and that are of similar size
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*/
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union {
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struct rpc_xprt_iter cl_xpi;
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struct work_struct cl_work;
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};
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const struct cred *cl_cred;
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};
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/*
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* General RPC program info
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*/
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#define RPC_MAXVERSION 4
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struct rpc_program {
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const char * name; /* protocol name */
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u32 number; /* program number */
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unsigned int nrvers; /* number of versions */
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const struct rpc_version ** version; /* version array */
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struct rpc_stat * stats; /* statistics */
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const char * pipe_dir_name; /* path to rpc_pipefs dir */
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};
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struct rpc_version {
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u32 number; /* version number */
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unsigned int nrprocs; /* number of procs */
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const struct rpc_procinfo *procs; /* procedure array */
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unsigned int *counts; /* call counts */
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};
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/*
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* Procedure information
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*/
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struct rpc_procinfo {
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u32 p_proc; /* RPC procedure number */
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kxdreproc_t p_encode; /* XDR encode function */
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kxdrdproc_t p_decode; /* XDR decode function */
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unsigned int p_arglen; /* argument hdr length (u32) */
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unsigned int p_replen; /* reply hdr length (u32) */
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unsigned int p_timer; /* Which RTT timer to use */
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u32 p_statidx; /* Which procedure to account */
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const char * p_name; /* name of procedure */
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};
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struct rpc_create_args {
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struct net *net;
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int protocol;
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struct sockaddr *address;
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size_t addrsize;
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struct sockaddr *saddress;
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const struct rpc_timeout *timeout;
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const char *servername;
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const char *nodename;
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const struct rpc_program *program;
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u32 prognumber; /* overrides program->number */
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u32 version;
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rpc_authflavor_t authflavor;
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u32 nconnect;
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unsigned long flags;
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char *client_name;
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struct svc_xprt *bc_xprt; /* NFSv4.1 backchannel */
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const struct cred *cred;
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};
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struct rpc_add_xprt_test {
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void (*add_xprt_test)(struct rpc_clnt *clnt,
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struct rpc_xprt *xprt,
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void *calldata);
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void *data;
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};
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/* Values for "flags" field */
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#define RPC_CLNT_CREATE_HARDRTRY (1UL << 0)
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#define RPC_CLNT_CREATE_AUTOBIND (1UL << 2)
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#define RPC_CLNT_CREATE_NONPRIVPORT (1UL << 3)
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#define RPC_CLNT_CREATE_NOPING (1UL << 4)
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#define RPC_CLNT_CREATE_DISCRTRY (1UL << 5)
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#define RPC_CLNT_CREATE_QUIET (1UL << 6)
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#define RPC_CLNT_CREATE_INFINITE_SLOTS (1UL << 7)
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#define RPC_CLNT_CREATE_NO_IDLE_TIMEOUT (1UL << 8)
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#define RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT (1UL << 9)
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#define RPC_CLNT_CREATE_SOFTERR (1UL << 10)
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#define RPC_CLNT_CREATE_REUSEPORT (1UL << 11)
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struct rpc_clnt *rpc_create(struct rpc_create_args *args);
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struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *,
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const struct rpc_program *, u32);
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struct rpc_clnt *rpc_clone_client(struct rpc_clnt *);
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struct rpc_clnt *rpc_clone_client_set_auth(struct rpc_clnt *,
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rpc_authflavor_t);
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int rpc_switch_client_transport(struct rpc_clnt *,
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struct xprt_create *,
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const struct rpc_timeout *);
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void rpc_shutdown_client(struct rpc_clnt *);
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void rpc_release_client(struct rpc_clnt *);
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void rpc_task_release_transport(struct rpc_task *);
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void rpc_task_release_client(struct rpc_task *);
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struct rpc_xprt *rpc_task_get_xprt(struct rpc_clnt *clnt,
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struct rpc_xprt *xprt);
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int rpcb_create_local(struct net *);
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void rpcb_put_local(struct net *);
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int rpcb_register(struct net *, u32, u32, int, unsigned short);
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int rpcb_v4_register(struct net *net, const u32 program,
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const u32 version,
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const struct sockaddr *address,
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const char *netid);
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void rpcb_getport_async(struct rpc_task *);
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void rpc_prepare_reply_pages(struct rpc_rqst *req, struct page **pages,
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unsigned int base, unsigned int len,
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unsigned int hdrsize);
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void rpc_call_start(struct rpc_task *);
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int rpc_call_async(struct rpc_clnt *clnt,
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const struct rpc_message *msg, int flags,
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const struct rpc_call_ops *tk_ops,
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void *calldata);
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int rpc_call_sync(struct rpc_clnt *clnt,
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const struct rpc_message *msg, int flags);
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struct rpc_task *rpc_call_null(struct rpc_clnt *clnt, struct rpc_cred *cred,
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int flags);
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int rpc_restart_call_prepare(struct rpc_task *);
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int rpc_restart_call(struct rpc_task *);
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void rpc_setbufsize(struct rpc_clnt *, unsigned int, unsigned int);
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struct net * rpc_net_ns(struct rpc_clnt *);
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size_t rpc_max_payload(struct rpc_clnt *);
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size_t rpc_max_bc_payload(struct rpc_clnt *);
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unsigned int rpc_num_bc_slots(struct rpc_clnt *);
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void rpc_force_rebind(struct rpc_clnt *);
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size_t rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t);
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const char *rpc_peeraddr2str(struct rpc_clnt *, enum rpc_display_format_t);
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int rpc_localaddr(struct rpc_clnt *, struct sockaddr *, size_t);
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int rpc_clnt_iterate_for_each_xprt(struct rpc_clnt *clnt,
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int (*fn)(struct rpc_clnt *, struct rpc_xprt *, void *),
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void *data);
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int rpc_clnt_test_and_add_xprt(struct rpc_clnt *clnt,
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struct rpc_xprt_switch *xps,
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struct rpc_xprt *xprt,
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void *dummy);
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int rpc_clnt_add_xprt(struct rpc_clnt *, struct xprt_create *,
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int (*setup)(struct rpc_clnt *,
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struct rpc_xprt_switch *,
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struct rpc_xprt *,
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void *),
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void *data);
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void rpc_set_connect_timeout(struct rpc_clnt *clnt,
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unsigned long connect_timeout,
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unsigned long reconnect_timeout);
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int rpc_clnt_setup_test_and_add_xprt(struct rpc_clnt *,
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struct rpc_xprt_switch *,
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struct rpc_xprt *,
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void *);
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const char *rpc_proc_name(const struct rpc_task *task);
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void rpc_clnt_xprt_switch_put(struct rpc_clnt *);
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void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *, struct rpc_xprt *);
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bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
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const struct sockaddr *sap);
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void rpc_cleanup_clids(void);
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static inline int rpc_reply_expected(struct rpc_task *task)
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{
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return (task->tk_msg.rpc_proc != NULL) &&
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(task->tk_msg.rpc_proc->p_decode != NULL);
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}
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#endif /* _LINUX_SUNRPC_CLNT_H */
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