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![Linus Torvalds](/assets/img/avatar_default.png)
The poll() changes were not well thought out, and completely unexplained. They also caused a huge performance regression, because "->poll()" was no longer a trivial file operation that just called down to the underlying file operations, but instead did at least two indirect calls. Indirect calls are sadly slow now with the Spectre mitigation, but the performance problem could at least be largely mitigated by changing the "->get_poll_head()" operation to just have a per-file-descriptor pointer to the poll head instead. That gets rid of one of the new indirections. But that doesn't fix the new complexity that is completely unwarranted for the regular case. The (undocumented) reason for the poll() changes was some alleged AIO poll race fixing, but we don't make the common case slower and more complex for some uncommon special case, so this all really needs way more explanations and most likely a fundamental redesign. [ This revert is a revert of about 30 different commits, not reverted individually because that would just be unnecessarily messy - Linus ] Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
256 lines
7 KiB
C
256 lines
7 KiB
C
/*
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* if_alg: User-space algorithm interface
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*
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* Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#ifndef _CRYPTO_IF_ALG_H
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#define _CRYPTO_IF_ALG_H
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#include <linux/compiler.h>
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#include <linux/completion.h>
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#include <linux/if_alg.h>
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#include <linux/scatterlist.h>
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#include <linux/types.h>
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#include <linux/atomic.h>
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#include <net/sock.h>
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#include <crypto/aead.h>
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#include <crypto/skcipher.h>
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#define ALG_MAX_PAGES 16
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struct crypto_async_request;
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struct alg_sock {
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/* struct sock must be the first member of struct alg_sock */
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struct sock sk;
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struct sock *parent;
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unsigned int refcnt;
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unsigned int nokey_refcnt;
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const struct af_alg_type *type;
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void *private;
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};
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struct af_alg_control {
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struct af_alg_iv *iv;
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int op;
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unsigned int aead_assoclen;
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};
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struct af_alg_type {
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void *(*bind)(const char *name, u32 type, u32 mask);
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void (*release)(void *private);
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int (*setkey)(void *private, const u8 *key, unsigned int keylen);
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int (*accept)(void *private, struct sock *sk);
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int (*accept_nokey)(void *private, struct sock *sk);
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int (*setauthsize)(void *private, unsigned int authsize);
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struct proto_ops *ops;
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struct proto_ops *ops_nokey;
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struct module *owner;
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char name[14];
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};
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struct af_alg_sgl {
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struct scatterlist sg[ALG_MAX_PAGES + 1];
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struct page *pages[ALG_MAX_PAGES];
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unsigned int npages;
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};
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/* TX SGL entry */
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struct af_alg_tsgl {
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struct list_head list;
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unsigned int cur; /* Last processed SG entry */
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struct scatterlist sg[0]; /* Array of SGs forming the SGL */
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};
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#define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \
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sizeof(struct scatterlist) - 1)
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/* RX SGL entry */
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struct af_alg_rsgl {
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struct af_alg_sgl sgl;
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struct list_head list;
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size_t sg_num_bytes; /* Bytes of data in that SGL */
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};
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/**
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* struct af_alg_async_req - definition of crypto request
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* @iocb: IOCB for AIO operations
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* @sk: Socket the request is associated with
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* @first_rsgl: First RX SG
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* @last_rsgl: Pointer to last RX SG
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* @rsgl_list: Track RX SGs
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* @tsgl: Private, per request TX SGL of buffers to process
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* @tsgl_entries: Number of entries in priv. TX SGL
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* @outlen: Number of output bytes generated by crypto op
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* @areqlen: Length of this data structure
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* @cra_u: Cipher request
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*/
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struct af_alg_async_req {
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struct kiocb *iocb;
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struct sock *sk;
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struct af_alg_rsgl first_rsgl;
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struct af_alg_rsgl *last_rsgl;
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struct list_head rsgl_list;
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struct scatterlist *tsgl;
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unsigned int tsgl_entries;
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unsigned int outlen;
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unsigned int areqlen;
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union {
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struct aead_request aead_req;
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struct skcipher_request skcipher_req;
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} cra_u;
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/* req ctx trails this struct */
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};
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/**
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* struct af_alg_ctx - definition of the crypto context
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*
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* The crypto context tracks the input data during the lifetime of an AF_ALG
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* socket.
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*
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* @tsgl_list: Link to TX SGL
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* @iv: IV for cipher operation
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* @aead_assoclen: Length of AAD for AEAD cipher operations
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* @completion: Work queue for synchronous operation
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* @used: TX bytes sent to kernel. This variable is used to
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* ensure that user space cannot cause the kernel
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* to allocate too much memory in sendmsg operation.
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* @rcvused: Total RX bytes to be filled by kernel. This variable
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* is used to ensure user space cannot cause the kernel
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* to allocate too much memory in a recvmsg operation.
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* @more: More data to be expected from user space?
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* @merge: Shall new data from user space be merged into existing
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* SG?
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* @enc: Cryptographic operation to be performed when
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* recvmsg is invoked.
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* @len: Length of memory allocated for this data structure.
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*/
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struct af_alg_ctx {
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struct list_head tsgl_list;
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void *iv;
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size_t aead_assoclen;
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struct crypto_wait wait;
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size_t used;
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atomic_t rcvused;
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bool more;
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bool merge;
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bool enc;
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unsigned int len;
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};
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int af_alg_register_type(const struct af_alg_type *type);
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int af_alg_unregister_type(const struct af_alg_type *type);
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int af_alg_release(struct socket *sock);
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void af_alg_release_parent(struct sock *sk);
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int af_alg_accept(struct sock *sk, struct socket *newsock, bool kern);
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int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len);
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void af_alg_free_sg(struct af_alg_sgl *sgl);
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void af_alg_link_sg(struct af_alg_sgl *sgl_prev, struct af_alg_sgl *sgl_new);
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int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con);
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static inline struct alg_sock *alg_sk(struct sock *sk)
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{
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return (struct alg_sock *)sk;
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}
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/**
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* Size of available buffer for sending data from user space to kernel.
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*
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* @sk socket of connection to user space
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* @return number of bytes still available
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*/
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static inline int af_alg_sndbuf(struct sock *sk)
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{
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struct alg_sock *ask = alg_sk(sk);
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struct af_alg_ctx *ctx = ask->private;
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return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
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ctx->used, 0);
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}
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/**
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* Can the send buffer still be written to?
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*
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* @sk socket of connection to user space
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* @return true => writable, false => not writable
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*/
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static inline bool af_alg_writable(struct sock *sk)
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{
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return PAGE_SIZE <= af_alg_sndbuf(sk);
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}
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/**
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* Size of available buffer used by kernel for the RX user space operation.
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*
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* @sk socket of connection to user space
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* @return number of bytes still available
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*/
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static inline int af_alg_rcvbuf(struct sock *sk)
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{
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struct alg_sock *ask = alg_sk(sk);
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struct af_alg_ctx *ctx = ask->private;
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return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) -
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atomic_read(&ctx->rcvused), 0);
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}
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/**
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* Can the RX buffer still be written to?
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*
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* @sk socket of connection to user space
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* @return true => writable, false => not writable
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*/
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static inline bool af_alg_readable(struct sock *sk)
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{
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return PAGE_SIZE <= af_alg_rcvbuf(sk);
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}
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int af_alg_alloc_tsgl(struct sock *sk);
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unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes, size_t offset);
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void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
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size_t dst_offset);
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void af_alg_free_areq_sgls(struct af_alg_async_req *areq);
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int af_alg_wait_for_wmem(struct sock *sk, unsigned int flags);
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void af_alg_wmem_wakeup(struct sock *sk);
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int af_alg_wait_for_data(struct sock *sk, unsigned flags);
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void af_alg_data_wakeup(struct sock *sk);
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int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
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unsigned int ivsize);
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ssize_t af_alg_sendpage(struct socket *sock, struct page *page,
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int offset, size_t size, int flags);
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void af_alg_free_resources(struct af_alg_async_req *areq);
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void af_alg_async_cb(struct crypto_async_request *_req, int err);
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__poll_t af_alg_poll(struct file *file, struct socket *sock,
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poll_table *wait);
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struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk,
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unsigned int areqlen);
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int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
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struct af_alg_async_req *areq, size_t maxsize,
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size_t *outlen);
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#endif /* _CRYPTO_IF_ALG_H */
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