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Revision bce0b6c51ac76fc0e763262a6c2a9d05e486f0d8 authored by Steven Rostedt (Red Hat) on 21 August 2014, 03:57:04 UTC, committed by Steven Rostedt on 22 August 2014, 19:24:12 UTC 
ftrace: Fix up trampoline accounting with looping on hash ops
 
Now that a ftrace_hash can be shared by multiple ftrace_ops, they can dec
the rec->flags by more than once (one per those that share the ftrace_hash).
This means that the tramp_hash may not have a hash item when it was added.

For example, if two ftrace_ops share a hash for a ftrace record, and the
first ops has a trampoline, when it adds itself it will set the rec->flags
TRAMP flag and increments its nr_trampolines counter. When the second ops
is added, it must clear that tramp flag but also decrement the other ops
that shares its hash. As the update to the function callbacks has not yet
been performed, the other ops will not have the tramp hash set yet and it
can not be used to know to decrement its nr_trampolines.

Luckily, the tramp_hash does not need to be used. As the ftrace_mutex is
held, a ops with a trampoline to a record during an update of another ops
that shares the record will have its func_hash pointing to it. Since a
trampoline can only be set for a record if only one ops is attached to it,
we can just check if the record has a trampoline (the FTRACE_FL_TRAMP flag
is set) and then find the ops that has this record in its hashes.

Also added some output to help debug when things go wrong.

Cc: stable@vger.kernel.org # 3.16+ (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 parent 8426191
Raw File
if_alg.h 
/*
 * if_alg: User-space algorithm interface
 *
 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#ifndef _CRYPTO_IF_ALG_H
#define _CRYPTO_IF_ALG_H

#include <linux/compiler.h>
#include <linux/completion.h>
#include <linux/if_alg.h>
#include <linux/scatterlist.h>
#include <linux/types.h>
#include <net/sock.h>

#define ALG_MAX_PAGES			16

struct crypto_async_request;

struct alg_sock {
	/* struct sock must be the first member of struct alg_sock */
	struct sock sk;

	struct sock *parent;

	const struct af_alg_type *type;
	void *private;
};

struct af_alg_completion {
	struct completion completion;
	int err;
};

struct af_alg_control {
	struct af_alg_iv *iv;
	int op;
};

struct af_alg_type {
	void *(*bind)(const char *name, u32 type, u32 mask);
	void (*release)(void *private);
	int (*setkey)(void *private, const u8 *key, unsigned int keylen);
	int (*accept)(void *private, struct sock *sk);

	struct proto_ops *ops;
	struct module *owner;
	char name[14];
};

struct af_alg_sgl {
	struct scatterlist sg[ALG_MAX_PAGES];
	struct page *pages[ALG_MAX_PAGES];
};

int af_alg_register_type(const struct af_alg_type *type);
int af_alg_unregister_type(const struct af_alg_type *type);

int af_alg_release(struct socket *sock);
int af_alg_accept(struct sock *sk, struct socket *newsock);

int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
		   int write);
void af_alg_free_sg(struct af_alg_sgl *sgl);

int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con);

int af_alg_wait_for_completion(int err, struct af_alg_completion *completion);
void af_alg_complete(struct crypto_async_request *req, int err);

static inline struct alg_sock *alg_sk(struct sock *sk)
{
	return (struct alg_sock *)sk;
}

static inline void af_alg_release_parent(struct sock *sk)
{
	sock_put(alg_sk(sk)->parent);
}

static inline void af_alg_init_completion(struct af_alg_completion *completion)
{
	init_completion(&completion->completion);
}

#endif	/* _CRYPTO_IF_ALG_H */
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