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341f741f04
A static checker warning occurs in the AFS filesystem:
fs/afs/cmservice.c:155 SRXAFSCB_CallBack()
error: dereferencing freed memory 'call'
due to the reply being sent before we access the server it points to. The
act of sending the reply causes the call to be freed if an error occurs
(but not if it doesn't).
On top of this, the lifetime handling of afs_call structs is fragile
because they get passed around through workqueues without any sort of
refcounting.
Deal with the issues by:
(1) Fix the maybe/maybe not nature of the reply sending functions with
regards to whether they release the call struct.
(2) Refcount the afs_call struct and sort out places that need to get/put
references.
(3) Pass a ref through the work queue and release (or pass on) that ref in
the work function. Care has to be taken because a work queue may
already own a ref to the call.
(4) Do the cleaning up in the put function only.
(5) Simplify module cleanup by always incrementing afs_outstanding_calls
whenever a call is allocated.
(6) Set the backlog to 0 with kernel_listen() at the beginning of the
process of closing the socket to prevent new incoming calls from
occurring and to remove the contribution of preallocated calls from
afs_outstanding_calls before we wait on it.
A tracepoint is also added to monitor the afs_call refcount and lifetime.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Fixes: 08e0e7c82e: "[AF_RXRPC]: Make the in-kernel AFS filesystem use AF_RXRPC."
185 lines
4.6 KiB
C
185 lines
4.6 KiB
C
/* AFS tracepoints
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*
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* Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#undef TRACE_SYSTEM
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#define TRACE_SYSTEM afs
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#if !defined(_TRACE_AFS_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_AFS_H
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#include <linux/tracepoint.h>
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/*
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* Define enums for tracing information.
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*/
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#ifndef __AFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
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#define __AFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
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enum afs_call_trace {
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afs_call_trace_alloc,
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afs_call_trace_free,
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afs_call_trace_put,
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afs_call_trace_wake,
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afs_call_trace_work,
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};
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#endif /* end __AFS_DECLARE_TRACE_ENUMS_ONCE_ONLY */
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/*
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* Declare tracing information enums and their string mappings for display.
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*/
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#define afs_call_traces \
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EM(afs_call_trace_alloc, "ALLOC") \
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EM(afs_call_trace_free, "FREE ") \
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EM(afs_call_trace_put, "PUT ") \
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EM(afs_call_trace_wake, "WAKE ") \
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E_(afs_call_trace_work, "WORK ")
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/*
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* Export enum symbols via userspace.
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*/
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#undef EM
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#undef E_
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#define EM(a, b) TRACE_DEFINE_ENUM(a);
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#define E_(a, b) TRACE_DEFINE_ENUM(a);
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afs_call_traces;
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/*
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* Now redefine the EM() and E_() macros to map the enums to the strings that
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* will be printed in the output.
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*/
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#undef EM
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#undef E_
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#define EM(a, b) { a, b },
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#define E_(a, b) { a, b }
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TRACE_EVENT(afs_recv_data,
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TP_PROTO(struct afs_call *call, unsigned count, unsigned offset,
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bool want_more, int ret),
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TP_ARGS(call, count, offset, want_more, ret),
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TP_STRUCT__entry(
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__field(struct rxrpc_call *, rxcall )
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__field(struct afs_call *, call )
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__field(enum afs_call_state, state )
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__field(unsigned int, count )
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__field(unsigned int, offset )
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__field(unsigned short, unmarshall )
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__field(bool, want_more )
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__field(int, ret )
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),
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TP_fast_assign(
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__entry->rxcall = call->rxcall;
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__entry->call = call;
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__entry->state = call->state;
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__entry->unmarshall = call->unmarshall;
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__entry->count = count;
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__entry->offset = offset;
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__entry->want_more = want_more;
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__entry->ret = ret;
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),
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TP_printk("c=%p ac=%p s=%u u=%u %u/%u wm=%u ret=%d",
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__entry->rxcall,
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__entry->call,
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__entry->state, __entry->unmarshall,
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__entry->offset, __entry->count,
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__entry->want_more, __entry->ret)
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);
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TRACE_EVENT(afs_notify_call,
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TP_PROTO(struct rxrpc_call *rxcall, struct afs_call *call),
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TP_ARGS(rxcall, call),
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TP_STRUCT__entry(
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__field(struct rxrpc_call *, rxcall )
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__field(struct afs_call *, call )
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__field(enum afs_call_state, state )
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__field(unsigned short, unmarshall )
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),
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TP_fast_assign(
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__entry->rxcall = rxcall;
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__entry->call = call;
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__entry->state = call->state;
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__entry->unmarshall = call->unmarshall;
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),
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TP_printk("c=%p ac=%p s=%u u=%u",
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__entry->rxcall,
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__entry->call,
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__entry->state, __entry->unmarshall)
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);
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TRACE_EVENT(afs_cb_call,
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TP_PROTO(struct afs_call *call),
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TP_ARGS(call),
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TP_STRUCT__entry(
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__field(struct rxrpc_call *, rxcall )
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__field(struct afs_call *, call )
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__field(const char *, name )
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__field(u32, op )
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),
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TP_fast_assign(
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__entry->rxcall = call->rxcall;
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__entry->call = call;
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__entry->name = call->type->name;
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__entry->op = call->operation_ID;
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),
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TP_printk("c=%p ac=%p %s o=%u",
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__entry->rxcall,
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__entry->call,
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__entry->name,
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__entry->op)
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);
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TRACE_EVENT(afs_call,
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TP_PROTO(struct afs_call *call, enum afs_call_trace op,
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int usage, int outstanding, const void *where),
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TP_ARGS(call, op, usage, outstanding, where),
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TP_STRUCT__entry(
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__field(struct afs_call *, call )
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__field(int, op )
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__field(int, usage )
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__field(int, outstanding )
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__field(const void *, where )
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),
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TP_fast_assign(
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__entry->call = call;
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__entry->op = op;
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__entry->usage = usage;
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__entry->outstanding = outstanding;
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__entry->where = where;
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),
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TP_printk("c=%p %s u=%d o=%d sp=%pSR",
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__entry->call,
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__print_symbolic(__entry->op, afs_call_traces),
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__entry->usage,
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__entry->outstanding,
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__entry->where)
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);
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#endif /* _TRACE_AFS_H */
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/* This part must be outside protection */
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#include <trace/define_trace.h>
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